Description

This article documents a change in behavior with the BGP Protocol Hold Time with a Graceful Routing Engine Switchover (GRES) in Junos OS 16.1 and higher.

Solution

When a Graceful Routing Engine Switchover (GRES) occurs, when NonStop Routing (NSR) is enabled, the BGP hold-time is set to 120 seconds during a switchover if the active hold-time is set to a value lower than 120 seconds. This is because a new primary router or switch may experience a routing protocol flap when using aggressive timers, so it is automatically set to 120 seconds ​to prevent such a routing protocol flap only during a switchover. Starting in Junos OS Release 16.1, BGP IO has been multi-threaded and there is no longer need to bump up the holdtimer; such as changing it to 120 seconds.

 

Modification History