Filter BGP route based on ospf_metric1 ?

[Douglas Fischer]

Wow... I'm a bit surprised knowing that.

One scenario that I used in some customers is to used the IGP metric to
populate the BGP MED. But I did it on Juniper, Huawei, and Cisco.
I never needed it on Bird.

By what you described, I presume.
If I can't test that IGP attribute, probably I also won't be able to pass
that info to MED.

Does it makes sense?

Em qui., 24 de mar. de 2022 04:41, Maria Matejka <maria.matejka at nic.cz>
escreveu:

> Hello!
>
> > Our routers speak OSPF and have a full mesh of BGP connections for our
> > internal routes. This works quite well.
> >
> > One router sees the other through OSPF:
> >
> > 80.241.60.8/32     via 10.25.19.251 on bond0.19 [ospf1 2022-03-17] * I
> > (150/2474) [80.241.60.8]
> >          Type: OSPF unicast univ
> >          OSPF.metric1: 2474
> >          OSPF.metric2: 16777215
> >          OSPF.tag: 0x00000000
> >          OSPF.router_id: 80.241.60.8
> >
> > The BGP session is established to 80.241.60.8 and e.g. this route is
> > learned:
> >
> > 192.168.100.0/22   via 10.25.19.251 on bond0.19 [thor 2022-03-17 from
> > 80.241.60.8] * (100/2474) [i]
> >          Type: BGP unicast univ
> >          BGP.origin: IGP
> >          BGP.as_path:
> >          BGP.next_hop: 80.241.60.8
> >          BGP.local_pref: 100
> >
> > In the first line the ospf_metric1 is shown: (100/2474)
> > But when I try to filter on it (because I want to drop routes with a too
> > high metric),
> > the route attribute ospf_metric1 is "(void)".
> >
> > This seems to be because it's a BGP route and not an OSPF route.
> >
> > Is it somehow possible to achieve this?
>
> The OSPF metric is copied there as an inaccessible "igp_metric"
> attribute. This is quite a silly behavior and in fact, I'm just a
> handful of commits before enabling filtering by this general attribute.
>
> This change will happen in a branch that should eventually merge into
> some future v2.0.x branch as well as the v3 branch. We won't backport it
> into v1.6.x.
>
> Maria
>
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