ospf virtual link not coming up

[Ondrej Zajicek]

On Thu, Nov 29, 2012 at 02:16:04PM +0100, Martin Kraus wrote:
> I managed to get the vlink up. I'm using ptp on a broadcast network to get rid of the DR/BDR
> timeout. All the segments are ethernet. I assumed that is a correct way to do it but I might 
> be wrong. I'm actually using gns3 to do the simulations but that shouldn't
> matter.

...

> 10.4.7.1 is running bird. It's connected to 192.168.60.1(R3) and that in turn is
> connected to 192.168.70.1(R4).
> 
> the vlink is setup between 10.4.8.1 (on RID 10.4.7.1) and 10.5.1.1 (on RID
> 196.168.70.1)
> 
> The way to get the vlink on bird working was to set the ospf between R3 and
> R4 to broadcast. Cisco could determine the vlink ip address on the linux box
> on the ptp network and when I setup another cisco router in place of 10.4.7.1
> I could get the vlink up over the ptp network as well.
> 
> How is the peer ip address determined? I don't see it in any of the LSAs.

Hello

This is a problematic issue in OSPFv2. IP address of remote vlink
endpoint is determined from an IP address of a link to border router,
which is OK if this is broadcast network, but may not work for ptp
network (where the value may be either IP or a local interface index,
while the local router cannot know what it is). Cisco is probably more
relaxed and just try the value anyway, while BIRD does not deduce IP
address in this case.

-- 
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."
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