BGP graceful-restart and fast-external-fallover

[vishal_bhugra]

BGP Fast-external-fallover command allows directly connected peers to immediately reset external BGP peering sessions if the link goes down.

BGP Graceful restart allows processing of the data packet over the stale paths.

My question is, How BGP will behave if I will enable both the features at same time.

[Giuseppe Larosa · Accepted solution]

Hello Vishal,

BGP graceful restart is a feature for network devices with two route processors and hardware based packet forwarding that allows to handle the route processor switchover in cooperation with the BGP neighbors.

This capability can be negotiated at BGP session setup and allows for the restarting node to advise the BGP peers in case of router processor switchover. The BGP peers will wait for a time interval to see again messages from the new master route processor and can hide all the process from the rest of the network.

fast external fallover is now enabled by default on eBGP sessions and works as you have described

The two features can be enabled together, but they serve different purposes

Hope to help

Giuseppe

[vishal_bhugra]

Thanks Giuseppe