Administrator Guide

• keepalive: the range is from 1 to 65535. Time interval, in seconds, between keepalive messages sent to the neighbor routers.
The default is 60 seconds.
• holdtime: the range is from 3 to 65536. Time interval, in seconds, between the last keepalive message and declaring the router
dead. The default is 180 seconds.
• Configure timer values for all neighbors.
CONFIG-ROUTER-BGP mode
timers bgp keepalive holdtime
• keepalive: the range is from 1 to 65535. Time interval, in seconds, between keepalive messages sent to the neighbor routers.
The default is
60 seconds.
• holdtime: the range is from 3 to 65536. Time interval, in seconds, between the last keepalive message and declaring the router
dead. The default is 180 seconds.
To view non-default values, use the show config command in CONFIGURATION ROUTER BGP mode or the show running-
config bgp command in EXEC Privilege mode.
Setting the extended timer
To configure BGP idle hold time, use the following commands.
Timer values configured with the neighbor timers extended command override the timer values configured with the timers
bgp extended command.
The peer remains in idle state based on the configured idle-holdtime. The less the idle-holdtime, lesser the peer remains in idle
state.
NOTE:
For the new idle-holdtime to take effect, you need to shutdown the respective peer manually using neighbor
shutdown command and enable the peer again.
• Configure idle-holdtime values for a BGP neighbor or peer group.
CONFIG-ROUTER-BGP mode
neighbors {ip-address | ipv6-address | peer-group-name} timers extended idle-holdtime
idle-holdtime: the range is from 1 to 32767. Time interval, in seconds, during which the peer remains in idle state. The default is
15 seconds.
• Configure idle-holdtime values for all BGP neighbors.
CONFIG-ROUTER-BGP mode
timers bgp extended idle holdtime
idle-holdtime: the range is from 1 to 32767. Time interval, in seconds, during which the peer remains in idle state. The default is
15 seconds.
Enabling BGP Neighbor Soft-Reconfiguration
BGP soft-reconfiguration allows for faster and easier route changing.
Changing routing policies typically requires a reset of BGP sessions (the TCP connection) for the policies to take effect. Such resets cause
undue interruption to traffic due to hard reset of the BGP cache and the time it takes to re-establish the session. BGP soft reconfig allows
for policies to be applied to a session without clearing the BGP Session. Soft-reconfig can be done on a per-neighbor basis and can either
be inbound or outbound.
BGP soft-reconfiguration clears the policies without resetting the TCP connection.
To reset a BGP connection using BGP soft reconfiguration, use the clear ip bgp command in EXEC Privilege mode at the system
prompt.
When you enable soft-reconfiguration for a neighbor and you execute the clear ip bgp soft in command, the update database
stored in the router is replayed and updates are reevaluated. With this command, the replay and update process is triggered only if a
route-refresh request is not negotiated with the peer. If the request is indeed negotiated (after execution of
clear ip bgp soft
in), BGP sends a route-refresh request to the neighbor and receives all of the peer’s updates.
To use soft reconfiguration (or soft reset) without preconfiguration, both BGP peers must support the soft route refresh capability, which
is advertised in the open message sent when the peers establish a TCP session.
To determine whether a BGP router supports this capability, use the show ip bgp neighbors command. If a router supports the
route refresh capability, the following message displays:
Received route refresh capability from peer.
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Border Gateway Protocol IPv4 (BGPv4)