Hello. There are users out there who do desperately want multipath routing support in Bird. Please don't just ignore the need for multipath. Regards, Andy. Securepoint user. -----Original Message----- From: owner-bird-users@atrey.karlin.mff.cuni.cz [mailto:owner-bird-users@atrey.karlin.mff.cuni.cz] On Behalf Of Joakim Tjernlund Sent: 26 April 2010 00:05 To: Ondrej Zajicek Cc: bird-users@trubka.network.cz Subject: Re: OSPF performance/SPF calculations Ondrej Zajicek <santiago@crfreenet.org> wrote on 2010/04/25 23:20:33:
On Sun, Apr 25, 2010 at 06:08:04PM +0200, Joakim Tjernlund wrote:
This is not a problem because both SPF and calc_next_hop() chooses the cheapest (full) ptp link. They both uses the same (local) metrics.
Our ptp links typically have the same cost between the same two routers so it is not unlikely that the link will be asymentric I think. However I don't think that will be a problem anymore as BIRD don't use/support equal cost multipath, right?
Yes.
Right, how about these statements from RFC 2328: ... These talk about inheriting ALL next hops from the parent and I don't see the BIRD does that. Looks like BIRD just selects one next hop from its parent? Assuming it is, does that impose any restricts?
Yes, BIRD chooses one next hop. Because BIRD does not implement equal cost multipath, this is not a problem.
Some other random questions:
One think I always wanted is the possibility to add an host IP address to all areas, in my case I like to export the routers primary IP address to all areas so the router can always be reached. Is that possible with BIRD?
You can use 'stubnet' option to add 'virtual' stub network (in that case /32 stub) to the router-LSA. You can add this option to each area config to get this in each area.
That sounds exactly as what I need, thanks.
Or add /32 stub network to one area, other areas get a summary-LSA with that address.
If you pull the cable to an ethernet I/F that is currently in a OSPF domain, do BIRD delete the whole subnet from the R-LSA or do you leave a host route with the I/F's IP address in the R-LSA?
BIRD does not use link availability information, therefore if you pull the cable, BIRD keeps the whole subnet in the router-LSA (if it is a stub network).
If you do(any plans?), my vote is to leave a host stub in the R-LSA as it may very well be possible to reach that IP address over another link. Jocke Monitor Computer Systems Limited Company Registration Number: NI 17805 Registered Office: 3 Pine Crest, Holywood, North Down, Northern Ireland BT18 9ED