Administrator Guide

To verify that fast fail-over is enabled on a peer-group, use the show ip bgp peer-group command (shown in bold).
Dell#sh ip bgp peer-group
Peer-group test
fail-over enabled
BGP version 4
Minimum time between advertisement runs is 5 seconds
For address family: IPv4 Unicast
BGP neighbor is test
Number of peers in this group 1
Peer-group members (* - outbound optimized):
100.100.100.100*
Dell#
router bgp 65517
neighbor test peer-group
neighbor test fail-over
neighbor test no shutdown
Conguring Passive Peering
When you enable a peer-group, the software sends an OPEN message to initiate a TCP connection.
If you enable passive peering for the peer group, the software does not send an OPEN message, but it responds to an OPEN message.
When a BGP neighbor connection with authentication congured is rejected by a passive peer-group, the system does not allow another
passive peer-group on the same subnet to connect with the BGP neighbor. To work around this, change the BGP conguration or change
the order of the peer group conguration.
You can constrain the number of passive sessions accepted by the neighbor. The limit keyword allows you to set the total number of
sessions the neighbor will accept, between 2 and 256. The default is
256 sessions.
1 Congure a peer group that does not initiate TCP connections with other peers.
CONFIG-ROUTER-BGP mode
neighbor peer-group-name peer-group passive limit
Enter the limit keyword to restrict the number of sessions accepted.
2 Assign a subnet to the peer group.
CONFIG-ROUTER-BGP mode
neighbor peer-group-name subnet subnet-number mask
The peer group responds to OPEN messages sent on this subnet.
3 Enable the peer group.
CONFIG-ROUTER-BGP mode
neighbor peer-group-name no shutdown
4 Create and specify a remote peer for BGP neighbor.
CONFIG-ROUTER-BGP mode
neighbor peer-group-name remote-as as-number
Only after the peer group responds to an OPEN message sent on the subnet does its BGP state change to ESTABLISHED. After the peer
group is ESTABLISHED, the peer group is the same as any other peer group.
For more information about peer groups, refer to Conguring Peer Groups.
190
Border Gateway Protocol IPv4 (BGPv4)