bfd configuration

[Joel Dahl]

On Wed, Feb 13, 2019 at 02:31:41PM +0100, Bernd Naumann wrote:
> Hi Joel,
> 
> On 12.02.19 21:08, Joel Dahl wrote:
> > Hi,
> > 
> > I've enabled bfd on an iBGP session between two routers. The routers are directly connected, just L2.
> > 
> > Taking down the iBGP session (in this case, rebooting the router) results in the following which I find a bit confusing:
> > 
> > # birdc show proto
> > BIRD 2.0.3 ready.
> > Name       Proto      Table      State  Since         Info
> > bfd_ibgp_v4 BFD        ---        up     2019-02-11
> > ibgp_v4    BGP        ---        start  20:59:33.284  Connect       Received: Administrative shutdown
> > 
> > Why is bfd still in "up" state?
> > 
> > Configuration from one of the routers:
> > 
> > protocol bfd bfd_ibgp_v4 {
> >         interface "igb2" {
> >                 multiplier 3;
> >                 interval 500 ms;
> >                 idle tx interval 1000 ms;
> >         };
> >         neighbor X.X.1.6 dev "igb2";
> > }
> > 
> > protocol bgp ibgp_v4 {
> > 	local X.X.1.5 as 11111;
> > 	neighbor X.X.1.6 as 11111;
> > 	bfd on;
> > 	ipv4 {
> > 		import all;
> > 		export all;
> > 		next hop self;
> > 	};
> > }
> > 
> 
> I think because the proto bfd is independent from dynamic routing
> protocols, because you need at minimum the config stanza for bfd and
> then enable the usage of bfd for bgp or ospf anyway to make use of it;
> for reason you could have only running bfd on its own (but I don't know
> for what benefit).
> 
> In case of keepalived you could have booth, vrrp and bfd.

So the bfd state being "up" has nothing to do with the actual session with the
neighbor being up or down?

-- 
Joel