Difference between BGP Prefix independent convergence and bgp advertise best external

[shreerampardhy]

Hello All,

Please can someone advice what is the difference between the BGP Prefix independent convergence and BGP advertise best path external feature?

Are these two linked in any way? From what i understand, the best path feature would allow parallel paths to be advertised to the remote neighbour. The PIC feature would allow the router to install backup path in RIB, CEF and MPLS forwarding tables.

Regards,

Shreeram

[Sherif Atef Ahmed Ismail]

Hello Shreeram

Yes you are correct.

Please note that BGP best external will only be needed in case you are using policies on your PE which is usually the case

i.e

If a dual CE site is meshed to dual PE, usually backup PE advertizes its route with a local preference less than that of primary PE. As a result remote PE will only receive the route from primary PE when all PE routers are meshed to RR which is usually the case. In this case you would need this feature so that backup PE can advertize its backup route

However If you are not using any policies on your PE, then remote PE would receive both routes normally so no need for this feauture

In both cases, you would need BGP PIC so remote router can install the backup route in data plane

Hope you find this useful

Regards

Sherif Ismail

[shreerampardhy]

Hello Sherif,

Many thanks for the update.

Shreeram