Configuring BGP4
December 2005 © Foundry Networks, Inc. 21 - 21
When you apply the new option to shut down a neighbor, the option takes place immediately and remains in effect
until you remove the option. If you save the configuration to the startup-config file, the shutdown option remains in
effect even after a software reload.
NOTE: The software also contains an option to end the session with a BGP4 neighbor and thus clear the routes
learned from the neighbor. Unlike this clear option, the option for shutting down the neighbor can be saved in the
startup-config file and thus can prevent the Layer 3 Switch from establishing a BGP4 session with the neighbor
even after reloading the software.
NOTE: If you notice that a particular BGP4 neighbor never establishes a session with the Foundry Layer 3
Switch, check the Layer 3 Switch’s running-config and startup-config files to see whether the configuration
contains a command that is shutting down the neighbor. The neighbor may have been shut down previously by an
administrator.
To shut down a BGP4 neighbor, enter commands such as the following:
FESX424 Router(config)# router bgp
FESX424 Router(config-bgp-router)# neighbor 209.157.22.26 shutdown
FESX424 Router(config-bgp-router)# write memory
Syntax: [no] neighbor <ip-addr> shutdown
The <ip-addr> parameter specifies the IP address of the neighbor.
Optional Configuration Tasks
The following sections describe how to perform optional BGP4 configuration tasks.
Changing the Keep Alive Time and Hold Time
The Keep Alive Time specifies how frequently the router will send KEEPALIVE messages to its BGP4 neighbors.
The Hold Time specifies how long the router will wait for a KEEPALIVE or UPDATE message from a neighbor
before concluding that the neighbor is dead. When the router concludes that a BGP4 neighbor is dead, the router
ends the BGP4 session and closes the TCP connection to the neighbor.
The default Keep Alive time is 60 seconds. The default Hold Time is 180 seconds. To change the timers, use
either of the following methods.
NOTE: Generally, you should set the Hold Time to three times the value of the Keep Alive Time.
NOTE: You can override the global Keep Alive Time and Hold Time on individual neighbors. See “Adding BGP4
Neighbors” on page 21-12.
To change the Keep Alive Time to 30 and Hold Time to 90, enter the following command:
FESX424 Router(config-bgp-router)# timers keep-alive 30 hold-time 90
Syntax: timers keep-alive <num> hold-time <num>
For each keyword, <num> indicates the number of seconds. The Keep Alive Time can be 0 – 65535. The Hold
Time can be 0 or 3 – 65535 (1 and 2 are not allowed). If you set the Hold Time to 0, the router waits indefinitely for
messages from a neighbor without concluding that the neighbor is dead.
Changing the BGP4 Next-Hop Update Timer
By default, the Layer 3 Switch updates its BGP4 next-hop tables and affected BGP4 routes five seconds after IGP
route changes. You can change the update timer to a value from 1 – 30 seconds.
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