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To enable a peer group, use the neighbor peer-group-name no shutdown command in CONFIGURATION ROUTER
BGP mode (shown in bold).
Dell(conf-router_bgp)#neighbor zanzibar no shutdown
Dell(conf-router_bgp)#show config
!
router bgp 45
bgp fast-external-fallover
bgp log-neighbor-changes
neighbor zanzibar peer-group
neighbor zanzibar no shutdown
neighbor 10.1.1.1 remote-as 65535
neighbor 10.1.1.1 shutdown
To disable a peer group, use the neighbor peer-group-name shutdown command in CONFIGURATION ROUTER BGP
mode. The configuration of the peer group is maintained, but it is not applied to the peer group members. When you disable a
peer group, all the peers within the peer group that are in the ESTABLISHED state move to the IDLE state.
To view the status of peer groups, use the show ip bgp peer-group command in EXEC Privilege mode, as shown in the
following example.
Dell>show ip bgp peer-group
Peer-group zanzibar, remote AS 65535
BGP version 4
Minimum time between advertisement runs is 5 seconds
For address family: IPv4 Unicast
BGP neighbor is zanzibar, peer-group internal,
Number of peers in this group 26
Peer-group members (* - outbound optimized):
10.68.160.1
10.68.161.1
10.68.162.1
10.68.163.1
10.68.164.1
10.68.165.1
10.68.166.1
10.68.167.1
10.68.168.1
10.68.169.1
10.68.170.1
10.68.171.1
10.68.172.1
10.68.173.1
10.68.174.1
10.68.175.1
10.68.176.1
10.68.177.1
10.68.178.1
Configuring BGP Fast Fail-Over
By default, a BGP session is governed by the hold time.
BGP routers typically carry large routing tables, so frequent session resets are not desirable. The BGP fast fail-over feature
reduces the convergence time while maintaining stability. The connection to a BGP peer is immediately reset if a link to a
directly connected external peer fails.
When you enable fail-over, BGP tracks IP reachability to the peer remote address and the peer local address. Whenever either
address becomes unreachable (for example, no active route exists in the routing table for peer IPv6 destinations/local address),
BGP brings down the session with the peer.
The BGP fast fail-over feature is configured on a per-neighbor or peer-group basis and is disabled by default.
To enable the BGP fast fail-over feature, use the following command.
To disable fast fail-over, use the [no] neighbor [neighbor | peer-group] fail-over command in
CONFIGURATION ROUTER BGP mode.
178
Border Gateway Protocol IPv4 (BGPv4)