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Cisco IOS IP Routing Protocols Command Reference
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Introduction
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BGP Commands: A through B
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BGP Commands: C through I
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BGP Commands: M through neighbor soo
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BGP Commands: neighbor timers through show bgp nsap summary
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BGP Commands: show ip bgp through T
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EIGRP Commands: A through I
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EIGRP Commands: M through V
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Integrated IS-IS Commands: A through I
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Integrated IS-IS Commands: L through V
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On-Demand Routing Commands
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OSPF Commands: A through ip ospf demand-circuit
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OSPF Commands: ip ospf flood-reduction through R
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OSPF Commands: show ip ospf through T
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IP Routing Protocol-Independent Commands: A through R
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IP Routing Protocol-Independent Commands: S through T
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RIP Commands
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Table Of Contents
bgp bestpath cost-community ignore
bgp bestpath med missing-as-worst
bgp client-to-client reflection
BGP Commands
address-family ipv4 (BGP)
To enter address family or router scope address family configuration mode to configure a routing session using standard IP Version 4 address prefixes, use the address-family ipv4 command in router configuration or router scope configuration mode. To exit address family configuration mode and remove the IPv4 address family configuration from the running configuration, use the no form of this command.
Syntax Available Under Router Configuration Mode
address-family ipv4 [mdt | multicast | tunnel | unicast [vrf vrf-name] | vrf vrf-name]
no address-family ipv4 [mdt | multicast | tunnel | unicast [vrf vrf-name] | vrf vrf-name]
Syntax Available Under Router Scope Configuration Mode
address-family ipv4 [mdt | multicast | unicast]
no address-family ipv4 [mdt | multicast | unicast]
Syntax Description
Command Default
IP Version 4 address prefixes are not enabled.
Command Modes
Router configuration (config-router)
Router scope configuration (config-router-scope)Command History
Usage Guidelines
The address-family ipv4 command replaces the match nlri and set nlri commands. The address-family ipv4 command places the router in address family configuration mode (prompt: config-router-af), from which you can configure routing sessions that use standard IP Version 4 address prefixes. To leave address family configuration mode and return to router configuration mode, type exit.
Note
Routing information for address family IPv4 is advertised by default for each BGP routing session configured with the neighbor remote-as command unless you enter the no bgp default ipv4-unicast command before configuring the neighbor remote-as command.
The tunnel keyword is used to enable the tunnel subaddress family identifier (SAFI) under the IPv4 address family identifier. This SAFI is used to advertise the tunnel endpoints and the SAFI-specific attributes (which contain the tunnel type and tunnel capabilities). Redistribution of tunnel endpoints into the BGP IPv4 tunnel SAFI table occurs automatically when the tunnel address family is configured. However, peers need to be activated under the tunnel address family before the sessions can exchange tunnel information.
The mdt keyword is used to enable the MDT SAFI under the IPv4 address family identifier. This SAFI is used to advertise tunnel endpoints for inter-AS multicast VPN peering sessions.
In Cisco IOS Release 12.2(33)SRB and later releases, the ability to use address family configuration under the router scope configuration mode was introduced. The scope hierarchy can be defined for BGP routing sessions and is required to support Multi-Topology Routing (MTR). To enter the router scope configuration mode, use the scope command, which can apply globally or for a specific VRF. When using the scope for a specific VRF, only the unicast keyword is available.
Examples
The following example places the router in address family configuration mode for the IP Version 4 address family:
Router(config)# router bgp 50000Router(config-router)# address-family ipv4Router(config-router-af)#Multicast Example
The following example places the router in address family configuration mode and specifies only multicast address prefixes for the IP Version 4 address family:
Router(config)# router bgp 50000Router(config-router)# address-family ipv4 multicastRouter(config-router-af)#Unicast Example
The following example places the router in address family configuration mode and specifies unicast address prefixes for the IP Version 4 address family:
Router(config)# router bgp 50000Router(config-router)# address-family ipv4 unicastRouter(config-router-af)#VRF Example
The following example places the router in address family configuration mode and specifies cisco as the name of the VRF instance to associate with subsequent IP Version 4 address family configuration mode commands:
Router(config)# router bgp 50000Router(config-router)# address-family ipv4 vrf ciscoRouter(config-router-af)#
Note
Tunnel Example
The following example places the router in tunnel address family configuration mode:
Router(config)# router bgp 100Router(config-router)# address-family ipv4 tunnelRouter(config-router-af)#MDT Example
The following example shows how to configure a router to support an IPv4 MDT address-family session:
Router(config)# router bgp 45000Router(config-router)# address-family ipv4 mdtRouter(config-router-af)#Router Scope Configuration Mode Example
The following example shows how to configure the IPv4 address family under router scope configuration mode. In this example, the scope hierarchy is enabled globally. The router enters router scope address family configuration mode, and only multicast address prefixes for the IP Version 4 address family are specified:
Router(config)# router bgp 50000Router(config-router)# scope globalRouter(config-router-scope)# address-family ipv4 multicastRouter(config-router-scope-af)#Related Commands
address-family l2vpn
To enter address family configuration mode to configure a routing session using Layer 2 Virtual Private Network (L2VPN) endpoint provisioning address information, use the address-family l2vpn command in router configuration mode. To remove the L2VPN address family configuration from the running configuration, use the no form of this command.
address-family l2vpn [vpls]
no address-family l2vpn [vpls]
Syntax Description
vpls
(Optional) Specifies L2VPN Virtual Private LAN Service (VPLS) endpoint provisioning address information.
Command Default
No L2VPN endpoint provisioning support is enabled.
Command Modes
Router configuration
Command History
Usage Guidelines
The address-family l2vpn command places the router in address family configuration mode (prompt: config-router-af), from which you can configure routing sessions that support L2VPN endpoint provisioning.
BGP support for the L2VPN address family introduces a BGP-based autodiscovery mechanism to distribute L2VPN endpoint provisioning information. BGP uses a separate L2VPN routing information base (RIB) to store endpoint provisioning information, which is updated each time any Layer 2 (L2) virtual forwarding instance (VFI) is configured. Prefix and path information is stored in the L2VPN database, allowing BGP to make best-path decisions. When BGP distributes the endpoint provisioning information in an update message to all its BGP neighbors, the endpoint information is used to set up a pseudowire mesh to support L2VPN-based services.
The BGP autodiscovery mechanism facilitates the setting up of L2VPN services, which are an integral part of the Cisco IOS Virtual Private LAN Service (VPLS) feature. VPLS enables flexibility in deploying services by connecting geographically dispersed sites as a large LAN over high-speed Ethernet in a robust and scalable IP MPLS network.
Note
Examples
In this example, two provider edge (PE) routers are configured with VPLS endpoint provisioning information that includes L2 VFI, VPN, and VPLS IDs. BGP neighbors are configured and activated under L2VPN address family to ensure that the VPLS endpoint provisioning information is saved to a separate L2VPN RIB and then distributed to other BGP peers in BGP update messages. When the endpoint information is received by the BGP peers, a pseudowire mesh is set up to support L2VPN-based services.
Router A
enableconfigure terminall2 vfi customerA autodiscoveryvpn id 100vpls-id 45000:100exitl2 vfi customerB autodiscoveryvpn id 200vpls-id 45000:200exitrouter bgp 45000no bgp default ipv4-unicastbgp log-neighbor-changesneighbor 172.16.1.2 remote-as 45000neighbor 172.21.1.2 remote-as 45000address-family l2vpn vplsneighbor 172.16.1.2 activateneighbor 172.16.1.2 send-community extendedneighbor 172.21.1.2 activateneighbor 172.21.1.2 send-community extendedendRouter B
enableconfigure terminall2 vfi customerA autodiscoveryvpn id 100vpls-id 45000:100exitl2 vfi customerB autodiscoveryvpn id 200vpls-id 45000:200exitrouter bgp 45000no bgp default ipv4-unicastbgp log-neighbor-changesneighbor 172.16.1.1 remote-as 45000neighbor 172.22.1.1 remote-as 45000address-family l2vpn vplsneighbor 172.16.1.1 activateneighbor 172.16.1.1 send-community extendedneighbor 172.22.1.1 activateneighbor 172.22.1.1 send-community extendedendRelated Commands
neighbor activate
Enables the exchange of information with a BGP neighboring router.
show ip bgp l2vpn
Displays L2VPN address family information.
address-family nsap
To enter address family configuration mode to configure Connectionless Network Service (CLNS)-specific parameters for Border Gateway Protocol (BGP) routing sessions, use the address-family nsap command in router configuration mode. To exit address family configuration mode and remove the CLNS address family configuration from the running configuration, use the no form of this command.
address-family nsap [unicast]
no address-family nsap [unicast]
Syntax Description
Command Default
NSAP prefix support is not enabled.
Note
Command Modes
Router configuration
Command History
12.2(8)T
This command was introduced.
12.2(33)SRB
This command was integrated into Cisco IOS Release 12.2(33)SRB.
Usage Guidelines
The address-family nsap command enters address family configuration mode (prompt: config-router-af)#, from which you can configure routing sessions that use standard NSAP address prefixes; you must enter NSAP address family configuration mode to configure BGP for CLNS prefixes.
To leave address family configuration mode and return to router configuration mode without removing the existing configuration, enter the exit-address-family command.
Examples
The following example enters NSAP address family configuration mode under BGP:
Router(config)# router bgp 50000Router(config-router)# address-family nsapRouter(config-router-af)#Related Commands
address-family vpnv4
To enter address family configuration mode to configure a routing session using Virtual Private Network (VPN) Version 4 address prefixes, use the address-family vpnv4 command in router configuration mode. To exit address family configuration mode and remove the VPNv4 address family configuration from the running configuration, use the no form of this command.
address-family vpnv4 [unicast]
no address-family vpnv4 [unicast]
Syntax Description
Defaults
Unicast prefix support is enabled by default when this command is entered without any optional keywords.
Note
Command Modes
Router configuration
Command History
12.0(5)T
This command was introduced.'
12.2(33)SRA
This command was integrated into Cisco IOS Release 12.2(33)SRA.
Usage Guidelines
The address-family vpnv4 command replaces the match nlri and set nlri commands.
The address-family vpnv4 command places the router in address family configuration mode (prompt: config-router-af)#, from which you can configure routing sessions that use VPN Version 4 address prefixes.
To leave address family configuration mode and return to router configuration mode without removing the existing configuration, enter the exit-address-family command.
Examples
The following example places the router in address family configuration mode for the VPN Version 4 address family:
Router(config)# router bgp 50000Router(config-router)# address-family vpnv4Router(config-router-af)#The following example places the router in address family configuration mode for the unicast VPN Version 4 address family:
Router(config)# router bgp 50000Router(config-router)# address-family vpnv4 unicastRouter(config-router-af)#Related Commands
aggregate-address
To create an aggregate entry in a Border Gateway Protocol (BGP) database, use the aggregate-address command in address family or router configuration mode. To disable this function, use the no form of this command.
aggregate-address address mask [as-set] [summary-only] [suppress-map map-name] [advertise-map map-name] [attribute-map map-name]
no aggregate-address address mask [as-set] [summary-only] [suppress-map map-name] [advertise-map map-name] [attribute-map map-name]
Syntax Description
Command Default
The atomic aggregate attribute is set automatically when an aggregate route is created with this command unless the as-set keyword is specified.
Command Modes
Address family configuration
Router configurationCommand History
Usage Guidelines
You can implement aggregate routing in BGP and mBGP either by redistributing an aggregate route into BGP or mBGP, or by using the conditional aggregate routing feature.
Using the aggregate-address command with no keywords will create an aggregate entry in the BGP or mBGP routing table if any more-specific BGP or mBGP routes are available that fall within the specified range. (A longer prefix which matches the aggregate must exist in the RIB.) The aggregate route will be advertised as coming from your autonomous system and will have 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.)
Using the as-set keyword creates an aggregate entry using the same rules that the command follows without this keyword, but the path advertised for this route will be an AS_SET consisting of all elements 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.
Using the summary-only keyword not only creates the aggregate route (for example, 192.*.*.*) but also suppresses advertisements of more-specific routes to all neighbors. If you want to suppress only advertisements to certain neighbors, you may use the neighbor distribute-list command, with caution. If a more-specific route leaks out, all BGP or mBGP routers will prefer that route over the less-specific aggregate you are generating (using longest-match routing).
Using the suppress-map keyword creates the aggregate route but suppresses advertisement of specified routes. You can use the match clauses of route maps to selectively suppress some more-specific routes of the aggregate and leave others unsuppressed. IP access lists and autonomous system path access lists match clauses are supported.
Using the advertise-map keyword selects specific routes that will be used to build different components of the aggregate route, such as AS_SET or community. This form of the aggregate-address command is useful when the components of an aggregate are in separate autonomous systems and you want to create an aggregate with AS_SET, and advertise it back to some of the same autonomous systems. You must remember to omit the specific autonomous system numbers from the AS_SET to prevent the aggregate from being dropped by the BGP loop detection mechanism at the receiving router. IP access lists and autonomous system path access lists match clauses are supported.
Using the attribute-map keyword allows attributes of the aggregate route to be changed. This form of the aggregate-address command is useful when one of the routes forming the AS_SET is configured with an attribute such as the community no-export attribute, which would prevent the aggregate route from being exported. An attribute map route map can be created to change the aggregate attributes.
Examples
AS-Set Example
In the following example, an aggregate BGP address is created in router configuration mode. The path advertised for this route will be an AS_SET consisting of all elements contained in all paths that are being summarized.
Router(config)# router bgp 50000Router(config-router)# aggregate-address 10.0.0.0 255.0.0.0 as-setSummary-Only Example
In the following example, an aggregate BGP address is created in address family configuration mode and applied to the multicast database (SAFI) under the IP Version 4 address family. Because the summary-only keyword is configured, more-specific routes are filtered from updates.
Router(config)# router bgp 50000Router(config-router)# address-family ipv4 multicastRouter(config-router-af)# aggregate-address 10.0.0.0 255.0.0.0 summary-onlyConditional Aggregation Example
In the following example, a route map called MAP-ONE is created to match on an as-path access list. The path advertised for this route will be an AS_SET consisting of elements contained in paths that are matched in the route map.
Router(config)# ip as-path access-list 1 deny ^1234_Router(config)# ip as-path access-list 1 permit .*Router(config)# !Router(config)# route-map MAP-ONERouter(config-route-map)# match ip as-path 1Router(config-route-map)# exitRouter(config)# router bgp 50000Router(config-router)# address-family ipv4Router(config-router-af)# aggregate-address 10.0.0.0 255.0.0.0 as-set advertise-map MAP-ONERouter(config-router-af)# endRelated Commands
auto-summary (BGP)
To configure automatic summarization of subnet routes into network-level routes, use the auto-summary command in address family or router configuration mode. To disable automatic summarization and send subprefix routing information across classful network boundaries, use the no form of this command.
auto-summary
no auto-summary
Syntax Description
This command has no arguments or keywords.
Command Default
Automatic summarization is disabled by default (the software sends subprefix routing information across classful network boundaries).
BGP automatically summarizes to classful network boundaries when this command is enabled.
Command Modes
Address family configuration
Router configurationCommand History
Usage Guidelines
Route summarization is used to reduce the amount of routing information in routing tables.
By default, BGP does not accept subnets redistributed from an Interior Gateway Protocol (IGP). To allow Cisco IOS Software to create summary subprefixes to the classful network boundary when crossing classful network boundaries, use the auto-summary command. To advertise and carry subnet routes in BGP when automatic summarization is enabled, use an explicit network command statement to advertise the subnet.
Examples
In the following example, automatic summarization is enabled for IPv4 address family prefixes:
Router(config)# router bgp 50000Router(config-router)# address-family ipv4 unicastRouter(config-router-af)# auto-summaryRelated Commands
bgp always-compare-med
To enable the comparison of the Multi Exit Discriminator (MED) for paths from neighbors in different autonomous systems, use the bgp always-compare-med command in router configuration mode. To disallow the comparison, use the no form of this command.
bgp always-compare-med
no bgp always-compare-med
Syntax Description
This command has no arguments or keywords.
Command Default
Cisco IOS software does not compare the MED for paths from neighbors in different autonomous systems if this command is not enabled or if the no form of this command is entered. The MED is compared only if the autonomous system path for the compared routes is identical.
Command Modes
Router configuration
Command History
Usage Guidelines
The MED, as stated in RFC 1771, is an optional nontransitive attribute that is a four octet non-negative integer. The value of this attribute may be used by the BGP best path selection process to discriminate among multiple exit points to a neighboring autonomous system.
The MED is one of the parameters that is considered when selecting the best path among many alternative paths. The path with a lower MED is preferred over a path with a higher MED. During the best-path selection process, MED comparison is done only among paths from the same autonomous system. The bgp always-compare-med command is used to change this behavior by enforcing MED comparison between all paths, regardless of the autonomous system from which the paths are received.
The bgp deterministic-med command can be configured to enforce deterministic comparison of the MED value between all paths received from within the same autonomous system.
Examples
In the following example, the local BGP routing process is configured to compare the MED from alternative paths, regardless of the autonomous system from which the paths are received:
Router(config)# router bgp 500000Router(config-router)# bgp always-compare-medRelated Commands
bgp deterministic-med
Enforces deterministic comparison of the MED value between all paths received from within the same autonomous system
bgp bestpath as-path ignore
To configure Border Gateway Protocol (BGP) to not consider the autonomous system (AS) path during best path route selection, use the bgp bestpath as-path ignore command in router configuration mode. To restore default behavior and configure BGP to consider the AS-path during route selection, 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.
Command Default
The AS-path is considered during BGP best path selection.
Command Modes
Router configuration
Command History
Examples
In the following example, the BGP routing process is configured to not consider the AS-path during best path selection:
Router(config)# router bgp 40000Router(config-router)# bgp bestpath as-path ignoreRelated Commands
show ip bgp ipv4
Displays information about the TCP and BGP connections to neighbors.
bgp bestpath compare-routerid
To configure a Border Gateway Protocol (BGP) routing process to compare identical routes received from different external peers during the best path selection process and to select the route with the lowest router ID as the best path, use the bgp bestpath compare-routerid command in router configuration mode. To return the BGP routing process to the default operation, use the no form of this command.
bgp bestpath compare-routerid
no bgp bestpath compare-routerid
The behavior of this command is disabled by default; BGP selects the route that was received first when two routes with identical attributes are received.
Command HistoryRouter configuration
Usage Guidelines
The bgp bestpath compare-routerid command is used to configure a BGP routing process to use the router ID as the tie breaker for best path selection when two identical routes are received from two different peers (all the attributes are the same except for the router ID). When this command is enabled, the lowest router ID will be selected as the best path when all other attributes are equal.
In the following example, the BGP routing process is configured to compare and use the router ID as a tie breaker for best path selection when identical paths are received from different peers:
Router(config)# router bgp 50000Router(config-router)# bgp bestpath compare-routeridRelated Commands
bgp bestpath cost-community ignore
To configure a router that is running the Border Gateway Protocol (BGP) to not evaluate the cost community attribute during the best path selection process, use the bgp bestpath cost-community ignore command in router configuration mode. To return the router to default operation, use the no form of this command.
bgp bestpath cost-community ignore
no bgp bestpath cost-community ignore
Syntax Description
This command has no keywords or arguments.
Command Default
The behavior of this command is enabled by default until the cost community attribute is manually configured.
Command Modes
Address family configuration
Router configurationCommand History
Usage Guidelines
The bgp bestpath cost-community ignore command is used to disable the evaluation of the cost community attribute to help isolate problems and troubleshoot issues that relate to BGP path selection. This command can also be used to delay the activation of cost community attribute evaluation so that cost community filtering can be deployed in a large network at the same time.
Examples
The following example shows how to configure a router to not evaluate the cost community attribute during the best path selection process:
router bgp 50000address-family ipv4 unicastbgp bestpath cost-community ignoreRelated Commands
set extcommunity cost
Creates a set clause to apply the cost community attribute to routes that pass through a route map.
show ip bgp
Displays entries in the BGP routing table.
bgp bestpath med confed
To configure a Border Gateway Protocol (BGP) routing process to compare the Multi Exit Discriminator (MED) between paths learned from confederation peers, use the bgp bestpath med confed command in router configuration mode. To disable MED comparison of paths received from confederation peers, use the no form of this command.
bgp bestpath med confed [missing-as-worst]
no bgp bestpath med confed [missing-as-worst]
Syntax Description
missing-as-worst
(Optional) Assigns the value of infinity to received routes that do not carry the MED attribute, making these routes the least desirable.
Defaults
Cisco IOS software does not consider the MED attribute when choosing among paths learned from confederation peers if this command is not enabled or if the no form of this command is entered.
Command Modes
Router configuration
Command History
Usage Guidelines
The MED comparison between confederation peers occurs only if no external autonomous systems are in the path (an external autonomous system is an autonomous system that is not within the confederation). If an external autonomous system in the path, then the external MED is passed transparently through the confederation, and the comparison is does not occur.
For example, assume that autonomous system 65000, 65001, 65002, and 65004 are part of the confederation; autonomous system 1 is not; and we are comparing route A with four paths. If the bgp bestpath med confed command is enabled, path 1 would be chosen. The fourth path has a lower MED, but it is not involved in the MED comparison because there is an external autonomous system in this path. The following list displays the MED for each autonomous system.
path = 65000 65004, med = 2
path = 65001 65004, med = 3
path = 65002 65004, med = 4
path = 65003 1, med = 1
Examples
In the following example, the BGP routing process is configured to compare MED values for paths learned from confederation peers:
Router(config)# router bgp 50000Router(config-router)# bgp bestpath med confedRelated Commands
show ip bgp
Displays entries in the BGP routing table.
show ip bgp ipv4
Displays information about the TCP and BGP connections to neighbors.
bgp bestpath med missing-as-worst
To configure a Border Gateway Protocol (BGP) routing process to assign a value of infinity to routes that are missing the Multi Exit Discriminator (MED) attribute (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 return the router to the default behavior (assign a value of 0 to the missing MED), 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
Cisco IOS software assigns a value of 0 to routes the are missing the MED attribute, causing the route with the missing MED attribute to be considered the best path.
Command Modes
Router configuration
Command History
Examples
In the following example, the BGP router process is configured to consider a route with a missing MED attribute as having a value of infinity (4294967294), making this path the least desirable path:
Router(config)# router bgp 50000Router(config-router)# bgp bestpath med missing-as-worstRelated Commands
show ip bgp
Displays entries in the BGP routing table.
show ip bgp ipv4
Displays information about the TCP and BGP connections to neighbors.
bgp client-to-client reflection
To enable or restore route reflection from a BGP route reflector to clients, use the bgp client-to-client reflection command in router configuration mode. To disable client-to-client route reflection, use the no form of this command.
bgp client-to-client reflection
no bgp client-to-client reflection
Syntax Description
This command has no arguments or keywords.
Defaults
Client-to-client route reflection is enabled by default; when a route reflector is configured, the route reflector reflects routes from a client to other clients.
Command Modes
Router configuration
Command History
Usage Guidelines
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. In this case, use the no bgp client-to-client reflection command to disable client-to-client reflection.
Examples
In the following example, the local router is a route reflector, and the three neighbors are fully meshed. Because the neighbors are fully meshed, client-to-client reflection is disabled with the no bgp client-to-client reflection command.
Router(config)# router bgp 50000Router(config-router)# neighbor 10.24.95.22 route-reflector-clientRouter(config-router)# neighbor 10.24.95.23 route-reflector-clientRouter(config-router)# neighbor 10.24.95.24 route-reflector-clientRouter(config-router)# no bgp client-to-client reflectionRouter(config-router)# endRelated Commands
bgp cluster-id
To set the cluster ID on a route reflector in a route reflector cluster, 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 cluster-id
Syntax Description
cluster-id
Cluster ID of this router acting as a route reflector; maximum of 4 bytes. The ID can be specified in dotted or decimal format.
Defaults
The local router ID of the route reflector is used as the cluster ID when no ID is specified or when the no form of this command is entered.
Command Modes
Router configuration
Command History
Usage Guidelines
Together, a route reflector and its clients form a cluster. When a single route reflector is deployed in a cluster, the cluster is identified by the router ID of the route reflector.
The bgp cluster-id command is used to assign a cluster ID to a route reflector when the cluster has one or more route reflectors. Multiple route reflectors are deployed in a cluster to increase redundancy and avoid a single point of failure. When multiple route reflectors are configured in a cluster, the same cluster ID is assigned to all route reflectors. This allows all route reflectors in the cluster to recognize updates from peers in the same cluster and reduces the number of updates that need to be stored in BGP routing tables.
Note
Examples
In the following example, the local router is one of the route reflectors serving the cluster. It is configured with the cluster ID to identify the cluster.
Router(config)# router bgp 50000Router(config-router)# neighbor 192.168.70.24 route-reflector-clientRouter(config-router)# bgp cluster-id 10.0.1.2Related Commands
bgp confederation identifier
To specify a 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 as-number
no bgp confederation identifier as-number
Syntax Description
as-number
Autonomous system number to be configured to internally include multiple autonomous systems.
Defaults
No default behavior or values
Command Modes
Router configuration
Command History
