[ixpmanager] BGP communities in Route Server

[Salvador Bertenbreiter]

Thank you for the clarification.

El jue., 27 de ago. de 2020 a la(s) 15:01, Barry O'Donovan (
barry.odonovan at inex.ie) escribió:

>
> Salvador Bertenbreiter wrote on 27/08/2020 19:41:
> > Cool, great Barry.
> > BTW, does the order of the communities affect the behavior like in BGP
> > filters? I mean, if I use "64500:64496" "64500:64503" "0:64500"  instead
> > of "0:64500" 64500:64496" "64500:64503", would it have a different
> effect?
>
> The relevant bit of config is:
>
>      # Implement widely used community filtering schema.
>      if (0, peerasn) ~ bgp_community then
>              return false;
>      if (routeserverasn, peerasn) ~ bgp_community then
>              return true;
>      if (0, routeserverasn) ~ bgp_community then
>              return false;
>
> which is contained in the function ixp_community_filter(peerasn) which
> is executed when determining if a route should be send to 'peerasn'.
>
> Remembering that the default is to advertise the route then you can see
> from the above that the order doesn't actually matter.
>
> In the above sequence:
>
> 1. if the route has the community 0:peerasn (do not advertise to
> peerasn) in any location, then the route is NOT advertised and finish
> processing the route
>
> 2. if the route has the community rs-asm:peerasn (do advertise to
> peerasn) in any location, then the route is advertised and finish
> processing the route.
>
> 3. if the route has 0:rs-asn (do not advertise to all peers) then it is
> NOT advertised and finish processing the route.
>
> 4. not shown above but the default decision: advertise.
>
> Hope that makes sense,
>
>   - Barry
>
>
>
>
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