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Cisco IOS XR Routing Command Reference, Release 3.2
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Preface
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BGP Commands on Cisco IOS XR Software
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IS-IS Commands on Cisco IOS XR Software
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OSPF Commands on Cisco IOS XR Software
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OSPFv3 Commands on Cisco IOS XR Software
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RIB Commands on Cisco IOS XR Software
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Routing Policy Language Commands on Cisco IOS XR Software
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Static and Utility Routing Commands on Cisco IOS XR Software
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Index
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Table Of Contents
BGP Commands on Cisco IOS XR Software
bgp auto-policy-soft-reset disable
bgp bestpath med missing-as-worst
bgp client-to-client reflection disable
bgp fast-external-fallover disable
bgp graceful-restart graceful-reset
bgp graceful-restart purge-time
bgp graceful-restart restart-time
bgp graceful-restart stalepath-time
bgp log neighbor changes disable
clear bgp performance-statistics
default-information originate (BGP)
show bgp truncated-communities
BGP Commands on Cisco IOS XR Software
This chapter describes the commands used to configure and monitor Border Gateway Protocol (BGP) for IP Version 4 (IPv4) and IP Version 6 (IPv6) routing sessions.
For detailed information about BGP concepts, configuration tasks, and examples, see the Implementing BGP on Cisco IOS XR Software configuration guide.
address-family (BGP)
To enter various address family configuration modes while configuring Border Gateway Protocol (BGP), use the address-family command in an appropriate configuration mode. To disable support for an address family, use the no form of this command.
address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast}
no address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast}
Syntax Description
Defaults
An address family must be explicitly configured in the router configuration mode for the address family to be active in BGP. Similarly, an address family must be configured under the neighbor for the BGP session to be established for that address family. An address family must be configured in router configuration mode before it can be configured under a neighbor.
Command Modes
Router configuration
Neighbor configuration
Neighbor group configurationCommand History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the address-family command to enter various address family configuration modes while configuring BGP routing sessions. When you enter the address-family command from router configuration mode, you enable the address family and enter global address family configuration mode.
When you enter the address-family command from neighbor configuration mode, you activate the address family on the neighbor and enter neighbor address family configuration mode.
For IPv4 neighbors, the default address family is IPv4 unicast.
Note
It is not necessary to have an address family configured in router configuration mode for either an IPv4 or IPv6 neighbor to be configured. However, to be able to configure an address family under a neighbor, the same address family must be configured in router configuration mode. It is not possible to bring up a session for a neighbor under a specific address family unless the address family is configured for the neighbor.
Examples
The following example shows how to place the router in global address family configuration mode for the IPv4 address family:
RP/0/RP0/CPU0:router# configureRP/0/RP0/CPU0:router(config)# router bgp 100RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)#The following example shows how to activate IPv4 multicast for neighbor 10.0.0.1 and place the router in neighbor address family configuration mode for the IPv4 multicast address family:
RP/0/RP0/CPU0:router# configureRP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.0.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 multicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)#advertisement-interval
To set the minimum interval between the sending of Border Gateway Protocol (BGP) routing updates, use the advertisement-interval command in the appropriate configuration mode. To remove the advertisement-interval command from the configuration file and restore the system to its default interval values, use the no form of this command.
advertisement-interval seconds
no advertisement-interval
Syntax Description
Defaults
30 seconds for external peers and 5 seconds for internal peers.
Command Modes
Neighbor configuration
Neighbor group configuration
Session group configurationCommand History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
If this command configures a neighbor group or session group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Examples
The following example shows how to set the minimum time between sending BGP routing updates to 10 seconds:
RP/0/RP0/CPU0:router(config)# router bgp 5RP/0/RP0/CPU0:router(config-bgp)# neighbor 10.1.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 100RP/0/RP0/CPU0:router(config-bgp-nbr)# advertisement-interval 10Related Commands
Creates a neighbor group and enters neighbor group configuration mode.
Creates a session group and enters session group configuration mode.
af-group
To create an address family group for Border Gateway Protocol (BGP) neighbors and enter address family group configuration mode, use the af-group command in router configuration mode. To remove an address family group, use the no form of this command.
af-group af-group-name address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast}
no af-group af-group-name address-family {ipv4 unicast | ipv4 multicast | ipv6 unicast | ipv6 multicast}
Syntax Description
Defaults
No BGP address family group is configured.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the af-group command to group address family-specific neighbor commands within an IPv4 or IPv6 address family. Neighbors that have address family configuration are able to use the address family group. Further, neighbors inherit the configuration parameters of the entire address family group. This feature replaces part of the functionality of peer groups found in previous Cisco IOS XR software releases.
You cannot define two address family groups with the same name in different address families.
Examples
The following example shows how to create address family group group1 and enter address family group configuration mode for IPv4 unicast. Group1 contains the next-hop-self feature, which is inherited by neighbors that want to use address family group1.
RP/0/RP0/CPU0:router(config)# router bgp 100RP/0/RP0/CPU0:router(config-bgp)# af-group group1 address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-afgrp)# next-hop-selfRelated Commands
aggregate-address
To create an aggregate entry in a Border Gateway Protocol (BGP) routing table, use the aggregate-address command in global address family configuration mode. To remove the aggregate-address command from the configuration file and restore the system to its default condition, use the no form of this command.
aggregate-address address/mask-length [as-set] [as-confed-set] [summary-only] [route-policy route-policy-name]
no aggregate-address address/mask-length
Syntax Description
Defaults
When you do not specify this command, no aggregate entry is created in the BGP routing table.
Command Modes
Address family configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
You can implement aggregate routing in BGP either by redistributing an aggregate route into BGP using the network command or the aggregate-address command.
Use the aggregate-address command without optional arguments to create an aggregate entry in the BGP routing table if any more-specific BGP routes are available that fall in the specified range. The aggregate route is advertised as coming from your autonomous system and has the atomic aggregate attribute set to show that information might be missing. (By default, the atomic aggregate attribute is set unless you specify the as-set keyword.)
Use of the as-set keyword creates an aggregate entry using the same rules that the command follows without this keyword. However, the advertised path for this route is an AS_SET, a set of all autonomous systems contained in all paths that are being summarized.
Do not use this form of the aggregate-address command when aggregating many paths because this route must be continually withdrawn and updated as autonomous system path reachability information for the summarized routes changes.
Use the as-confed-set keyword to create an AS_CONFED_SET in the autonomous system path of the aggregate from any confederation segments in the paths being summarized. This keyword takes effect only if the as-set keyword is also specified.
Use of the summary-only keyword creates an aggregate entry (for example, 10.0.0.0/8) but suppresses advertisements of more-specific routes to all neighbors. If you want to suppress only advertisements to certain neighbors, use the route-policy (BGP) command in neighbor address family configuration mode with caution. If a more-specific route leaks out, all BGP speakers (the local router) prefer that route over the less-specific aggregate you generate (using longest-match routing).
Use the route-policy keyword to specify a routing policy for the aggregate entry. The route-policy keyword is used to select which more-specific information to base the aggregate entry on and which more-specific information to suppress. You can also use the keyword to modify the attributes of the aggregate entry.
Examples
The following example shows how to create an aggregate address. The path advertised for this route is an autonomous system set consisting of all elements contained in all paths that are being summarized.
RP/0/RP0/CPU0:router(config)# router bgp 100RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# aggregate-address 10.0.0.0/8 as-setRelated Commands
bgp as-path-loopcheck
To enable an autonomous system path for loop checking internal Border Gateway Protocol (iBGP) peers, use the bgp as-path-loopcheck command in router configuration mode. To restore the system to its default condition, use the no form of this command.
bgp as-path-loopcheck
no bgp as-path-loopcheck
Syntax Description
This command has no arguments or keywords.
Defaults
When you do not specify this command, loop checking is performed only for external peers.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Examples
The following example shows how to configure an autonomous system path for loop checking iBGP peers:
RP/0/RP0/CPU0:router(config)# router bgp 6RP/0/RP0/CPU0:router(config-bgp)# bgp as-path-loopcheckbgp attribute-download
To enable Border Gateway Protocol (BGP) attribute download, use the bgp attribute-download command in address family configuration mode. To disable BGP attribute download, use the no form of this command.
bgp attribute-download
no bgp attribute-download
Syntax Description
This command has no arguments or keywords.
Defaults
BGP attribute download is not enabled.
Command Modes
Address family configuration
Command History
Release 3.2
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
When BGP attribute download is enabled using the bgp attribute-download command, BGP reinstalls all routes whose attributes are not currently in the RIB. Likewise, if the user disables BGP attribute download using the no form of the command, BGP reinstalls previously installed routes with a null key, and removes the attributes from the RIB.
Examples
The following example shows how to enable BGP attribute download on BGP router 50:
RP/0/RP0/CPU0:router(config)# router bgp 50RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# bgp attribute-downloadbgp auto-policy-soft-reset disable
To disable an automatic reset of Border Gateway Protocol (BGP) peers when their configured route policy is modified, use the bgp auto-policy-soft-reset disable command in router configuration mode. To re-enable automatic soft reset of BGP peers, use the no form of this command.
bgp auto-policy-soft-reset disable
no bgp auto-policy-soft-reset disable
Syntax Description
This command has no arguments or keywords.
Defaults
Automatic soft reset of peers is enabled.
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Note
Examples
The following example shows how to disable an automatic soft reset of BGP peers when their configured route policy is modified:
RP/0/RP0/CPU0:router(config)# router bgp 6RP/0/RP0/CPU0:router(config-bgp)# bgp auto-policy-soft-reset disable
bgp bestpath as-path ignore
To ignore the autonomous system path length when calculating preferred paths, use the bgp bestpath as-path ignore command in router configuration mode. To return the software to the default state in which it considers the autonomous system path length when calculating preferred paths, use the no form of this command.
bgp bestpath as-path ignore
no bgp bestpath as-path ignore
Syntax Description
This command has no arguments or keywords.
Defaults
The autonomous system path length is used (not ignored) when a best path is selected.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the bgp bestpath as-path ignore command to ignore the length of autonomous system paths when the software selects a preferred path. When the best path is selected, if this command is specified, all steps are performed as usual except comparison of the autonomous path length between candidate paths.
Examples
The following example shows how to configure the software to ignore the autonomous system length when performing best path selection:
RP/0/RP0/CPU0:router(config)# router bgp 65000RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath as-path ignoreRelated Commands
bgp bestpath compare-routerid
To compare identical routes received from external BGP (eBGP) peers during the best path selection process and select the route with the lowest router ID, use the bgp bestpath compare-routerid command in router configuration mode. To disable comparing identical routes received from eBGP peers during best path selection, use the no form of this command.
bgp bestpath compare-routerid
no bgp bestpath compare-routerid
Syntax Description
This command has no arguments or keywords.
Defaults
The software does not select a new best path if it is the same as the current best path (according to the BGP selection algorithm) except for the router ID.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the bgp bestpath compare-routerid command to affect how the software selects the best path, in the case where there are two paths of equal cost according to the BGP selection algorithm. This command is used to force the software to select the path with the lower router ID as the best path. If this command is not used, the software continues to use whichever path is currently the best path, regardless of which has the lower router ID.
Examples
The following example shows how to configure the BGP speaker in autonomous system 500 to compare the router IDs of similar paths:
RP/0/RP0/CPU0:router(config)# router bgp 500RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath compare-routeridRelated Commands
bgp bestpath med always
To allow the comparison of the Multi Exit Discriminator (MED) for paths from neighbors in different autonomous systems, use the bgp bestpath med always command in router configuration mode. To disable considering the MED attribute in comparing paths, use the no form of this command.
bgp bestpath med always
no bgp bestpath med always
Syntax Description
This command has no arguments or keywords.
Defaults
The software does not compare MEDs for paths between neighbors in different autonomous systems.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
The MED is one of the parameters that is considered by the software when selecting the best path among many alternative paths. The software chooses the path with the lowest MED.
By default, during the best path selection process, the software makes a MED comparison only among paths from the same autonomous system. This command changes the default behavior of the software by allowing comparison of MEDs, among paths regardless of the autonomous system from which the paths are received.
Examples
The following example shows how to configure the Border Gateway Protocol (BGP) speaker in autonomous system 100 to compare MEDs among alternative paths, regardless of the autonomous system from which the paths are received:
RP/0/RP0/CPU0:router(config)# router bgp 100RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath med alwaysRelated Commands
bgp bestpath med confed
To enable Multi Exit Discriminator (MED) comparison among paths learned from confederation peers, use the bgp bestpath med confed command in router configuration mode. To disable the software from considering the MED attribute in comparing paths, use the no form of this command.
bgp bestpath med confed
no bgp bestpath med confed
Syntax Description
This command has no arguments or keywords.
Defaults
The software does not compare the MED of paths containing only confederation segments, or paths containing confederation segments followed by an AS_SET, with the MED of any other paths.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
By default, the MED of the following paths is not compared with the MED of any other path:
•
•
•
•
Use the bgp bestpath med confed command to affect how the following types of paths are treated in the BGP best path algorithm:
•
•
The MED for paths that start with an AS_SEQUENCE or that start with confederation segments followed by an AS_SEQUENCE only is compared with the MED of other paths that share the same first autonomous system number in the autonomous system sequence (the neighbor autonomous system number). This behavior is not affected by the bgp bestpath med confed command.
As an example, suppose that autonomous systems 65000, 65001, 65002, and 65004 are part of a confederation, but autonomous system 1 is not. Suppose that for a particular route, the following paths exist:
•
•
•
If the bgp bestpath med confed command is enabled, the software selects path 1 as the best path because it:
•
•
The MED is not compared with path 3 because it has an external autonomous system number (that is, an AS_SEQUENCE) in the path. If the bgp bestpath med confed command is not enabled, then MED is not compared between any of these paths. Consequently, the software selects path 2 as the best path because it has the lowest IGP metric.
Examples
The following command shows how to enable Border Gateway Protocol (BGP) software to compare MED values for paths learned from confederation peers:
RP/0/RP0/CPU0:router(config)# router bgp 210RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath med confedRelated Commands
bgp bestpath med missing-as-worst
To have the software consider a missing Multi Exit Discriminator (MED) attribute in a path as having a value of infinity, making the path without a MED value the least desirable path, use the bgp bestpath med missing-as-worst command in router configuration mode. To disable considering the MED attribute in comparing paths, use the no form of this command.
bgp bestpath med missing-as-worst
no bgp bestpath med missing-as-worst
Syntax Description
This command has no arguments or keywords.
Defaults
The software assigns a value of 0 to the missing MED, causing the path with the missing MED attribute to be considered as the best possible MED.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Examples
The following example shows how to direct the Border Gateway Protocol (BGP) software to consider a missing MED attribute in a path as having a value of infinity, making this path the least desirable path:
RP/0/RP0/CPU0:router(config)# router bgp 210RP/0/RP0/CPU0:router(config-bgp)# bgp bestpath med missing-as-worstRelated Commands
bgp client-to-client reflection disable
To disable reflection of routes between route-reflection clients using a Border Gateway Protocol (BGP) route reflector, use the bgp client-to-client reflection disable command in address family configuration mode. To re-enable client-to-client reflection, use the no form of this command.
bgp client-to-client reflection disable
no bgp client-to-client reflection disable
Syntax Description
This command has no arguments or keywords.
Defaults
Client-to-client reflection is enabled.
Command Modes
Address family configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
By default, the clients of a route reflector are not required to be fully meshed and the routes from a client are reflected to other clients. However, if the clients are fully meshed, route reflection is not required.
Examples
In this example, the three neighbors are fully meshed, so client-to-client reflection is disabled:
RP/0/RP0/CPU0:router(config)# router bgp 65534RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# bgp client-to-client reflection disableRP/0/RP0/CPU0:router(config-bgp-af)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor-group rrclientsRP/0/RP0/CPU0:router(config-bgp-nbrgrp)# remote-as 65534RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# route-reflector-clientRP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# exitRP/0/RP0/CPU0:router(config-bgp-nbrgrp)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.253.21 use neighbor-group rrclientsRP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.253.22 use neighbor-group rrclientsRelated Commands
bgp cluster-id
To configure the cluster ID if the Border Gateway Protocol (BGP) cluster has more than one route reflector, use the bgp cluster-id command in router configuration mode. To remove the cluster ID, use the no form of this command.
bgp cluster-id cluster-id
no bgp cluster-id
Syntax Description
cluster-id
Cluster ID of this router acting as a route reflector; maximum of 4 bytes. Cluster ID can be entered either as an IP address or value. Range is 1 to 429496729.
Defaults
A cluster ID is not configured.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Together, a route reflector and its clients form a cluster. A cluster of clients usually has a single route reflector. In such instances, the cluster is identified by the software as the router ID of the route reflector. To increase redundancy and avoid a single point of failure in the network, a cluster might have more than one route reflector. If it does, all route reflectors in the cluster must be configured with the same 4-byte cluster ID so that a route reflector can recognize updates from route reflectors in the same cluster.
If the cluster has more than one route reflector, use the bgp cluster-id command to configure the cluster ID.
Examples
The following example shows how to configure the local router as one of the route reflectors serving the cluster. It is configured with the cluster ID to identify the cluster.
RP/0/RP0/CPU0:router(config)# router bgp 65534RP/0/RP0/CPU0:router(config-bgp)# bgp cluster-id 192.168.70.1RP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.70.24RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 65534RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# route-reflector-clientRelated Commands
bgp confederation identifier
To specify a Border Gateway Protocol (BGP) confederation identifier, use the bgp confederation identifier command in router configuration mode. To remove the confederation identifier, use the no form of this command.
bgp confederation identifier autonomous-system-number
no bgp confederation identifier
Syntax Description
autonomous-system-number
Autonomous system number that internally includes multiple autonomous systems.
Defaults
No confederation identifier is configured.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
One way to reduce the internal BGP (iBGP) mesh is to divide an autonomous system into multiple autonomous systems and group them into a single confederation. Each autonomous system is fully meshed within itself, and has a few connections to another autonomous system in the same confederation. Although the peers in different autonomous systems have external BGP (eBGP) sessions, they exchange routing information as if they are iBGP peers. Specifically, the confederation maintains the next hop and local preference information, and that allows you to retain a single Interior Gateway Protocol (IGP) for all autonomous systems. To the outside world, the confederation looks like a single autonomous system.
Use the bgp confederation identifier command to specify the autonomous system number for the confederation. This autonomous system number is used when BGP sessions are established with external peers in autonomous systems that are not part of the confederation.
Examples
The following example shows how to divide the autonomous system into autonomous systems 4001, 4002, 4003, 4004, 4005, 4006, and 4007 with the confederation identifier 5. Neighbor 10.2.3.4 is a router inside the confederation. Neighbor 172.20.16.6 is outside the routing domain confederation. To the outside world, there appears to be a single autonomous system with the number 5.
RP/0/RP0/CPU0:router(config)# router bgp 4001RP/0/RP0/CPU0:router(config-bgp)# bgp confederation identifier 5RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 4002RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 4003RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 4004RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 4005RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 4006RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 4007RP/0/RP0/CPU0:router(config-bgp)# neighbor 10.2.3.4RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 4002RP/0/RP0/CPU0:router(config-bgp-nbr)# exitRP/0/RP0/CPU0:router(config-bgp)# exitRP/0/RP0/CPU0:router(config-bgp-nbr)# neighbor 172.20.16.6RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 4009Related Commands
bgp confederation peers
To configure the autonomous systems that belong to the confederation, use the bgp confederation peers command in router configuration mode. To remove the autonomous system from the confederation, use the no form of this command.
bgp confederation peers autonomous-system-number
no bgp confederation peers autonomous-system-number
Syntax Description
autonomous-system-number
Autonomous system numbers for Border Gateway Protocol (BGP) peers that belong to the confederation. Enter one autonomous system number for each command line.
Defaults
No BGP peers are identified as belonging to the confederation.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
The autonomous systems specified in this command are visible internally to a confederation. Each autonomous system is fully meshed within itself. The bgp confederation identifier command specifies the confederation to which the autonomous systems belong.
Examples
The following example shows that autonomous systems 1090, 1091, 1092, and 1093 belong to a single confederation:
RP/0/RP0/CPU0:router(config)# router bgp 1090RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 1091RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 1092RP/0/RP0/CPU0:router(config-bgp)# bgp confederation peers 1093Related Commands
bgp dampening
To enable Border Gateway Protocol (BGP) route dampening or change various BGP route dampening factors, use the bgp dampening command in address family configuration mode. To disable route dampening and reset default values, use the no form of this command.
bgp dampening [half-life [reuse suppress max-suppress-time] | route-policy route-policy-name]
no bgp dampening
Syntax Description
Defaults
Route dampening is disabled.
half-life: 15 minutes
reuse: 750
suppress: 2000
max-suppress-time: four times half-life valueCommand Modes
Address family configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the bgp dampening command without arguments to enable BGP route dampening with the default parameters. The parameters can be changed by setting them on the command line or specifying them with a routing policy.
Examples
The following example shows how to set the half-life value to 30 minutes, the reuse value to 1500, the suppress value to 10000, and the max-suppress-time to 120 minutes:
RP/0/RP0/CPU0:router(config)# router bgp 50RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# bgp dampening 30 1500 10000 120Related Commands
bgp default local-preference
To change the default local preference value, use the bgp default local-preference command in router configuration mode. To reset the local preference value to the default of 100, use the no form of this command.
bgp default local-preference value
no bgp default local-preference
Syntax Description
Defaults
Enabled with a value of 100.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Generally, the default value of 100 allows you to easily define a particular path as less preferable than paths with no local preference attribute. The preference is sent to all networking devices in the local autonomous system.
Examples
The following example shows how to raise the default local preference value from the default of 100 to 200:
RP/0/RP0/CPU0:router(config)# router bgp 200RP/0/RP0/CPU0:router(config-bgp)# bgp default local-preference 200bgp enforce-first-as disable
To disable the software from enforcing the first autonomous system path (known as the AS path) of a route received from an external Border Gateway Protocol (eBGP) peer to be the same as the configured remote autonomous system, use the bgp enforce-first-as disable command in router configuration mode. To re-enable enforcing the first AS path of a received route from an eBGP peer to be the same as the remote autonomous system, use the no form of this command.
bgp enforce-first-as disable
no bgp enforce-first-as disable
Syntax Description
This command has no arguments or keywords.
Defaults
By default, the software requires the first autonomous system (in the AS path) of a route received from an eBGP peer to be the same as the remote autonomous system configured.
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
By default, the software ignores any update received from an eBGP neighbor that does not have the autonomous system configured for that neighbor at the beginning of the AS path. When configured, the command applies to all eBGP peers of the router.
Examples
The following example shows a configuration in which incoming updates from eBGP neighbors are not checked to ensure the first AS number in the AS path is the same as the configured AS number for the neighbor:
RP/0/RP0/CPU0:router(config)# router bgp 100RP/0/RP0/CPU0:router(config-bgp)# bgp enforce-first-as disableRelated Commands
bgp fast-external-fallover disable
To disable immediately resetting the Border Gateway Protocol (BGP) sessions of any directly adjacent external peers if the link used to reach them goes down, use the bgp fast-external-fallover disable command in router configuration mode. To disable this function and perform an immediate reset of BGP sessions when a link between peers is lost, use the no form of this command.
bgp fast-external-fallover disable
no bgp fast-external-fallover disable
Syntax Description
Defaults
BGP sessions of any directly adjacent external peers are immediately reset if the link used to reach them goes down.
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
By default, BGP sessions of any directly adjacent external peers are immediately reset, which allows the network to recover faster when links go down between BGP peers..
Examples
The following example shows how to disable the automatic resetting of BGP sessions:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# bgp fast-external-fallover disablebgp graceful-restart
To enable graceful restart support, use the bgp graceful-restart command in router configuration mode. To disable this function, use the no form of this command.
bgp graceful-restart
no bgp graceful-restart
Syntax Description
This command has no arguments or keywords.
Defaults
Graceful restart support is not enabled.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the bgp graceful-restart command to enable graceful restart functionality on the router, and also to advertise graceful restart to neighboring routers.
Note
When graceful restart is enabled, the BGP graceful restart capability is negotiated with neighbors in the BGP OPEN message when the session is established. If the neighbor also advertises support for graceful restart, then graceful restart is activated for that neighbor session. If the neighbor does not advertise support for graceful restart, then graceful restart is not activated for that neighbor session even though it is enabled locally.
If you enter the bgp graceful-restart command after some BGP sessions are established, you must restart those sessions before graceful restart takes effect. Use the clear bgp command to restart sessions.
Examples
The following example shows how to enable graceful restart:
RP/0/RP0/CPU0:router(config)# router bgp 3RP/0/RP0/CPU0:router(config-bgp)# bgp graceful-restartRelated Commands
bgp graceful-restart graceful-reset
To invoke a graceful restart when configuration changes force a peer reset, use the bgp graceful-restart graceful-reset command in router configuration mode. To disable this function, use the no form of this command.
bgp graceful-restart graceful-reset
no bgp graceful-restart graceful-reset
Syntax Description
This command has no arguments or keywords.
Defaults
Graceful restart is not invoked when a configuration change forces a peer reset.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
BGP graceful restart must be enabled using the bgp graceful-restart command before enabling graceful reset using the bgp graceful-restart graceful-reset command.
Examples
The following example shows how to enable graceful reset:
RP/0/RP0/CPU0:router(config)# router bgp 3RP/0/RP0/CPU0:router(config-bgp)# bgp graceful-restart graceful-resetRelated Commands
Enables a graceful restart.
Displays entries in the BGP routing table.
Displays information about BGP connections to neighbors.
Displays BGP process information.
bgp graceful-restart purge-time
To specify the maximum time before stale routes are purged from the routing information base (RIB) when the local BGP process restarts, use the bgp graceful-restart purge-time command in router configuration mode. To set the purge timer time to its default value, use the no form of this command.
bgp graceful-restart purge-time seconds
no bgp graceful-restart purge-time seconds
Syntax Description
Defaults
seconds: 600
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
BGP graceful restart must be enabled using the bgp graceful-restart command before setting the purge time using the bgp graceful-restart purge-time command.
Examples
The following example shows how to change the BGP purge time to 800 seconds:
RP/0/RP0/CPU0:router(config)# router bgp 3RP/0/RP0/CPU0:router(config-bgp)# bgp graceful-restart purge-time 800Related Commands
Enables a graceful restart.
Displays entries in the BGP routing table.
Displays information about BGP connections to neighbors.
Displays BGP process information.
bgp graceful-restart restart-time
To specify a user-predicted local BGP process maximum restart time, which is advertised to neighbors during session establishment, use the bgp graceful-restart restart-time command in router configuration mode. To set this restart time to its default value, use the no form of this command.
bgp graceful-restart restart-time seconds
no bgp graceful-restart restart-time seconds
Syntax Description
Defaults
seconds: 120
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
BGP graceful restart must be enabled using the bgp graceful-restart command before enabling graceful reset using the bgp graceful-restart purge-time command.
Examples
The following example shows how to change the BGP graceful restart time to 400 seconds:
RP/0/RP0/CPU0:router(config)# router bgp 3RP/0/RP0/CPU0:router(config-bgp)# bgp graceful-restart restart-time 400Related Commands
Enables a graceful restart.
Displays entries in the BGP routing table.
Displays information about BGP connections to neighbors.
Displays BGP process information.
bgp graceful-restart stalepath-time
To specify the maximum time to wait for an End-of-RIB message after a neighbor restarts, use the bgp graceful-restart stalepath-time command in router configuration mode. To set the stalepath timer time to its default value, use the no form of this command.
bgp graceful-restart stalepath-time seconds
no bgp graceful-restart stalepath-time seconds
Syntax Description
Defaults
seconds: 360
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
BGP graceful restart must be enabled using the bgp graceful-restart command before setting the stalepath time using the bgp graceful-restart stalepath-time command.
If the stalepath time is exceeded before an End-of-RIB message is received from a neighbor, paths learned from the neighbor are purged from the BGP routing table.
Examples
The following example shows how to change the stalepath time to 750 seconds:
RP/0/RP0/CPU0:router(config)# router bgp 3RP/0/RP0/CPU0:router(config-bgp)# bgp graceful-restart stalepath-time 750Related Commands
Enables a graceful restart.
Displays entries in the BGP routing table.
Displays information about BGP connections to neighbors.
Displays BGP process information.
bgp log neighbor changes disable
To disable logging of Border Gateway Protocol (BGP) neighbor resets, use the bgp log neighbor changes disable command in router configuration mode. To re-enable logging of BGP neighbor resets, use the no form of this command.
bgp log neighbor changes disable
no bgp log neighbor changes disable
Syntax Description
This command has no arguments or keywords.
Defaults
BGP neighbor changes are logged.
Command Modes
Router configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Logging of BGP neighbor status changes (up or down) and resets is used for troubleshooting network connectivity problems and measuring network stability. Unexpected neighbor resets might indicate high error rates or high packet loss in the network, and should be investigated.
Status change message logging does not substantially affect performance, unlike, for example, enabling per-BGP update debugging. If the UNIX syslog facility is enabled, messages are sent by the software to the UNIX host running the syslog daemon so that the messages can be stored and archived on disk. If the UNIX syslog facility is not enabled, the status change messages are kept in the internal buffer of the router, and are not stored to disk. You can set the size of this buffer, which is dependent upon the available RAM, using the logging buffered command.
The neighbor status change messages are not tracked if the bgp log neighbor changes disabled command is disabled, except for the last reset reason, which is always available as output of the show bgp neighbors command.
Up and down messages for BGP neighbors are logged by the software by default. Use the bgp log neighbor changes disable command to stop logging BGP neighbor changes.
Use the show logging command to display the log for the BGP neighbor changes.
Examples
The following example shows how to prevent the logging of neighbor changes for BGP:
RP/0/RP0/CPU0:router(config)# router bgp 65530RP/0/RP0/CPU0:router(config-bgp)# bgp log neighbor change disableRelated Commands
logging buffered
Logs messages to an internal buffer.
Displays information about the TCP and BGP connections to neighbors.
show logging
Displays the state of logging (syslog).
bgp maximum neighbor
To control the maximum number of neighbors that can be configured on the router, use the bgp maximum neighbor command in router configuration mode. To set the neighbor limit to the default value, use the no form of this command.
bgp maximum neighbor limit
no maximum log neighbor limit
Syntax Description
Defaults
Default limit is 1024
Command Modes
Router configuration
Command History
Release 3.2
This command was first supported on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Any attempt to configure the neighbor limit below 1 or above 1500 will fail. Similarly, attempt to configure the limit below the number of neighbor that is already configured will also fail.
Examples
The following example shows how to change the default maximum neighbor limit and set it to 1200:
RP/0/RP0/CPU0:router(config)# router bgp 65530RP/0/RP0/CPU0:router(config-bgp)# bgp maximum neighbor 1200bgp redistribute-internal
To allow the redistribution of internal Border Gateway Protocol (iBGP) routes into an Interior Gateway Protocol (IGP), such as Intermediate System-to-Intermediate System (IS-IS) or Open Shortest Path First (OSPF), use the bgp redistribute-internal command in router configuration mode. To disable the redistribution of iBGP routes into IGPs, use the no form of this command.
bgp redistribute-internal
no bgp redistribute-internal
Syntax Description
This command has no arguments or keywords.
Defaults
By default, iBGP routes are not redistributed into IGPs.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use of the bgp redistribute-internal command requires the clear route * command to be issued to reinstall all BGP routes into the IP routing table.
Caution
Examples
The following example shows how to redistribute iBGP routes into OSPF:
RP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# bgp redistribute-internalRP/0/RP0/CPU0:router(config-bgp)# exitRP/0/RP0/CPU0:router(config)# router ospf area1RP/0/RP0/CPU0:router(config-router)# redistribute bgp 1RP/0/RP0/CPU0:router(config-router)# commitRelated Commands
bgp router-id
To configure a fixed router ID for a Border Gateway Protocol (BGP)-speaking router, use the bgp router-id command in router configuration mode. To disable a fixed route ID, use the no form of this command.
bgp router-id {ip-address | interface-type interface-instance}
no bgp router-id
Syntax Description
Defaults
If no router ID is configured in BGP, BGP attempts to use the global router ID if one is configured and available. Otherwise, BGP uses the highest IP address configured on a loopback interface.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
If you do not use the bgp router-id command to configure a router ID, and an IP address is not configured on any loopback interface or no global router ID is configured, BGP neighbors remain down.
We recommend that an IP address instead of an interface be used to configure the router ID. If you choose to specify an interface instead of an IP address, BGP is not able to obtain a router ID and a session is not established if the interface does not exist, is down, or has no IPv4 address assigned to it.
For more details on router IDs, see the Cisco IOX XR Routing Configuration Guide.
Examples
The following example shows how to configure the local router with the router ID of 192.168.70.24:
RP/0/RP0/CPU0:router(config)# router bgp 100RP/0/RP0/CPU0:router(config-bgp)# bgp router-id 192.168.70.24Related Commands
bgp scan-time
To configure scanning intervals of Border Gateway Protocol (BGP)-speaking networking devices, use the bgp scan-time command in router configuration mode and address family configuration mode. To restore the scanning interval to its default value, use the no form of this command.
bgp scan-time seconds
no bgp scan-time
Syntax Description
Defaults
The default scanning interval is 60 seconds.
Command Modes
Address family configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the bgp scan-time command to change how frequently the software processes scanner tasks, such as conditional advertisement, dynamic MED changes, and periodic maintenance tasks.
Examples
The following example shows how to set the scanning interval for IPv4 unicast to 20 seconds:
RP/0/RP0/CPU0:router(config)# router bgp 64500RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# bgp scan-time 20Related Commands
bgp update-delay
To set the maximum initial delay for a Border Gateway Protocol (BGP)-speaking router to send the first updates, use the bgp update-delay command in router configuration mode. To restore the initial delay to its default value, use the no form of this command.
bgp update-delay seconds [always]
no bgp update-delay
Syntax Description
Defaults
120 seconds
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
When BGP is started, it waits a specified period of time for its neighbors to establish peering sessions and to complete sending their initial updates. After all neighbors complete their initial updates, or after the update delay timer expires, the best path is calculated for each route, and the software starts sending advertisements out to its peers. This behavior improves convergence time. If the software were to advertise a route as soon as it learned it, it would have to readvertise the route each time it learned a new path that was preferred over all previously learned paths.
Use the bgp update-delay command to tune the maximum time the software waits after the first neighbor is established until it starts calculating best paths and sending out advertisements.
Examples
The following example shows how to set the maximum initial delay to 240 seconds:
RP/0/RP0/CPU0:router(config)# router bgp 64530RP/0/RP0/CPU0:router(config-bgp)# bgp update-delay 240bgp write-limit
To modify the upper bounds on update message queue lengths or to enable desynchronization, use the bgp write-limit command in router configuration mode. To return the bounds to their default values and to disable desynchronization, use the no form of this command.
bgp write-limit group-limit global-limit [desynchronize]
no bgp write-limit group-limit global-limit [desynchronize]
Syntax Description
Defaults
group-limit: 5000
global-limit: 25000
Desynchronization is off.Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the bgp write-limit command to configure both a per-update group and a global limit on the number of messages the software queues when updating peers. Increasing these limits can result in faster Border Gateway Protocol (BGP) convergence, but also may result in higher memory use during convergence. In addition, this command can be used to enable desynchronization. Desynchronization can decrease memory use and speed up convergence for the fastest neighbors if one or more neighbors in an update group process updates significantly slower than other neighbors in the same group. However, enabling desynchronization can cause a significant degradation in overall convergence time, especially if the router is experiencing high CPU utilization. For this reason, enabling desynchronization is discouraged.
Examples
The following example shows how to configure BGP to operate with a per-update group limit of 9,000 messages and a global limit of 27,000 messages:
RP/0/RP0/CPU0:router(config)# router bgp 65000RP/0/RP0/CPU0:router(config-bgp)# bgp write-limit 9000 27000capability orf prefix-list
To advertise prefix list-based Outbound Route Filter (ORF) capability to the Border Gateway Protocol (BGP) peer, use the capability orf prefix-list command in the appropriate configuration mode. To remove the capability orf prefix-list command from the configuration file and restore the system to its default condition in which the software does not advertise the capability, use the no form of this command.
capability orf prefix-list {receive | send | both | none}
no capability orf prefix-list
Syntax Description
Defaults
The routing device does not receive or send route prefix filter lists.
Command Modes
Address family group configuration
Neighbor address family configuration
Neighbor group address family configurationCommand History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
The advertisement of the prefix list ORF capability by a BGP speaker indicates whether the speaker can send prefix lists to the specified neighbor and whether it accepts prefix lists from the neighbor. The speaker sends a prefix list if it indicated the ability to send them, and if the neighbor indicated it was willing to accept them. Similarly, the neighbor sends a prefix list to the speaker if it indicated the ability to send them and the speaker indicated the willingness to accept them.
Note
If the neighbor sends a prefix list and the speaker accepts it, the speaker applies the received prefix list, plus any locally configured outbound filters, to limit its outbound routing updates to the neighbor. Increased filtering prevents unwanted routing updates between neighbors and reduces resource requirements for routing update generation and processing.
Use the capability orf prefix-list command to set whether to advertise send and receive capabilities to the specified neighbor.
Note
If this command is configured for a neighbor group or neighbor address family group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Note
Examples
The following example shows the local BGP speaker advertising that the speaker is willing to accept an ORF prefix list from its neighbor:
RP/0/RP0/CPU0:# configureRP/0/RP0/CPU0:(config)# router bgp 65530RP/0/RP0/CPU0:(config-bgp)# neighbor 10.0.101.1RP/0/RP0/CPU0:(config-bgp-nbr)# remote-as 65534RP/0/RP0/CPU0:(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:(config-bgp-nbr-af)# capability orf prefix-list receiveThe following example shows how to configure neighbor group orf to advertise ORF send capabilities:
RP/0/RP0/CPU0:# configureRP/0/RP0/CPU0:(config)# router bgp 65530RP/0/RP0/CPU0:(config-bgp)# neighbor-group orfRP/0/RP0/CPU0:(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:(config-bgp-nbr-af)# capability orf prefix-list sendThe following example shows how to configure af-group orf to advertise ORF send and receive capabilities:
RP/0/RP0/CPU0:# configureRP/0/RP0/CPU0:(config)# router bgp 65000RP/0/RP0/CPU0:(config-bgp)# af-group orf address-family ipv4 unicastRP/0/RP0/CPU0:(config-bgp-afgrp)# capability orf prefix-list bothRelated Commands
clear bgp
To reset a group of Border Gateway Protocol (BGP) neighbors, use the clear bgp command in EXEC mode.
clear bgp {* | ip-address | as-number | external} [graceful]
Syntax Description
Defaults
No default behavior or value
Command Modes
EXEC
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the clear bgp command to reset the sessions of the specified group of neighbors (hard reset); it removes the TCP connection to the neighbor, removes all routes received from the neighbor from the BGP table, and then re-establishes the session with the neighbor.
If the graceful keyword is specified, the routes from the neighbor are not removed from the BGP table immediately, but are marked as stale. After the session is re-established, any stale route that has not been received again from the neighbor is removed.
Examples
The following example shows how to hard reset neighbor 10.0.0.1:
RP/0/RP0/CPU0:router# clear bgp 10.0.0.1The following example shows how to hard reset all neighbors with a graceful restart:
RP/0/RP0/CPU0:router# clear bgp * gracefulRelated Commands
clear bgp dampening
To clear Border Gateway Protocol (BGP) route dampening information and unsuppress the suppressed routes, use the clear bgp dampening command in EXEC mode.
clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} dampening [ip-address/mask-length]
Syntax Description
Defaults
If no IP address is specified, dampening information for all routes is cleared.
Command Modes
EXEC
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Examples
The following example shows how to clear the route dampening information for all 172.20.0.0/16 IPv4 multicast paths:
RP/0/RP0/CPU0:router# clear bgp ipv4 multicast dampening 172.20.0.0/16Related Commands
Enables BGP route dampening or changes various BGP route dampening factors.
Displays BGP dampened routes.
clear bgp flap-statistics
To clear Border Gateway Protocol (BGP) flap counts for a specified group of routes, use the clear bgp flap-statistics command in EXEC mode.
clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} flap-statistics [regexp regexp | route-policy route-policy-name | network/mask-length | ip-address]
Syntax Description
Defaults
No default behavior or value
Command Modes
EXEC
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Examples
The following example shows how to clear the flap count for all routes (in all address families) originating in autonomous system 1:
RP/0/RP0/CPU0:router# clear bgp all all flap-statistics regexp _1$The following example shows how to clear the flap count for all IPv4 unicast routes received from neighbor 172.20.1.1:
RP/0/RP0/CPU0:router# clear bgp ipv4 unicast flap-statistics 172.20.1.1clear bgp peer-drops
To clear the connection-dropped counter, use the clear bgp peer-drops command in EXEC mode.
clear bgp peer-drops {* | ip-address}
Syntax Description
Defaults
No default behavior or value
Command Modes
EXEC
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Examples
The following example shows how to clear the connection-dropped counter for all BGP neighbors:
RP/0/RP0/CPU0:router# clear bgp peer-drops *Related Commands
clear bgp performance-statistics
To clear the performance statistics for all address families, use the clear bgp performance-statistics command.
clear bgp performance-statistics
Syntax Description
This command has no arguments or keywords.
Defaults
No default behavior or value
Command Modes
EXEC
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Examples
The following example shows how to clear the performance statistics for all address families:
RP/0/RP0/CPU0:router# clear bgp performance-statisticsclear bgp self-originated
To clear Border Gateway Protocol (BGP) routes that are self-originated, use the clear bgp self-originated command in EXEC mode.
clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} self-originated
Syntax Description
Defaults
No default behavior or value
Command Modes
EXEC
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Self-originated routes are routes locally originated by the network command, redistribute command, or aggregate-address command.
Examples
The following example shows how to clear self-originated IPv4 routes:
RP/0/RP0/CPU0:router# clear bgp ipv4 unicast self-originatedRelated Commands
clear bgp shutdown
To clear all Border Gateway Protocol (BGP) neighbors that shut down due to low memory, use the clear bgp command in EXEC mode.
clear bgp shutdown
Syntax Description
This command has no arguments or keywords
Defaults
No default behavior or value
Command Modes
EXEC
Command History
Release 3.2
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Examples
The following example shows how to clear all shut-down BGP neighbors:
RP/0/RP0/CPU0:router# clear bgp shutdownRelated Commands
Displays entries in the BGP routing table.
Displays information about the TCP and BGP connections to neighbors.
clear bgp soft
To soft reset a group of Border Gateway Protocol (BGP) neighbors, use the clear bgp soft command in EXEC mode.
clear bgp {ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {unicast | multicast | all}} {* | ip-address | as-number | external} soft [in [prefix-filter] | out]
Syntax Description
Defaults
No default behavior or value
Command Modes
EXEC
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the clear bgp soft command to trigger a soft reset of the specified address families for the specified group of neighbors. This command is useful if you change the inbound or outbound policy for the neighbors, or any other configuration that affects the sending or receiving of routing updates.
If an outbound soft reset is triggered, BGP resends all routes for the address family to the given neighbors.
If an inbound soft reset is triggered, BGP by default sends a REFRESH request to the neighbor, if the neighbor has advertised the ROUTE_REFRESH capability. To determine whether the neighbor has advertised the ROUTE_REFRESH capability, use the show bgp neighbors command, and look for the following line of output:
Received route refresh capability from peer.If the neighbor does not support route refresh, but the soft-reconfiguration inbound command is configured for the neighbor, then BGP uses the routes cached as a result of the soft-reconfiguration inbound command to perform the soft reset.
If you want BGP to use the cached routes even if the neighbor supports route refresh, you can use the always keyword when configuring the soft-reconfiguration inbound command.
If the neighbor does not support route refresh and the soft-reconfiguration inbound command is not configured, then inbound soft reset is not possible. In this case, an error is printed.
Note
Examples
The following example shows how to trigger an inbound soft clear for IPv4 unicast routes received from neighbor 10.0.0.1:
RP/0/RP0/CPU0:router# clear bgp ipv4 unicast 10.0.0.1 soft inRelated Commands
default-information originate (BGP)
To allow origination of a default route to be redistributed into the Border Gateway Protocol (BGP) from another protocol, use the default-information originate command in router configuration mode. To disable this function, use the no form of this command.
default-information originate
no default-information originate
Syntax Description
This command has no arguments or keywords.
Defaults
BGP does not permit redistribution of a default route into BGP.
Command Modes
Router configuration mode
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the redistribute command to redistribute routes from another protocol into BGP. By default, if these routes include the default route (0.0.0.0/0 for IPv4 or ::/0 for IPv6), the default route is ignored. Use the default-information originate command to change this behavior so that the default route is not ignored and is redistributed into BGP along with the other routes for the protocol being redistributed.
Examples
The following example shows how to configure BGP to redistribute the default route into BGP:
RP/0/RP0/CPU0:router(config)# router bgp 164RP/0/RP0/CPU0:router(config-bgp)# default-information originateRelated Commands
default-metric (BGP)
To set default metric values for the Border Gateway Protocol (BGP), use the default-metric command in router configuration mode. To disable metric values, use the no form of this command.
default-metric value
no default-metric
Syntax Description
Defaults
A metric is not sent.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the default-metric command to set the Multi Exit Discriminator (MED) to advertise to peers for routes that do not already have a metric set (routes that were received with no MED attribute).
Examples
The following example shows how to set the BGP default metric:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# default-metric 10default-originate
To cause a Border Gateway Protocol (BGP) speaker (the local router) to send the default route 0.0.0.0/0 to a neighbor for use as a default route, use the default-originate command in neighbor address family configuration mode. To disable this function, use the no form of this command.
default-originate [disable | route-policy route-policy-name]
no default-originate
Syntax Description
Defaults
The default route is not advertised to BGP neighbors.
Command Modes
Neighbor address family configuration
Neighbor group address family configuration
Address family groupCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
The default-originate command does not require the presence of the default route (0.0.0.0/0 for IPv4 or ::/0 for IPv6) in the local router. When the default-originate command is used with a route policy, the default route is advertised if any route in the BGP table matches the policy.
Examples
The following example shows how to unconditionally advertise the route 0.0.0.0/0 to the neighbor 172.20.2.3:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.2.3RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 200RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# default-originateThe following example shows how to advertise the route 0.0.0.0/0 to the neighbor 172.20.2.3 only if a route exists in the BGP table that matches the route policy called default-default-policy:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.2.3RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 200RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# default-originate route-policy default-default-policyRelated Commands
description (BGP)
To annotate a neighbor, neighbor group, or session group, use the description command in neighbor configuration, neighbor group configuration, or session group configuration mode. To remove the annotation, use the no form of this command.
description text
no description
Syntax Description
Defaults
No comment or description exists.
Command Modes
Neighbor group configuration
Neighbor configuration
Session group configurationCommand History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported On the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the description command to provide a description of a neighbor, neighbor group, or session group. The description is used to save user comments and does not affect software function.
Examples
The following example shows how to configure the description "Our best customer" on the neighbor 192.168.13.4:
RP/0/RP0/CPU0:router# configureRP/0/RP0/CPU0:router(config)# router bgp 65000RP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.13.4RP/0/RP0/CPU0:router(config-bgp-nbr)# description Our best customerRP/0/RP0/CPU0:router# show running-config router bgp 65000router bgp 65000neighbor 192.168.13.4remote-as 65001description Our best customerdistance bgp
To allow the use of external, internal, and local administrative distances that could be used to prefer one class of routes over another, use the distance bgp command in address family configuration mode. To disable the use of administrative distances, use the no form of this command.
distance bgp external-distance internal-distance local-distance
no distance bgp
Syntax Description
Defaults
external-distance: 20
internal-distance: 200
local-distance: 200Command Modes
Address family configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the distance bgp command if another protocol is known to be able to provide a better route to a node than was actually learned using external BGP, or if some internal routes should be preferred by BGP.
Caution
An administrative distance is a rating of the trustworthiness of a routing information source. Numerically, an administrative distance is an integer from 1 to 255. In general, the higher the value, the lower the trust rating. An administrative distance of 255 means the routing information source cannot be trusted at all and should be ignored.
Examples
The following example shows that iBGP routes are preferable to locally generated routes, so the administrative distance values are set accordingly:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# distance bgp 20 20 200Related Commands
Defines the administrative distance assigned to routes discovered by the IS-IS protocol.
Defines OSPF route administrative distances based on route type.
dmz-link-bandwidth
To originate a demilitarized zone (DMZ) link bandwidth extended community for the link to an eBGP neighbor, use the dmz-link-bw command in the appropriate configuration mode. To cease origination of the DMZ link bandwidth extended community, use the no form of this command.
dmz-link-bandwidth [disable]
no dmz-link-bandwidth
Syntax Description
disable
(Optional) Prevents the dmz-link-bandwidth command from being inherited from a parent group.
Defaults
BGP does not originate the DMZ link bandwidth extended community.
Command Modes
Neighbor configuration
Neighbor group configuration
Session group configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the dmz-link-bandwidth command to advertise the bandwidth of links that are used to exit an autonomous system.
If this command is configured for a neighbor group or session group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Examples
The following example shows how to advertise the bandwidth of links on router bgp 1:
RP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# neighbor 45.67.89.01RP/0/RP0/CPU0:router(config-bgp-nbr)# dmz-link-bandwidthRelated Commands
Creates a neighbor group and enters neighbor group configuration mode.
Creates a session group and enters session group configuration mode.
ebgp-multihop
To accept and attempt Border Gateway Protocol (BGP) connections to external peers residing on networks that are not directly connected, use the ebgp-multihop command in the appropriate configuration mode. To disable connections to external peers and allow only direct connections between neighbors, use the no form of this command.
ebgp-multihop [ttl-value]
no ebgp-multihop
Syntax Description
Defaults
The external BGP (eBGP) multihop TTL default value is 1 if the ebgp-multihop command is not specified. If the command is specified but a TTL value is not given, the default is 255.
Command Modes
Neighbor configuration
Neighbor group configuration
Session group configurationCommand History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the ebgp-multihop command to enable multihop peerings with external BGP neighbors. The BGP protocol states that external neighbors must be directly connected (one hop away). The software enforces this by default; however, the ebgp-multihop command can be used to override this behavior.
If this command is configured for a neighbor group or session group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Examples
The following example shows how to allow a BGP connection to neighbor 172.20.16.6 of up to 255 hops away:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.16.6RP/0/RP0/CPU0:router(config-bgp-nbr)# ebgp-multihopRelated Commands
Creates a neighbor group and enters neighbor group configuration mode.
Creates a session group and enters session group configuration mode.
local-as
To allow customization of the autonomous system number for external Border Gateway Protocol (eBGP) neighbor peerings, use the local-as command in the appropriate configuration mode. To disable customization of local autonomous system values for eBGP neighbor peerings, use the no form of this command.
local-as {autonomous-system-number [no-prepend] | disable}
no local-as [autonomous-system-number [no-prepend] | disable]
Syntax Description
Defaults
The BGP autonomous system number specified in the router bgp command is used, except when confederations are in use. The confederation autonomous system is used for external neighbors in an autonomous system that is not part of the confederation.
Command Modes
Neighbor configuration
Neighbor group configuration
Session group configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
You can specify the autonomous system number the local BGP uses to peer with each neighbor. The autonomous system number specified with this command cannot be the local BGP autonomous system number (specified with the router bgp command) or the autonomous system number of the neighbor (specified with the remote-as command). This command cannot be specified for internal neighbors or for external neighbors in an autonomous system that is part of a confederation.
If this command is configured for a neighbor group or session group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Examples
The following example shows BGP using autonomous system 30 for the purpose of peering with neighbor 172.20.1.1:
RP/0/RP0/CPU0:router(config)# router bgp 140RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 300RP/0/RP0/CPU0:router(config-bgp-nbr)# local-as 30Related Commands
Creates a neighbor group and enters neighbor group configuration mode.
Creates a session group and enters session group configuration mode.
maximum-paths (BGP)
To control the maximum number of parallel routes that Border Gateway Protocol (BGP) installs in the routing table, use the maximum-paths command in address family configuration mode. To set the maximum number of parallel routes the software installs to the default value, use the no form of this command.
maximum-paths {ebgp | ibgp} maximum
no maximum-paths {ebgp | ibgp} maximum
Syntax Description
ebgp
Specifies external BGP multipath peers.
ibgp
Specifies internal BGP multipath peers.
maximum
Maximum number of parallel routes that BGP installs in the routing table. Range is 2 to 8
Defaults
One path
Command Modes
Address family configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the maximum-paths command to allow the BGP protocol to install multiple paths into the routing table for each prefix. Multiple paths are installed for external peers that are from the same autonomous system and are equal cost (according to the BGP best path algorithm). Similarly, multiple paths are installed for internal peers that are equal cost (based on the BGP best path algorithm).
Examples
The following example shows how to allow a maximum of four paths to a destination installed into the IPv4 unicast routing table:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# maximum-paths ebgp 4maximum-prefix
To control how many prefixes can be received from a neighbor, use the maximum-prefix command in the appropriate configuration mode. To set the prefix limits to the default values, use the no form of this command.
maximum-prefix maximum [threshold] [warning-only]
no maximum-prefix
Syntax Description
Defaults
When this command is not specified, the following defaults apply:
IPv4 unicast: 524,288 prefixes
IPv4 multicast: 131,072 prefixes
IPv6 unicast: 131,072 prefixes
The default threshold when a warning message is generated is 75 percent.Command Modes
Address family group configuration
Neighbor address family configuration
Neighbor group address family configurationCommand History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the maximum-prefix command to configure a maximum number of prefixes that a BGP router is allowed to receive from a neighbor. It adds another mechanism (besides routing policy) to control prefixes received from a peer.
When the number of received prefixes exceeds the maximum number configured, the software terminates the peering, by default, after sending a cease notification to the neighbor. However, if the warning-only keyword is configured, the software writes only a log message, but continues peering with the sender. If the peer is terminated, the peer stays down until the clear bgp command is issued.
This command takes effect immediately if configured on an established neighbor unless the number of prefixes received from the neighbor already exceeds the configured limits.
If this command is configured for a neighbor group or neighbor address family group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Examples
The following example shows the maximum number of IP Version 4 (IPv4) unicast prefixes allowed from the neighbor at 192.168.40.24 set to 1000:
RP/0/RP0/CPU0:router(config-bgp)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.40.24RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# maximum-prefix 1000Related Commands
neighbor (BGP)
To enter neighbor configuration mode for configuring Border Gateway Protocol (BGP) routing sessions, use the neighbor command in router configuration mode. To delete all configuration for a neighbor and terminate peering sessions with the neighbor, use the no form of this command.
neighbor ip-address
no neighbor ip-address
Syntax Description
Defaults
Neighbor mode is not specified.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
From router configuration mode, you can use this command to enter neighbor configuration mode.
From neighbor configuration mode, you can enter address family configuration for the neighbor by using the address-family command, which allows you to configure routing sessions for IP Version 4 and IP Version 6 address prefixes.
The neighbor command does not cause the neighbor to be configured and does not result in a peering to be established with the neighbor. To create the neighbor, you configure a remote autonomous system number by entering the remote-as command, or the neighbor can inherit a remote autonomous system from a neighbor group or session group if the use command is applied.
Unlike IPv4, IPv6 must be enabled before any IPv6 neighbors can be defined. Enable IPv6 in router configuration mode using the address-family command.
Note
The no form of this command causes the peering with the neighbor to be terminated and all configuration that relates to the neighbor to be removed.
Examples
The following example shows how to place the router in neighbor configuration mode for BGP routing process 1 and configure the neighbor IP address 172.168.40.24 as a BGP peer:
RP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.168.40.24RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 65000The following example shows how to enable IPv6 for BGP, then place the router in neighbor configuration mode for an IPv6 neighbor, 3000::1, and configure neighbor 3000::1 as a BGP peer:
RP/0/RP0/CPU0:router(config)# router bgp 100RP/0/RP0/CPU0:router(config-bgp)# address-family ipv6 unicastRP/0/RP0/CPU0:router(config-bgp-af)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 3000::1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 2002Related Commands
neighbor-group
To create a neighbor group and enter neighbor group configuration mode, use the neighbor-group command in router configuration mode. To remove a neighbor group and delete all configuration associated with the group, use the no form of this command.
neighbor-group name
no neighbor-group name
Syntax Description
Defaults
No neighbor group mode is specified.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
The neighbor-group command puts the router in neighbor group configuration mode and creates a neighbor group.
A neighbor group helps you apply the same configuration to one or more neighbors. After a neighbor group is configured, each neighbor can inherit the configuration through the use command. If a neighbor is configured to use a neighbor group, the neighbor, by default, inherits the entire configuration of the neighbor group, which includes the address family-independent and address family-specific configurations. The inherited configuration can be overridden if you directly configure commands for the neighbor or if you configure session groups or address family groups with the use command.
From neighbor group configuration mode, you can configure address family-independent parameters for the neighbor group. To enter address family-specific configuration for the neighbor group, use the address-family command when in the neighbor group configuration mode.
Note
The no form of this command ordinarily causes all configuration for the neighbor group to be removed. If using the no form would result in a neighbor losing its remote autonomous system number, the configuration is rejected. In this scenario, the neighbor configuration must be either removed or configured with a remote autonomous system number before the neighbor group configuration can be removed.
Note
Examples
The following example shows how to create a neighbor group called group1 that has IP Version 4 (IPv4) unicast and IPv4 multicast activated along with various configuration features. The neighbor group is used by neighbor 10.0.0.1 and neighbor 10.0.0.2, which allows them to inherit the entire group1 configuration.
RP/0/RP0/CPU0:router(config)# router bgp 65530RP/0/RP0/CPU0:router(config-bgp)# neighbor-group group1RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# remote-as 65535RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# advertisement-interval 2RP/0/RP0/CPU0:router(config-bgp-nbrgrp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# send-community-ebgpRP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# exitRP/0/RP0/CPU0:router(config-bgp-nbrgrp)# address-family ipv4 multicastRP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# next-hop-selfRP/0/RP0/CPU0:router(config-bgp-nbrgrp-af)# exitRP/0/RP0/CPU0:router(config-bgp-nbrgrp)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.0.1RP/0/RP0/CPU0:router(config-bgp-nbr)# use neighbor-group group1RP/0/RP0/CPU0:router(config-bgp-nbr)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.0.2RP/0/RP0/CPU0:router(config-bgp-nbr)# use neighbor-group group1RP/0/RP0/CPU0:router(config-bgp-nbr)# exitRelated Commands
network (BGP)
To specify that the Border Gateway Protocol (BGP) routing process should originate and advertise a local network to its neighbors, use the network command in address family configuration mode. To disable originating or advertising the network to neighbors, use the no form of this command.
network {ip-address/prefix-length | ip-address mask} [route-policy route-policy-name]
no network {ip-address/prefix-length | ip-address mask}
Syntax Description
Defaults
No networks are specified.
Command Modes
Address family configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Although most Interior Gateway Protocols (IGPs) use the network command to indicate the interfaces on which the routing protocol runs, the network command in BGP determines which local networks are originated by this router. A network specified with this command is originated and advertised to neighbors only if there exists an IGP route for the network in the routing table. That is, there must be a route learned using local or connected networks, static routing, or a dynamic IGP such as IS-IS or OSPF.
Other than the available system resources on the router, no limit exists on the number of network commands that can be configured.
Examples
The following example shows how to configure the local router to originate the IPv4 unicast network 172.20.0.0/16:
RP/0/RP0/CPU0:router(config)# router bgp 120RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# network 172.20.0.0/16Related Commands
Specifies a backdoor route to a BGP border router that provides better information about the network.
Redistributes routes from one routing domain into another routing domain.
network backdoor
To set the administrative distance on an external Border Gateway Protocol (eBGP) route to that of a locally sourced BGP route, causing it to be less preferred than an Interior Gateway Protocol (IGP) route, use the network backdoor command in address family configuration mode. To disable setting the administrative distance to the value for locally sourced BGP routes, use to no form of this command.
network {ip-address/prefix-length | ip-address mask} backdoor
no network {ip-address/prefix-length | ip-address mask} backdoor
Syntax Description
Defaults
No backdoor routes are installed.
Command Modes
Address family configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Configuring the network backdoor command does not cause BGP to originate a network, even if an IGP route for the network exists. Ordinarily, the backdoor network would be learned through both an eBGP and IGP. The BGP best path selection algorithm does not change when a network is configured as a backdoor network.
Examples
The following example shows IP Version 4 (IPv4) unicast network 192.168.40.0/24 configured as a backdoor network:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# network 192.168.40.0/24 backdoorRelated Commands
Specifies a local network that the BGP routing process should originate and advertise to its neighbors.
next-hop-self
To disable next-hop calculation and insert your own address in the next-hop field of Border Gateway Protocol (BGP) updates, use the next-hop-self command in the appropriate configuration mode. To enable next-hop calculation, use the no form of this command.
next-hop-self [disable]
no next-hop-self
Syntax Description
disable
(Optional) Allows next hop calculation override when this feature may be inherited from a neighbor group or address family group.
Defaults
When this command is not specified, the software calculates the next hop for BGP updates accepted by the router.
Command Modes
Address family group configuration
Neighbor address family configuration
Neighbor group address family configurationCommand History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the next-hop-self command to set the BGP next hop attribute of routes being advertised over a peering session to the local source address of the session.
This command is useful in nonmeshed networks (such as Frame Relay or X.25) where BGP neighbors may not have direct access to all other neighbors on the same IP subnet.
If this command is configured for a neighbor group or address family group, a neighbor using the group inherits the configuration. Configuring the command specifically for a neighbor overrides any inherited value.
Examples
The following example shows how to set the next hop of the update field for all IP Version 4 (IPv4) unicast routes advertised to neighbor 172.20.1.1 to an address of the local router:
RP/0/RP0/CPU0:router(config)# router bgp 140RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# next-hop-selfThe following example shows how to disable the next-hop-self command for neighbor 172.20.1.1. If not overridden, the next hop would be inherited from address family group group1:
RP/0/RP0/CPU0:router(config)# router bgp 140RP/0/RP0/CPU0:router(config-bgp)# af-group group1 address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-afgrp)# next-hop-selfRP/0/RP0/CPU0:router(config-bgp-afgrp)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# use af-group group1RP/0/RP0/CPU0:router(config-bgp-nbr-af)# next-hop-self disableRelated Commands
password
To enable Message Digest 5 (MD5) authentication on a TCP connection between two Border Gateway Protocol (BGP) neighbors, use the password command in the appropriate configuration mode. To disable MD5 authentication, use the no form of this command.
password {clear | encrypted} password
no password [clear password | encrypted password]
Syntax Descriptionr
Defaults
When this command is not specified in the appropriate configuration mode, MD5 authentication is not enabled on a TCP connection between two BGP neighbors.
Command Modes
Neighbor configuration
Neighbor group configuration
Session group configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Configure a password to enable authentication between two BGP peers. Use the password command to verify each segment sent on the TCP connection between the peers. The same password must be configured on both networking devices, otherwise a connection cannot be made. The authentication feature uses the MD5 algorithm. Specifying this command causes the software to generate and check the MD5 digest on every segment sent on the TCP connection.
Configuring a neighbor password does not cause the existing session for a neighbor to end. However, until the new password is configured on the remote router, the local BGP process does not receive keepalive messages from the remote device. If the password is not updated on the remote device by the end of the hold time, the session ends. The hold time can be changed using the timers command or the timers bgp command.
If this command is configured for a neighbor group or neighbor address family group, a neighbor using the group inherits the configuration. Values of commands configured specifically for a neighbor overrides inherited values.
Examples
The following example shows how to configure neighbor 172.20.1.1 to use MD5 authentication with the password password1:
RP/0/RP0/CPU0:router(config)# router bgp 140RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# password clear password1Related Commands
password-disable
To override any inherited password configuration from a neighbor group or session group for Border Gateway Protocol (BGP) neighbors, use the password-disable command in the appropriate configuration mode. To disable overriding any inherited password command, use the no form of this command.
password-disable
no password-disable
Syntax Description
This command has no arguments or keywords.
Defaults
Configured passwords for neighbor and session groups are inherited.
Command Modes
Neighbor configuration
Neighbor group configuration
Session group configurationCommand History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
If you specify a password on a neighbor group or session group, all users of the group inherit the password. Specifying a different password command specifically on a neighbor that uses the group overrides the inherited value. Specifying password-disable on a neighbor that uses the group disables password authentication for the neighbor.
Examples
The following example shows how to disable MD5 authentication for neighbor 172.20.1.1, preventing it from inheriting the password password1 from session group group1:
RP/0/RP0/CPU0:router(config)# router bgp 140RP/0/RP0/CPU0:router(config-bgp)# session-group group1RP/0/RP0/CPU0:router(config-bgp-sngrp)# password clear password1RP/0/RP0/CPU0:router(config-bgp-sngrp)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 2RP/0/RP0/CPU0:router(config-bgp-nbr)# use session-group group1RP/0/RP0/CPU0:router(config-bgp-nbr)# password-disableRelated Commands
prefix-list (BGP)
To use a prefix list to filter updates received from a neighbor, use the prefix-list command in the appropriate configuration mode. To disable filtering updates, use the no form of this command.
prefix-list prefix-listname in
no prefix-list prefix-listname in
Syntax Description
prefix-listname
Name of a prefix list.
in
Applies the prefix list to incoming advertisements to that neighbor.
Defaults
No BGP neighbor is used.
Command Modes
Address family group configuration
Neighbor address family configuration
Neighbor group address family configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
The use of prefix lists is one of two ways to filter Border Gateway Protocol (BGP) advertisements. The other way is to use routing policies by using the route-policy (BGP) command. It is not possible to configure both a routing policy and a prefix list on a neighbor in the same direction.
If Outbound Route Filter (ORF) capabilities have been exchanged with the neighbor, the inbound prefix list is sent to the neighbor using the ORF mechanism. See the capability prefix-list orf command for more information.
The prefix-list command configures a neighbor group or neighbor address family group. All neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Examples
The following example shows the prefix list named myRoutes applied to inbound IPv4 multicast routes advertised to neighbor 172.20.1.1:
RP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 multicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# prefix-list myRoutes inRelated Commands
receive-buffer-size
To set the size of the receive buffers for a Border Gateway Protocol (BGP) neighbor, use the receive-buffer-size command in the appropriate configuration mode. To remove the receive-buffer-size command from the configuration file and restore the system to its default condition in which the software uses the default size, use the no form of this command.
receive-buffer-size socket-size [bgp-size]
no receive-buffer-size
Syntax Description
socket-size
Size, in bytes, of the receive-side socket buffer. Range is 512 to 131072.
bgp-size
(Optional) Size, in bytes, of the receive buffer in BGP. Range is 512 to 131072.
Defaults
socket-size: 32,768 bytes
bgp-size: 4,032 bytesCommand Modes
Neighbor configuration
Neighbor group configuration
Session group configurationCommand History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the receive-buffer-size command to increase the buffer size when receiving updates from a neighbor. Using larger buffers can improve convergence time because it allows the software to process a larger number of packets simultaneously. However, allocating larger buffers consumes more memory on the router.
Note
If this command is configured for a neighbor group or session group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Examples
The following example shows how to set the receive buffer sizes for neighbor 172.20.1.1 to be 65,536 bytes for the socket buffer and 8192 bytes for the BGP buffer:
RP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# receive-buffer-size 65536 8192Related Commands
redistribute (BGP)
To redistribute routes from one routing domain into Border Gateway Protocol (BGP), use the redistribute command in address family configuration mode. To disable route redistribution, use the no form of this command.
Connected
redistribute connected [metric metric-value] [route-policy route-policy-name]
no redistribute connected [metric metric-value] [route-policy route-policy-name]
Intermediate System-to-Intermediate System
redistribute isis process-id [level {1 | 1-inter-area | 2}] [metric metric-value] [route-policy route-policy-name]
no redistribute isis process-id [level {1 | 1-inter-area | 2}] [metric metric-value] [route-policy route-policy-name]
Open Shortest Path First (OSPF)
redistribute ospf process-id [match {external [1 | 2] | internal | nssa-external [1 | 2]]} [metric metric-value] [route-policy route-policy-name]
no redistribute ospf process-id [match {external [1 | 2] | internal | nssa-external [1 | 2]]} [metric metric-value] [route-policy route-policy-name]
OSPFv3
redistribute ospfv3 process-id [match {external [1 | 2] | internal | nssa-external [1 | 2]]} [metric metric-value] [route-policy route-policy-name]
no redistribute ospfv3 process-id [match {external [1 | 2] | internal | nssa-external [1 | 2]]} [metric metric-value] [route-policy route-policy-name]
Static
redistribute static [metric metric-value] [route-policy route-policy-name]
no redistribute static [metric metric-value] [route-policy route-policy-name]
Syntax Description
Defaults
Route redistribution is disabled.
For IS-IS, the default is to redistribute Level 1 and Level 2 routes.
For OSPF, the default is to redistribute internal, external, and NSSA external routes of Type 1 and Type 2.
For OSPFv3, the default is to redistribute internal, external, and NSSA external routes of Type 1 and Type 2
By default, the Interior Gateway Protocol (IGP) metric is assigned to the route. For connected and static routes the default metric is 0.
metric metric-value: 0
match {internal | external [1 | 2] | nssa-external [1 | 2]}: If no match is specified, the default is to match all routes.Command Modes
Address family configuration
Command History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Note
Each instance of a protocol may be redistributed independently of the others. Changing or removing redistribution for a particular instance does not affect the redistribution capability of other protocols or other instances of the same protocol.
Networks specified using the network command are not affected by the redistribute command; that is, the routing policy specified in the network command takes precedence over the policy specified through the redistribute command.
Examples
The following example shows how to redistribute IP Version 4 (IPv4) unicast OSPF routes from OSPF instance 110 into BGP:
RP/0/RP0/CPU0:router(config)# router bgp 109RP/0/RP0/CPU0:router(config-bgp)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-af)# redistribute ospf 110Related Commands
Specifies a local network that the BGP routing process should originate and advertise to its neighbors.
remote-as (BGP)
To create a Border Gateway Protocol (BGP) neighbor and begin the exchange of routing information, use the remote-as command in the appropriate configuration mode. To delete the entry for the BGP neighbor, use the no form of this command.
remote-as autonomous-system-number
no remote-as [autonomous-system-number]
Syntax Description
Defaults
No BGP neighbors exist.
Command Modes
Neighbor configuration
Neighbor group configuration
Session group configurationCommand History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the remote-as command to create a neighbor and assign it a remote autonomous system number. A neighbor must have a remote autonomous system number before any other commands can be configured for it. Removing the remote autonomous system from a neighbor causes the neighbor to be deleted. You cannot remove the autonomous system number if the neighbor has other configuration.
Note
A neighbor specified with a remote autonomous system number that matches the autonomous system number specified in the router bgp command identifies the neighbor as internal to the local autonomous system. Otherwise, the neighbor is considered external.
Configuration of the remote-as command for a neighbor group or session group using the neighbor-group command or session-group command causes all neighbors using the group to inherit the characteristics configured with the command. Configuring the command directly for the neighbor overrides the value inherited from the group.
In the neighbor configuration submode, configuring use of a session group or neighbor group for which remote-as is configured creates a neighbor and assigns it an autonomous system number if the neighbor has not already been created.
Note
Examples
The following example shows how to assign autonomous system numbers on two neighbors, neighbor 10.0.0.1, (internal) and neighbor 192.168.0.1 (external), setting up a peering session that shares routing information between this router and each of these neighbors:
RP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.0.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.0.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 2The following example shows how to configure a session group called group2 with an autonomous system number 1. Neighbor 10.0.0.1 is created when it inherits the autonomous system number 1 from session group group2.
RP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# session-group group2RP/0/RP0/CPU0:router(config-bgp-sngrp)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-sngrp)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.0.1RP/0/RP0/CPU0:router(config-bgp-nbr)# use session-group group2Related Commands
remove-private-as
To remove private autonomous system numbers from autonomous system paths when generating updates to external neighbors, use the remove-private-as command in the appropriate configuration mode. To place the router in the default state in which it does not remove private autonomous system numbers, use the no form of this command.
remove-private-as [disable]
no remove-private-as
Syntax Description
disable
(Optional) Permits the feature to be disabled from a neighbor group or address family group instead of being inherited.
Defaults
When this command is not specified in the appropriate configuration mode, private autonomous system numbers are not removed from updates sent to external neighbors.
Command Modes
Address family group configuration
Neighbor address family configuration
Neighbor group address family configurationCommand History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
This feature is available for external BGP (eBGP) neighbors only.
When an update is passed to the external neighbor, the software drops any leading autonomous system sequence in the autonomous system path if the sequence contains only private autonomous system numbers and does not contain the autonomous system number of the neighbor.
If this command is used in a BGP confederation, the element following the confederation portion of the autonomous system path, if a sequence, is considered the leading sequence.
The private autonomous system values range from 64512 to 65535.
If this command is configured for a neighbor group or address family group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Examples
The following example shows a configuration that removes the private autonomous system number from the IP Version 4 (IPv4) unicast updates sent to 172.20.1.1:
RP/0/RP0/CPU0:router(config)# router bgp 140RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# remote-private-asThe following example shows how to disable the remove private autonomous system number feature for neighbor 172.20.1.1, preventing this feature from being automatically inherited from address family group group1:
RP/0/RP0/CPU0:router(config)# router bgp 140RP/0/RP0/CPU0:router(config-bgp)# af-group group1 address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-afgrp)# remove-private-asRP/0/RP0/CPU0:router(config-bgp-afgrp)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr# remote-private-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# use af-group group1RP/0/RP0/CPU0:router(config-bgp-nbr-af)# remove-private-as disableRelated Commands
route-policy (BGP)
To apply a routing policy to updates advertised to or received from a Border Gateway Protocol (BGP) neighbor, use the route-policy command in the appropriate configuration mode. To disable applying routing policy to updates, use the no form of this command.
route-policy route-policy-name {in | out}
no route-policy route-policy-name {in | out}
Syntax Description
route-policy-name
Name of route policy.
in
Applies policy to inbound routes.
out
Applies policy to outbound routes.
Defaults
No policy is applied.
Command Modes
Address family group configuration
Neighbor address family configuration
Neighbor group address family configurationCommand History
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the route-policy command to specify a routing policy for an inbound or outbound route. The policy can be used to filter routes or modify route attributes. The route-policy command is used to define a policy.
If the route-policy command is configured for a neighbor group or neighbor address family group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Examples
The following example shows how to apply the In-Ipv4 policy to inbound IP Version 4 (IPv4) unicast routes from neighbor 172.20.1.1:
RP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# route-policy In-Ipv4 inRelated Commands
route-reflector-client
To configure the router as a Border Gateway Protocol (BGP) route reflector and configure the specified neighbor as its client, use the route-reflector-client command in the appropriate configuration mode. To disable configuring the neighbor as a client, use the no form of this command.
route-reflector-client [disable]
no route-reflector-client
Syntax Description
disable
(Optional) Allows the configuration inherited from a neighbor group or address family group to be overridden.
Defaults
The neighbor is not treated as a route-reflector client.
Command Modes
Address family group configuration
Neighbor address family configuration
Neighbor group address family configurationCommand History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
This command is restricted to internal BGP (iBGP) neighbors only.
Use the route-reflector-client command to configure the local router as the route reflector and the specified neighbor as one of its clients. All neighbors configured with this command are members of the client group, and the remaining iBGP peers are members of the nonclient group for the local route reflector.
By default, all iBGP speakers in an autonomous system must be fully meshed with each other, and neighbors do not readvertise iBGP learned routes to other iBGP neighbors.
With route reflection, all iBGP speakers need not be fully meshed. An iBGP speaker, the route reflector, passes learned iBGP routes to some number of iBGP client neighbors. Learned iBGP routes eliminate the need for each router running BGP to communicate with every other device running BGP in the autonomous system.
The local router is a route reflector as long as it has at least one route reflector client.
If this command is configured for a neighbor group or neighbor address family group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Examples
The following example shows neighbor at 172.20.1.1 configured as a route reflector client for IP Version 4 (IPv4) unicast routes:
RP/0/RP0/CPU0:router(config)# router bgp 140RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 140RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# route-reflector-clientThe following example disables the route-reflector client for neighbor 172.20.1.1, preventing this feature from being automatically inherited from address family group group1:
RP/0/RP0/CPU0:router(config)# router bgp 140RP/0/RP0/CPU0:router(config-bgp)# af-group group1 address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-afgrp)# route-reflector-clientRP/0/RP0/CPU0:router(config-bgp-afgrp)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 140RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# use af-group group1RP/0/RP0/CPU0:router(config-bgp-nbr-af)# route-reflector-client disableRelated Commands
router bgp
To configure the Border Gateway Protocol (BGP) routing process, use the router bgp command in global configuration mode. To remove all BGP configurations and terminate the BGP routing process, use the no form of this command.
router bgp autonomous-system-number
no router bgp
Syntax Description
autonomous-system-number
Number that identifies the autonomous system in which the router resides. Range is 1 to 65535.
Defaults
No BGP routing process is enabled.
Command Modes
Global configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the router bgp command to set up a distributed routing core that automatically guarantees the loop-free exchange of routing information between autonomous systems.
Examples
The following example shows how to configure a BGP process for autonomous system 120:
RP/0/RP0/CPU0:router(config)# router bgp 120send-buffer-size
To set the size of the send buffers for a Border Gateway Protocol (BGP) neighbor, use the send-buffer-size command in the appropriate configuration mode. To set the size of the send buffers to the default values, use the no form of this command.
send-buffer-size socket-size [bgp-size]
no send-buffer-size
Syntax Description
socket-size
Size, in bytes, of the send-side socket buffer. Range is 4096 to 131072.
bgp-size
(Optional) Size, in bytes, of the BGP process send buffer. Range is 4096 to 131072.
Defaults
socket-size: 4096 bytes
bgp-size: 4096 bytes
Use the socket send-buffer-size command to change the defaults.Command Modes
Neighbor configuration
Neighbor group configuration
Session group configurationCommand History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the send-buffer-size command to increase the buffer size employed when sending updates to a neighbor. Using larger buffers can improve convergence time because the software can process more packets simultaneously. However, allocating larger buffers uses more memory on the router.
Note
If this command is configured for a neighbor group or session group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Examples
The following example shows how to set the send buffer sizes for neighbor 172.20.1.1 to be 8192 bytes for both the socket buffer and the BGP buffer:
RP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# send-buffer-size 8192 8192Related Commands
send-community-ebgp
To specify that community attributes should be sent to an external Border Gateway Protocol (eBGP) neighbor, use the send-community-ebgp command in the appropriate configuration mode. To disable sending community attributes to an eBGP neighbor, use the no form of this command.
send-community-ebgp [disable]
no send-community-ebgp
Syntax Description
disable
(Optional) Allows configuration inherited from a neighbor group or address family group to be overridden.
Defaults
Community attributes are not sent to eBGP neighbors.
Command Modes
Address family group configuration
Neighbor address family configuration
Neighbor group address family configurationCommand History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the send-community-ebgp command to control whether community attributes are sent to eBGP neighbors. It cannot be configured for iBGP neighbors. Communities are always sent to iBGP neighbors.
If this command is configured for a neighbor group or address family group, all neighbors using the group inherit the configuration. Configuring the command specifically for a neighbor overrides inherited values.
Examples
The following example shows how to disable the router that sends community attributes to neighbor 172.20.1.1 for IP Version 4 (IPv4) multicast routes:
RP/0/RP0/CPU0:router(config)# router bgp 140RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 multicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# send-community-ebgpThe following example shows how to disable the delivery of community attributes to neighbor 172.20.1.1, preventing this feature from being inherited from address family group group1:
RP/0/RP0/CPU0:router(config)# router bgp 140RP/0/RP0/CPU0:router(config-bgp)# af-group group1 address-family ipv4 multicastRP/0/RP0/CPU0:router(config-bgp-afgrp)# send-community-ebgpRP/0/RP0/CPU0:router(config-bgp-afgrp)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 multicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# use af-group group1RP/0/RP0/CPU0:router(config-bgp-nbr-af)# send-community-ebgp disableRelated Commands
send-extended-community-ebgp
To specify that extended community attributes should be sent to external Border Gateway Protocol (eBGP) neighbors, use the send-extended-community-ebgp command in the appropriate configuration mode. To disable sending extended community attributes to eBGP neighbors, use the no form of this command.
send-extended-community-ebgp [disable]
no send-extended-community-ebgp
Syntax Description
disable
(Optional) Allows configurations inherited from a neighbor group or address family group to be overridden.
Defaults
Extended community attributes are not sent to an eBGP neighbor.
Command Modes
Address family group configuration
Neighbor address family configuration
Neighbor group address family configurationCommand History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the send-extended-community-ebgp command to control whether extended community attributes are sent to eBGP neighbors. It cannot be used for iBGP neighbors. Extended communities are always sent to iBGP neighbors.
If this command is configured for a neighbor group or neighbor address family group, all neighbors using the group inherit the configuration. Values of commands configured specifically for a neighbor override inherited values.
Examples
The following example shows how to configure the router to send extended community attributes to neighbor 172.20.1.1 for IP Version 4 (IPv4) multicast routes:
RP/0/RP0/CPU0:router(config)# router bgp 140RP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 multicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# send-extended-community-ebgpThe following example shows how to disable the delivery of extended community attributes to neighbor 172.20.1.1, preventing this feature from being automatically inherited from address family group group1:
RP/0/RP0/CPU0:router(config)# router bgp 140RP/0/RP0/CPU0:router(config-bgp)# af-group group1 address-family ipv4 multicastRP/0/RP0/CPU0:router(config-bgp-afgrp)# send-extended-community-ebgpRP/0/RP0/CPU0:router(config-bgp-afgrp)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 172.20.1.1RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 multicastRP/0/RP0/CPU0:router(config-bgp-nbr-af)# use af-group group1RP/0/RP0/CPU0:router(config-bgp-nbr-af)# send-extended-community-ebgp disableRelated Commands
session-group
To create a session group and enter session group configuration mode, use the session-group command in router configuration mode. To remove a session group and delete all configurations associated with it, use the no form of this command.
session-group name
no session-group name
Syntax Description
Defaults
No session groups are created.
Command Modes
Router configuration
Command History
Release 2.0
This command was introduced on the Cisco CRS-1.
Release 3.0
No modification.
Release 3.2
This command was supported on the Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
Use the session-group command to create a session group from which neighbors can inherit configuration that is address family-independent. That is, session groups cannot have address family-specific configuration. This command enters the session group configuration mode in which configuration for a session group is entered.
Many commands can be configured in both session group configuration mode and neighbor configuration mode.
Use of session groups saves time and reduces the router configuration size. Because the configuration of a session group can be inherited by any number of neighbors, use of the group can eliminate the need to copy long or complex configurations on each of a large number of neighbors. A neighbor can inherit all configuration from a session group simply by configuring the use command. Specific inherited session group configuration commands can be overridden for a specific neighbor by explicitly configuring the command for the specific neighbor.
The no form of this command causes all of the configuration for the session group to be removed. You cannot use the no form of this command if removing the group would leave one or more neighbors without a configured remote autonomous system number.
Examples
The following example shows a session group called group1 that is used by two neighbors, 10.0.0.1 and 10.0.0.2. Because group1 is a session group, it contains only address family-independent configuration. And because group1 is used by neighbors 10.0.0.1 and 10.0.0.2, they inherit the configuration of the group.
RP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# session-group group1RP/0/RP0/CPU0:router(config-bgp-sngrp)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-sngrp)# advertisement-interval 2RP/0/RP0/CPU0:router(config-bgp-sngrp)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.0.1RP/0/RP0/CPU0:router(config-bgp-nbr)# use session-group group1RP/0/RP0/CPU0:router(config-bgp-nbr)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.0.2RP/0/RP0/CPU0:router(config-bgp-nbr)# use session-group group1The following example shows a session group called group1 used by two neighbors, 10.0.0.1 and 10.0.0.2. Because group1 is a session group, it contains only address family-independent configuration. And because group1 is used by neighbors 10.0.0.1 and 10.0.0.2, they inherit the configuration of the group. However, the password password1 configuration from group1 is overridden for neighbor 10.0.0.2, using the password-disable command in the neighbor 10.0.0.2 configuration submode.
RP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# session-group group1RP/0/RP0/CPU0:router(config-bgp-sngrp)# remote-as 1RP/0/RP0/CPU0:router(config-bgp-sngrp)# advertisement-interval 2RP/0/RP0/CPU0:router(config-bgp-sngrp)# password password1RP/0/RP0/CPU0:router(config-bgp-sngrp)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.0.1RP/0/RP0/CPU0:router(config-bgp-nbr)# use session-group group1RP/0/RP0/CPU0:router(config-bgp-nbr)# exitRP/0/RP0/CPU0:router(config-bgp)# neighbor 10.0.0.2RP/0/RP0/CPU0:router(config-bgp-nbr)# use session-group group1RP/0/RP0/CPU0:router(config-bgp-nbr)# password-disablesession-open-mode
To establish a Border Gateway Protocol (BGP) session with a specific TCP open mode, use the session-open-mode command in the appropriate configuration mode. To end the session, use the no form of this command.
session-open-mode {active-only | both | passive-only}
no session-open-mode
Syntax Description
Defaults
Session-open-mode is not inherited from the parent.
Command Modes
Neighbor configuration
Neighbor group configuration
Session group configurationCommand History
Release 3.2
This command was introduced on the Cisco CRS-1 and Cisco XR 12000 Series Router.
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes the proper task IDs. For detailed information about user groups and task IDs, see the Configuring AAA Services on Cisco IOS XR Software module of the Cisco IOS XR System Security Configuration Guide.
BGP, by default, tries to initiate an active TCP connection whenever a new neighbor is configured. A remote neighbor may also initiate the TCP connection before the local BGP can initiate the connection. This initiation of a TCP connection by a remote neighbor is considered a passive-open request and it is accepted by the local BGP. This default behavior can be modified using the session-open-mode command.
Use the session-open-mode command when it may be necessary to pre-configure a neighbor that does not exist. Ensure that BGP does not spend any time actively trying to set up a TCP session with the neighbor. A BGP session does not come up between two neighbors, both of which configure the same non default value (active-only or passive-only keyword) for this command.
Examples
The following example shows how to enable a BGP session on router bgp 1:
RP/0/RP0/CPU0:router(config)# router bgp 1RP/0/RP0/CPU0:router(config-bgp)# neighbor 45.67.89.01RP/0/RP0/CPU0:router(config-bgp-nbr)# session-open-modeshow bgp
To display entries in the Border Gateway Protocol (BGP) routing table, use the show bgp command in EXEC mode.
show bgp [ipv4 {unicast | multicast | all} | ipv6 {unicast | all} | all {
