[Xorp-users] IPv6 & BGP

[Kristian Larsson]

I apologize for not responding to this earlier.

On Sat, Dec 17, 2005 at 09:09:33PM +0200, Hasso Tepper wrote:
> Atanu Ghosh wrote:
> > >>>>> "Hasso" == Hasso Tepper <hasso@linux.ee> writes:
> > Actually this is not a protocol issue but a configuration issue. In the
> > configuration we have an IPv4 nexthop marked as a mandatory item. In
> > the case where you want to use BGP for IPv6 only we have no way of
> > disabling the check (yet).
> 
> The need to specify next-hop explicitly in the configuration even in the 
> IPv4 case is very strange requirement IMHO. Never seen it in any other 
> implementation. The address used in NEXT_HOP attribute should be normally 
> derived from interface address used for BGP session (local-ip in XORP). 
> 5.1.3 section in draft-ietf-idr-bgp4-26 should give quite good rules for 
> that. In case there is need to disregard these rules, modifying nexthop 
> is job of policies.
Indeed it is strange.
> 
> > If you set the ipv4-unicast and ipv4-multicast flags to false and you 
> > have no local IPv4 addresses then just choose a legal IPv4 address. The 
> > IPv4 nexthop address should *not* be used it just needs to satisify the 
> > configuration constraint. I have never tried an IPv6 peering on a 
> > machine that does not have any IPv4 addresses configured but I would 
> > expect it to work. 
> 
> Note, that there is still need to have the IPv4 unicast address in the BGP 
> speaker. Even RFC2858bis states:
> 
> "This document assumes that any BGP speaker (including the one that 
> supports multiprotocol capabilities defined in this document) has to have 
> an IPv4 address (which will be used, among other things, in the 
> AGGREGATOR attribute)."
> 
> And the router id MUST be valid IPv4 unicast address as well.
The router id I can live with but do I really need
v4 for anything else?

After sending the mail I got it working - I had
forgotten the local-ip variable.
However there's still a bug here. When missing
next-hop xorp will provie a clean error message
however this was not the case with local-ip. I 
just got some mumbo-jumbo.
The router is now operational and thus I cannot
debug anymore with it. I intend to setup a similar
scenario when I have the time but this should be
pretty easy to debug..
edit protocols bgp
create bgp-id 1.3.3.7
create local-as 1337
edit peer 2001::1:3:3:7
set as 1338
commit  (will generate a clean error - lack of
next-hop I beleive)
set next-hop 1.3.3.7
commit  (will genereate mumbo jumbo if I remember
correctly)

For the intersted this router is now announcing
2001:4db8::/32 :)

   Kristian.