graceful-restart (BGP)

Enables the BGP graceful restart capability.

Syntax

graceful-restart [ purge-time seconds | restart-time seconds | stale-routes-time seconds ]

no graceful-restart

Command Default

Disabled.

Parameters

purge-time: Specifies the maximum period of time, in seconds, for which a restarting device maintains stale routes in the BGP routing table before purging them. The default value is 600 seconds. The configurable range of values is from 1 to 3600 seconds.
restart-time: Specifies the restart-time, in seconds, advertised to graceful restart-capable neighbors. The default value is 120 seconds. The configurable range of values is from 1 to 3600 seconds.
stale-routes-time: Specifies the maximum period of time, in seconds, that a helper device will wait for an End-of-RIB (EOR) message from a peer. All stale paths are deleted when this time period expires. The default value is 360 seconds. The configurable range of values is from 1 to 3600 seconds.

Modes

BGP address-family IPv4 unicast configuration mode

BGP address-family IPv6 unicast configuration mode

BGP address-family IPv4 unicast VRF configuration mode

BGP address-family IPv6 unicast VRF configuration mode

BGP address-family L2VPN EVPN configuration mode

Usage Guidelines

Use this command under a BGP address-family configuration mode to enable or disable the graceful-restart capability for all BGP neighbors in the address family. When this command is enabled, graceful-restart capability is negotiated with neighbors in the BGP OPEN message when a session is established. If the neighbor advertises support for graceful restart, that function is activated for that neighbor session. Otherwise, graceful restart is not activated for that session, even though it is enabled locally. If the neighbor has not sent graceful-restart parameters, the restarting device will not wait for the neighbor to start route calculation, but graceful restart will be enabled.

If the graceful-restart capability is enabled after a BGP session has been established, the neighbor session must be cleared for graceful restart to take effect.

The purge-time parameter is applicable for both restarting and helper devices. The timer starts when a BGP connection is closed. The timer ends when an EOR is received from all nodes, downloaded into BGP and an EOR sent to all neighbors. The configured purge-time timer value is effective only on the configured node.

The restart-time parameter is applicable only for helper devices. The timer starts at the time the BGP connection is closed by the remote peer and ends when the Peer connection is established. The configured restart-time timer value is effective only on the peer node, and not in the configured node. During negotiation time, the timer value is exchanged.

The stale-routes-time parameter is applicable only for helper devices. The timer starts when the peer connection is established after the HA-failover. The timer ends at the time an EOR is received from the peer. The configured stale-time timer value is effective only on the configured node.

For non-default VRF instances, graceful restart timers are inherited from the default VRF. The purge-time, restart-time, and stale-routes-time parameters are not available in BGP address-family IPv4 unicast VRF configuration mode and BGP address-family IPv6 unicast VRF configuration mode.

Use the clear ip bgp neighbor command with the all parameter for the changes to the graceful-restart parameters to take effect immediately.

The no form of the command disables the BGP graceful-restart capability globally for all BGP neighbors in the address family.

Examples

The following example enables the BGP graceful restart capability.

device# configure terminal
device(config)# router bgp
device(config-bgp-router)# local-as 1
device(config-bgp-router)# neighbor 1.1.1.1 remote-as 2
device(config-bgp-router)# address-family ipv4 unicast
device(config-bgp-ipv4u)# graceful-restart

The following example sets the purge time to 240 seconds.

device# configure terminal
device(config)# router bgp
device(config-bgp-router)# local-as 1
device(config-bgp-router)# neighbor 1.1.1.1 remote-as 2
device(config-bgp-router)# address-family ipv4 unicast
device(config-bgp-ipv4u)# graceful-restart
%Warning: Please clear the neighbor session for the parameter change to take effect!
device(config-bgp-ipv4u)# graceful-restart purge-time 240

The following example sets the restart time to 60 seconds.

device# configure terminal
device(config)# router bgp
device(config-bgp-router)# local-as 1
device(config-bgp-router)# neighbor 1.1.1.1 remote-as 2
device(config-bgp-router)# address-family ipv4 unicast
device(config-bgp-ipv4u)# graceful-restart
%Warning: Please clear the neighbor session for the parameter change to take effect!
device(config-bgp-ipv4u)# graceful-restart restart-time 60
%Warning: Please clear the neighbor session for the parameter change to take effect!

The following example sets the stale-routes time to 180 seconds.

device# configure terminal
device(config)# router bgp
device(config-bgp-router)# local-as 1
device(config-bgp-router)# neighbor 1000::1 remote-as 2
device(config-bgp-router)# address-family ipv6 unicast
device(config-bgp-ipv6u)# neighbor 1000::1 activate
device(config-bgp-ipv6u)# graceful-restart
%Warning: Please clear the neighbor session for the parameter change to take effect!
device(config-bgp-ipv6u)# graceful-restart stale-routes-time 180
%Warning: Please clear the neighbor session for the parameter change to take effect!

The following example enables the BGP graceful restart capability and sets the purge time to 220 seconds in L2VPN EVPN configuration mode.

device# configure terminal
device(config)# router bgp
device(config-bgp-router)# address-family l2vpn evpn
device(config-bgp-evpn)# graceful-restart purge-time 220