Configuring Bgp Fast Fall-Over - Dell Z9500 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 default.

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

Examples of Verifying that Fast fall-Over is Enabled on a BGP Neighbor and a Peer-Group

To verify that you enabled fast fall-over 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 bold).

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

Border Gateway Protocol IPv4 (BGPv4)