Users Guide

Neighbor fall-over
The BGP neighbor fall-over feature reduces the convergence time while maintaining stability. When you enable fall-over, BGP
tracks IP reachability to the peer remote address and the peer local address.
When remote or peer local addresses become unreachable, BGP brings the session down with the peer. For example, if no
active route exists in the routing table for peer IPv6 destinations/local address, BGP brings the session down.
By default, the hold time governs a BGP session. Configure BGP fast fall-over on a per-neighbor or peer-group basis. BGP
routers typically carry large routing tables as frequent session resets are not desirable. If you enable fail-over, the connection to
an internal BGP peer is immediately reset if the host route added to reach the internal peer fails.
1. Enter the neighbor IP address in ROUTER-BGP mode.
neighbor ip-address
2. Disable fast fall-over in ROUTER-NEIGHBOR mode.
no fall-over
3. Enter the neighbor IP address in ROUTER-BGP mode.
neighbor ip-address
4. Enable BGP fast fall-Over in ROUTER-NEIGHBOR mode.
fall-over
Configure neighbor fall-over
OS10(config)# router bgp 100
OS10(config-router-bgp-100)# neighbor 3.1.1.1
OS10(config-router-neighbor)# remote-as 100
OS10(config-router-neighbor)# fall-over
OS10(config-router-neighbor)# no shutdown
Verify neighbor fall-over on neighbor
OS10(config-router-neighbor)# do show ip bgp neighbors 3.1.1.1
BGP neighbor is 3.1.1.1, remote AS 100, local AS 100 internal link
BGP version 4, remote router ID 3.3.3.33
BGP state ESTABLISHED, in this state for 00:17:17
Last read 00:27:54 seconds
Hold time is 180, keepalive interval is 60 seconds
Configured hold time is 180, keepalive interval is 60 seconds
Fall-over enabled
Received 23 messages
1 opens, 0 notifications, 1 updates
21 keepalives, 0 route refresh requests
Sent 21 messages
1 opens, 0 notifications, 0 updates
20 keepalives, 0 route refresh requests
Minimum time between advertisement runs is 30 seconds
Minimum time before advertisements start is 0 seconds
Capabilities received from neighbor for IPv4 Unicast:
MULTIPROTO_EXT(1)
ROUTE_REFRESH(2)
CISCO_ROUTE_REFRESH(128)
4_OCTET_AS(65)
Capabilities advertised to neighbor for IPv4 Unicast:
MULTIPROTO_EXT(1)
ROUTE_REFRESH(2)
CISCO_ROUTE_REFRESH(128)
4_OCTET_AS(65)
Prefixes accepted 3, Prefixes advertised 0
Connections established 1; dropped 0
Last reset never
For address family: IPv4 Unicast
Allow local AS number 0 times in AS-PATH attribute
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Layer 3