Description

The log entry "BGP_CEASE_PREFIX_LIMIT_EXCEEDED" indicates that a BGP session was terminated because the number of prefixes (routes) received from a peer exceeded the configured maximum prefix limit.


This event is triggered as part of a protective mechanism designed to maintain router performance and network stability. Receiving an excessive number of routes from a BGP peer can:

  •  Overwhelm the router's memory
  •  Cause degraded performance
  •  Introduce instability into the routing table
  •  Configuration changes under policies

Symptoms

The following log is observed.

Sep 5 02:12:21 hostname rpd[27377]: BGP_CEASE_PREFIX_LIMIT_EXCEEDED: 10.5.0.10 (External AS xxxx): Shutting down peer due to exceeding configured maximum prefix-limit(100) for inet-unicast nlri: 101

 

Solution

  • Set reasonable prefix limits and other parameters based on expected routing behaviour
Here are sample commands to set the parameters
 
set protocols bgp group test-bgp family inet unicast prefix-limit maximum <>
set protocols bgp group test-bgp family inet unicast prefix-limit teardown <>
set protocols bgp group test-bgp family inet unicast prefix-limit idle-timeout <>
 
If you increase the prefix limit after the session has been torn down due to exceeding the previous limit, the session will not come back immediately but will remain down for the configured idle timeout unless you manually clear the neighbor session using the command

 

clear bgp neighbor <peer-ip>

 

  • Monitor BGP peer statistics regularly.
  • Use route filtering to control the number and type of prefixes received from peers.

 

Modification History

2025-10-03 : Article Created