Border Gateway Protocol | 207BGP fast fall-overBy default, a BGP session is governed by the hold time. BGP routers typically carry large routing tables, sofrequent session resets are not desirable. The BGP fast fall-over feature reduces the convergence timewhile maintaining stability. The connection to a BGP peer is immediately reset if a link to a directlyconnected external peer fails.When fall-over is enabled, BGP tracks IP reachability to the peer remote address and the peer localaddress. Whenever either address becomes unreachable (for example, no active route exists in the routingtable for peer IPv6 destinations/local address), BGP brings down the session with the peer.The BGP fast fall-over feature is configured on a per-neighbor or peer-group basis and is disabled bydefault.To disable Fast Fall-Over, use the [no] neighbor [neighbor | peer-group] fall-over command inCONFIGURATION ROUTER BGP modeUse the show ip bgp neighbors command as shown in Figure 9-22 to verify that fast fall-over is enabledon a particular BGP neighbor. Note that since Fast Fall-Over is disabled by default, it will appear only if ithas been enabled.Command Syntax Command Mode Purposeneighbor {ip-address |peer-group-name} fall-overCONFIG-ROUTER-BGP Enable BGP Fast Fall-Over
