Configuring Bgp Fast Fall-Over - Dell Z9000 Configuration Manual

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Configuring BGP Fast Fall-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

fall-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 fall-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 fall-over feature is configured on a per-neighbor or peer-group basis and is disabled by

To enable the BGP fast fall-over feature, use the following command.

To disable fast fall-over, use the [no] neighbor [neighbor | peer-group] fall-over command

in CONFIGURATION ROUTER BGP mode.

Enable BGP Fast fall-Over.

CONFIG-ROUTER-BGP mode

neighbor {ip-address | peer-group-name} fall-over

Example of Verifying that Fast fall-Over is Enabled on a BGP Neighbor

Example of Verifying that Fast fall-Over is Enabled on a Peer-Group

To verify fast fall-over is enabled on a particular BGP neighbor, use the show ip bgp neighbors

command. Because fast fall-over is disabled by default, it appears only if it has been enabled (shown in

Dell#sh ip bgp neighbors

BGP neighbor is 100.100.100.100, remote AS 65517, internal link

Member of peer-group test for session parameters

BGP version 4, remote router ID 30.30.30.5

BGP state ESTABLISHED, in this state for 00:19:15

Last read 00:00:15, last write 00:00:06

Hold time is 180, keepalive interval is 60 seconds

Received 52 messages, 0 notifications, 0 in queue

Sent 45 messages, 5 notifications, 0 in queue

Received 6 updates, Sent 0 updates

Route refresh request: received 0, sent 0

Minimum time between advertisement runs is 5 seconds

Minimum time before advertisements start is 0 seconds

Capabilities received from neighbor for IPv4 Unicast :

MULTIPROTO_EXT(1)

ROUTE_REFRESH(2)

Border Gateway Protocol IPv4 (BGPv4)