ospf external type 2 and igp_metric

[Dave Johnson]

Ondrej Zajicek writes:
> On Thu, Jul 29, 2021 at 03:14:39PM -0400, Dave Johnson wrote:
> > 
> > 
> > Hi,
> > 
> > I'm trying to get igp_metric to work for iBGP based on an OSPF
> > metric.
> > 
> > 
> > Here's my setup:
> > 
> > I would like to make use of the iBGP igp_metric as a tie-breaker if
> > BGP gets down that far in the route selection process, however I can't
> > seem to get BGP to pick up the OSPF metric for other machine's
> > loopbacks.
> 
> 
> > The loopback is being imported using a proto direct as it's simply
> > from Linux's lo interface:
> > 
> >   root at archer:~# birdc show route 10.10.10.30/32 all
> >   BIRD 1.6.6 ready.
> >   10.10.10.30/32     dev lo [direct1 11:14:34] * (240)
> >           Type: device unicast univ
> >   root at archer:~# 
> 
> Hi
> 
> I would suggest to just set loopback as a stub iface in OSPF. You would
> end with regular OSPF route instead of OSPF-E2 route and it would be
> more consistent with how OSPF is supposed to used.
> 
> There were some issues that BIRD did not allow 'lo' as its iface (i think
> we changed that in some 2.0.x version but probably it is still true in
> 1.6.x version). In such case the simplest way is to use dummy iface
> instead of loopback iface.


Thanks a bunch, using an ospf stub instead of direct did the trick:


  root at ganges:~# birdc show route 128.0.128.0/20 table internet all
  BIRD 1.6.6 ready.
  128.0.128.0/20     via 10.10.13.1 on tun13 [bgp_reliant 14:50:00 from 10.10.10.31] * (100/15) [AS25513i]
        Type: BGP unicast univ
        BGP.origin: IGP
        BGP.as_path: 65002 65001 21700 8359 25513
        BGP.next_hop: 10.10.10.31
        BGP.local_pref: 100
        BGP.community: (0,199) (8359,100) (8359,5500) (8359,55277)
        BGP.large_community: (21700, 101, 3) (21700, 102, 840) (21700, 103, 1)
                   via 10.10.13.1 on tun13 [bgp_archer 14:50:00 from 10.10.10.30] (100/26) [AS25513i]
        Type: BGP unicast univ
        BGP.origin: IGP
        BGP.as_path: 64515 65534 20473 8359 25513
        BGP.next_hop: 10.10.10.30
        BGP.local_pref: 100
        BGP.community: (20473,200) (64515,44)
  root at ganges:~# 


-- 
Dave