2 Replies Latest reply: Oct 16, 2019 5:48 PM by Kevin Santillan RSS

    BGP Fall-over bfd and Gracefull Restart

    Cuong

      Hello all,

       

      Could I use both graceful-restart and fall-over bfd in one configuration?

      router bgp 65001

      bgp log-neighbor-changes

      bgp graceful-restart

      network 10.224.9.140 mask 255.255.255.252

      neighbor 10.224.9.141 remote-as 64001

      neighbor 10.10.9.141 password 7 110B2A5644112938597824223F

      neighbor 10.10.9.141 timers 15 45

      neighbor 10.10.9.141 send-community

      neighbor 10.10.9.141 advertisement-interval 0

      neighbor 10.10.9.141 route-map BGP-INTO-IGP out

      neighbor 10.10.9.146 remote-as 12641

      neighbor 10.10.9.146 password 7 070D121F1D0A3B314A40040A13

      neighbor 10.10.9.146 update-source GigabitEthernet0/0/0.5018

      neighbor 10.10.9.146 timers 15 45

      neighbor 10.10.9.146 fall-over bfd

      neighbor 10.10.9.146 send-community

      neighbor 10.10.9.146 advertisement-interval 0

      ip bgp-community new-format

        • 1. Re: BGP Fall-over bfd and Gracefull Restart
          Vaclav

          Hi,

          I believe that this won't be a problem during Switchover where the other site will switch from RP1 to RP2 because the interface will be still up but otherwise the session will go down.

           

          V.

          • 2. Re: BGP Fall-over bfd and Gracefull Restart
            Kevin Santillan

            I tested this on CSR1KVs running 03.14.02 and the config got accepted and was working. That is, BFD is up and both routers know that their peers are Graceful Restart capable.

             

            R1#sh ip bgp nei | i Grace|BF

            BFD is configured. BFD peer is Up. Using BFD to detect fast fallover (single-hop).

                Graceful Restart Capability: advertised and received

              Graceful-Restart is enabled, restart-time 120 seconds, stalepath-time 360 seconds

             

            However, this isn't recommended since running BFD per neighbor and running Graceful Restart for the whole process is counterintuitive. In platforms that support NSF, Graceful Restart will allow traffic to still be forwarded via an interface or link that was detected by BFD as down which isn't desirable. If you really require Graceful Restart, what you can do is configure it on a per neighbor basis via neighbor x.x.x.x ha-mode graceful-restart so that the capability won't be exchanged on peers you're running BFD with.