Command:

bgp log-neighbor-changes


Mode:

Router(config-router)#
Router(config-router-af)#


Syntax:

bgp log-neighbor-changes
no bgp log-neighbor-changes

 

Syntax Description:

This command has no arguments or keywords.

 

Command Description:

To enable logging of BGP neighbor resets, use the bgp log-neighbor-changes command in address family or router configuration mode. To disable the logging of changes in BGP neighbor adjacencies, use the no form of this command.

BGP neighbor changes are logged by default in Cisco IOS Release 12.0(1) and later.

The bgp log-neighbor-changes command enables logging of BGP neighbor status changes (up or down) and resets for troubleshooting network connectivity problems and measuring network stability. Unexpected neighbor resets might indicate high error rates or high packet loss in the network and should be investigated.

Using the bgp log-neighbor-changes command to enable status change message logging does not cause a substantial performance impact, unlike, for example, enabling per BGP update debugging. If the UNIX syslog facility is enabled, messages are sent to the UNIX host running the syslog daemon so that the messages can be stored and archived. If the UNIX syslog facility is not enabled, the status change messages are retained in the internal buffer of the router, and are not stored to disk. You can set the size of this buffer, which is dependent upon the available RAM, using the logging buffered command.

The neighbor status change messages are not tracked if the bgp log-neighbor-changes command is not enabled, except for the reset reason, which is always available as output of the show ip bgp neighbors command.

The eigrp log-neighbor-changes command enables logging of Enhanced IGRP (EIGRP) neighbor adjacencies, but messages for BGP neighbors are logged only if they are specifically enabled with the bgp log-neighbor-changes command.

Use the show logging command to display the log for the BGP neighbor changes.


Example:

The following example logs neighbor changes for BGP in router configuration mode:

Router(config)# bgp router 100
Router(config-router)# bgp log-neighbor-changes


Misconceptions:

None


Related Commands:

logging buffered
show ip bgp ipv4
show ip bgp neighbors

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