BGP-GR timers related issues

[abhishekgarg658545708]

Hi Team,

                  i have one query if we change the IBGP over loopback  GR (switchover timers to warm reboot timers ) so in this case do we need to do

clear ip bgp

(hard reset)  for negotiate the timers  or will it automatically negotiate 

[M02@rt37]

Hello @abhishekgarg658545708 

When you make changes to the BGP timers, such as transitioning from IBGP over a loopback with switchover timers to warm reboot timers, BGP generally doesn't automatically renegotiate the timers. In many cases, you would need to clear the BGP sessions to apply the new timers.

The command

clear ip bgp

with the `soft` option is often used for this purpose. It triggers a soft reset, which attempts to re-establish BGP sessions gracefully without tearing down the entire BGP process. This allows the router to negotiate any changes, including timer adjustments, without causing a complete disruption.

clear ip bgp * soft

This command clears all BGP sessions gracefully.

[abhishekgarg658545708]

Hi M02@rt37 

i think

clear ip bgp * soft

command can't hep to re-negotiate the timers (it is generally for prefixes and policies ) , we need to perform hard reset then only BGP open message will send 

[M02@rt37]

So @abhishekgarg658545708, Hard reset this iBGP peering. It is not automatic.

Thanks for your feedback.

[MHM Cisco World]

We dont have other option

Change timer in one router and check time in other router with 

Shwo ip bgp neighbors x.x.x.x

If the timer show modify one no need hard reset if not change then you need to reset the connection.

MHM

[MHM Cisco World · Accepted solution]

when you adjust the timer immediate you get message to reset all bgp sessoin