Several ptmp OSPF sessions over a single interface

[Ruben Laban]

On 8/27/2012 1:58 PM, Ruben Laban wrote:
> Hello,
>
> I'm currently performing some experiments to find the "best" way to
> inter-connect a bunch of routers using a shared medium. A common
> scenario would be a set of 4 routers, for instance a pair of border
> routers and a pair of core routers. I'd like either a full-mesh or
> circle topology. Putting all nodes in a /29 isn't ideal because of the
> DR/BDR/etc stuff. I want all nodes and links to be treated equally.
> Using point-to-multipoint sounds like a decent solution. I can configure
> several sessions on a single link without interference, up to the point
> where the circle is created. Like this:
>
> A - B
> |   |
> D - C
>
> However, if I try to add a link between A and C, things start to go not
> as expected. A already has 192.168.255.2/31 (towards B) and
> 192.168.255.4/31 (towards D) configured. If I add 192.168.255.10/31
> (towards C) and 192.168.255.11/31 on C (towards A), A and C can't ping
> each other using those addresses. This is because A will announce
> 192.168.255.10/32 throughout the area and thus "overriding" the
> 192.168.255.10/31 route on C (traffic will would be sent to either B or
> D, and not directly to A).
>
> What would be the cleanest solution for this?

FTR, the solution I'm currently testing with is using:

ip address add 192.168.255.10 peer 192.168.255.11 dev eth1

instead of:

ip address add 192.168.255.10/31 dev eth1

Seems to work fine so far, but suggestions/comments/etc are still more 
than welcome.

Regards,
Ruben