changing bgp_med attributes cause route been filited

Douglas Fischer fischerdouglas at gmail.com
Thu Jul 27 13:32:06 CEST 2023


This reminds me of a meme...
https://img-comment-fun.9cache.com/media/ay9BKnV/aWlGMBgm_700w_0.jpg

Em qua., 26 de jul. de 2023 às 20:54, Ondrej Zajicek <santiago at crfreenet.org>
escreveu:

> On Thu, Jul 20, 2023 at 08:25:24PM +0800, Brandon Zhi wrote:
> > Hi all,
> >
> > I was doing research about selecting the best route on multiple nodes
> based
> > on bgp_med attributes.
> >
> >
> > My idea is to add bgp_med value between each node based on ping, and then
> > bird will select the route which has the lowest bgp_med value (which is
> the
> > total ping delay)
> >
> > But some routes will be filled, which i don't want it.
> >
> > I found that the code " bgp_med = bgp_med + bgp_med_ping + bgp_med_ping;"
> > will cause some routes to be filtered.
> >
> > Can someone tell me why? I only want to modify bgp_med and don't want my
> > routes to be filtered.
>
> Hi
>
> Perhaps there are some error in logs about filter failures? I guess that
> when bgp_med is not defined, then expression 'bgp_med + X' fails.
>
> You could try something like:
>
>   if (defined(bgp_med))
>     bgp_med = bgp_med + X;
>   else
>     bgp_med = X;
>
>
> And perhaps even better than use bgp_med for this is to use bgp_aigp
> attribute and associated BGP options (aigp, cost).
>
> --
> Elen sila lumenn' omentielvo
>
> Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
> OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
> "To err is human -- to blame it on a computer is even more so."
>


-- 
Douglas Fernando Fischer
Engº de Controle e Automação
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