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IP Routing: BGP Configuration Guide, Cisco IOS XE Release 3S (Cisco ASR 920 Series)

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Book Title

IP Routing: BGP Configuration Guide, Cisco IOS XE Release 3S (Cisco ASR 920 Series)

Chapter Title

BGP NSR Support for iBGP Peers

Results

Updated:
May 12, 2022

Chapter: BGP NSR Support for iBGP Peers

BGP NSR Support for iBGP Peers

BGP NSR provides BGP nonstop routing (NSR) and nonstop forwarding (NSF) in the event of a switchover from an Active RP to the Standby RP. The BGP NSR Support for iBGP Peers feature provides NSR support for iBGP peers configured under the IPv4 unicast or IPv4 + label address family.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Restrictions on BGP NSR Support for iBGP Peers

  • This feature applies to iBGP peers configured under IPv4 unicast or IPv4 + label address families.

  • When you configure BGP with graceful restart and remove the BGP configuration using no router bgp command, the graceful restart timer starts. As a result, the stale entry is present in the BGP routing table and it is only removed after the BGP graceful restart timer is over.

Information About BGP NSR Support for iBGP Peers

Benefit of BGP NSR Support for iBGP Peers

Nonstop routing is beneficial for iBGP peers because it reduces the likelihood of dropped packets during switchover from the Active RP to the Standby RP. Switchover occurs when the Active RP fails for some reason, and the Standby RP takes control of Active RP operations.

How to Configure BGP NSR Support for iBGP Peers

Making an iBGP Peer NSR-Capable for the IPv4 Address Family

Procedure

  Command or Action Purpose
Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

router bgp autonomous-system-number

Example:


Device(config)# router bgp 4000

Enters router configuration mode for the specified routing process.

Step 4

address-family ipv4 [unicast | vrf vrf-name ]

Example:


Device(config-router)# address-family ipv4 unicast

Specifies the IPv4 address family and enters address family configuration mode.

  • The unicast keyword specifies the IPv4 unicast address family.

  • The vrf keyword and vrf-name argument specify the name of the virtual routing and forwarding (VRF) instance to associate with subsequent IPv4 address family configuration mode commands.

Step 5

neighbor ip-address remote-as as-number

Example:


Device(config-router-af)# neighbor 192.168.1.1 remote-as 4000

Specifies the autonomous system of the neighbor.

Step 6

neighbor ip-address activate

Example:


Device(config-router-af)# neighbor 192.168.1.1 activate

Activates the specified peer.

Step 7

neighbor ip-address ha-mode sso

Example:


Device(config-router-af)# neighbor 192.168.1.1 ha-mode sso

Configures a BGP neighbor to support BGP NSR with stateful switchover (SSO).

Step 8

end

Example:


Device(config-router-af)# end

Exits address family configuration mode and returns to privileged EXEC mode.

Making an iBGP Peer NSR-Capable for the VPNv4 Address Family

Procedure

  Command or Action Purpose
Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

router bgp autonomous-system-number

Example:


Device(config)# router bgp 4000

Enters router configuration mode for the specified routing process.

Step 4

neighbor ip-address remote-as as-number

Example:


Device(config-router)# neighbor 192.168.1.1 remote-as 4000

Specifies the autonomous system of the neighbor.

Step 5

neighbor ip-address ha-mode sso

Example:


Device(config-router)# neighbor 192.168.1.1 ha-mode sso

Configures a BGP neighbor to support BGP NSR with stateful switchover (SSO).

Step 6

address-family vpnv4 [unicast ]

Example:


Device(config-router)# address-family VPNv4 unicast

Specifies the VPNv4 address family and enters address family configuration mode.

Step 7

neighbor ip-address activate

Example:


Device(config-router-af)# neighbor 192.168.1.1 activate

Activates the specified peer.

Step 8

end

Example:


Device(config-router-af)# end

Exits address family configuration mode and returns to privileged EXEC mode.

Making an iBGP Peer NSR Capable at the Router Level

Procedure

  Command or Action Purpose
Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

router bgp autonomous-system-number

Example:


Device(config)# router bgp 4000

Enters router configuration mode for the specified routing process.

Step 4

neighbor ip-address remote-as as-number

Example:


Device(config-router)# neighbor 192.168.1.1 remote-as 4000

Specifies the autonomous system of the neighbor.

Step 5

neighbor ip-address activate

Example:


Device(config-router)# neighbor 192.168.1.1 activate

Activates the specified neighbor.

Step 6

neighbor ip-address ha-mode sso

Example:


Device(config-router)# neighbor 192.168.1.1 ha-mode sso

Configures the specified peer to be NSR capable in all of the NSR-supported address families under which that peer has been activated.

Step 7

end

Example:


Device(config-router)# end

Exits configuration mode and returns to privileged EXEC mode.

Step 8

show ip bgp sso summary

Example:

Device# show ip bgp sso summary

(Optional) Displays information about stateful switchover (sso) and whether a peer has NSR enabled or disabled.

Configuration Examples for BGP NSR Support for an iBGP Peer

Example: Configuring an iBGP Peer To Be NSR Capable

Configuring an iBGP Peer to Be NSR Capable at the Address Family Level


router bgp 4000
 address-family ipv4 unicast
 neighbor 192.168.1.1 remote-as 4000
 neighbor 192.168.1.1 activate
 neighbor 192.168.1.1 ha-mode sso

Configuring an iBGP Peer to Be NSR Capable at the Router Level 


router bgp 4000
 neighbor 192.168.1.1 remote-as 4000
 neighbor 192.168.1.1 activate 
 neighbor 192.168.1.1 ha-mode sso

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Command List, All Releases

BGP commands

Cisco IOS IP Routing: BGP Command Reference

BFD commands

Cisco IOS IP Routing: Protocol Independent Command Reference

Configuring BFD support for another routing protocol

IP Routing: BFD Configuration Guide

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