bird vs cisco/quagga

[Борис Коваленко]

Ok, Martin. Let speak in general. The topology is very simple:
There is set of "area" routers speaking with "core" router by ospf. Core
router has "supernet" routed to null (ip route X.X.X.X/20 null0) to avoid
forwading loops to unallocated IPs. And it also injects this route into
ospf and bgp with "redistribute static". When route is injected into bgp it
gets some communities for further processing. Core router is speaking to
border router by ospf and bgp. So on border router we get two routes
X.X.X.X/20 ospf E2 type, and X.X.X.X/20 ibgp. OSPF wins, and route can not
be announced to ebgp peers. What do You suggest? Change preference for OSPF
- so we break igp?

This is my knowlegde from cisco/quagga world. And it does not work with
bird. Where is my mistake?

Regards,
Boris


пн, 27 февр. 2017 г. в 16:50, Martin Mares <mj at ucw.cz>:

> Hello!
>
> > I'm newbie to bird. Used cisco/quagga before. But filter language of bird
> > is very nice, so I want to try it. But I have one big misunderstanding.
> > With other vendors each protocol has it own routing table. So OSPF may
> work
> > only with ospf prefixes, BGP with bgp and so on. If we need protocol to
> get
> > access to other routing tables there are redistribute XXX commands.
> >
> > Unfortunatelly in bird there is one "super" table by default. So i get
> > sutiation where I have to prefixes on router, one from static protocol,
> and
> > one from ibgp. Prefix from ibgp has some communities on it, and I use
> this
> > communities in filters to ebgp. But static prefix always win. By some
> > reason I can't remove static prefix and use ibgp prefix and also can't
> add
> > communities to static prefix as they are changed by other router.
>
> Generally speaking, what you export to other routers should be a subset of
> what you really use for forwarding packets. Otherwise you are inviting
> routing
> loops and other problems. (There are exceptions to this rule, for example
> when
> you are running a BGP route reflector, but I suspect it is not your case.)
>
> From this point of view, it does make much sense to me what you are trying
> to accomplish. If you use the static route for forwarding, you should
> export
> it via eBGP. If the static route is merely a backup for cases when iBGP is
> down, adjust its preference so that the iBGP route will be preferred.
>
>                                 Have a nice fortnight
> --
> Martin `MJ' Mares                          <mj at ucw.cz>   http://mj.ucw.cz/
> Faculty of Math and Physics, Charles University, Prague, Czech Rep., Earth
> "It is easier to port a shell than a shell script." -- Larry Wall
>
-- 

С уважением,
Борис Коваленко
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