Reference Guide

Border Gateway Protocol IPv4 (BGPv4) | 263
Change BGP timers
Use either or both of the following commands in the CONFIGURATION ROUTER BGP mode to
configure BGP timers.
Use the
show config command in CONFIGURATION ROUTER BGP mode or the show running-config
bgp
command in EXEC Privilege mode to view non-default values.
Timer values configured with the
neighbor timers command override the timer values configured with the
timers bgp command.
When two neighbors, configured with different
keepalive and holdtime values, negotiate for new values, the
resulting values will be as follows:
• the lower of the
holdtime values is the new holdtime value, and
• whichever is the lower value; one-third of the new
holdtime value, or the configured keepalive value is
the new
keepalive value.
BGP neighbor soft-reconfiguration
Changing routing policies typically requires a reset of BGP sessions (the TCP connection) for the policies
to take effect. This type of reset causes undue interruption to traffic due to the hard reset of the BGP cache
and the time it takes to re-establish the session.
BGP soft reconfiguration allows you to re-apply policies to a session without resetting the BGP session.
You can perform soft reconfiguration on a per-neighbor basis for either inbound or outbound policies. BGP
soft reconfiguration clears and reapplies policies without resetting the TCP connection.
Command Syntax Command Mode Purpose
neighbors {ip-address |
peer-group-name} timers keepalive
holdtime
CONFIG-ROUTER-
BGP
Configure timer values for a BGP neighbor or peer
group.
•
keepalive range: 1 to 65535. Time interval, in
seconds, between keepalive messages sent to the
neighbor routers. (Default: 60 seconds)
•
holdtime range: 3 to 65536. Time interval, in
seconds, between the last keepalive message and
declaring the router dead. (Default: 180 seconds)
timers bgp keepalive holdtime CONFIG-ROUTER-
BGP
Configure timer values for all neighbors.
•
keepalive range: 1 to 65535. Time interval, in
seconds, between keepalive messages sent to the
neighbor routers. (Default: 60 seconds)
•
holdtime range: 3 to 65536. Time interval, in
seconds, between the last keepalive message and
declaring the router dead. (Default: 180 seconds)