BGP multipath with RR

The idea is to receive more than one path – i.e the best path calculate by the RR)

All routers are connected to the RR.

Extract of the configuration on the RR

router bgp 65000
bgp router-id 10.1.1.1
bgp log-neighbor-changes
bgp additional-paths select best 2
bgp additional-paths send
neighbor IBGP peer-group
neighbor IBGP remote-as 65000
neighbor IBGP update-source Loopback0
neighbor IBGP route-reflector-client
neighbor IBGP advertise additional-paths best 2
maximum-paths ibgp 2

The RR accepts two paths, and advertise additional paths on the same session.

Extract on one bgp client

router bgp 65000
bgp router-id 10.1.1.2
bgp log-neighbor-changes
neighbor 10.1.1.1 remote-as 65000
neighbor 10.1.1.1 update-source Loopback0
neighbor 10.1.1.1 next-hop-self
neighbor 10.1.1.1 additional-paths receive
maximum-paths ibgp 2

The client supports two paths and could receive more than one path from the same neighbor.

More information:

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_bgp/configuration/xe-16/irg-xe-16-book/bgp-additional-paths.html