BIRD <-> Quagga OSPF Compatibility

[Ondrej Zajicek]

On Wed, Nov 02, 2011 at 02:08:29PM +0100, Joakim Tjernlund wrote:
> >
> > --On 2 November 2011 13:02:13 +0100 Ondrej Zajicek <santiago at crfreenet.org>
> > wrote:
> >
> > > The patch is OK (as a workaround). Note that the problem is only
> > > related to 'unnumbered' ptp links, so the simplest workaround
> > > is just to assign (at least /30) regular IP prefix to that link.
> > > I am not strongly opposed to add such kind of broken-quagga-compat
> > > option, but not sure if it is worth if it is only related to
> > > such corner cases.
> >
> > I am guessing this might be one of the issues affecting us (*). We
> > can't do numbering as we have large numbers of /32s as interface
> > routes. Numbering these would use either 2 or 4 times the address
> > space which is not acceptable.

I forgot, not everyone uses private addresses :-), It seems that using
/31 quasi-reqular prefix (RFC 3021) is probably also OK.

> What if you forcefully remove the IA_PEER flag for your ppp interfaces?
> Then an IP address is send instead of ifIndex in the router LSA. Could be an useful
> addition to bird.

IA_PEER is not a flag of iface, it is internal BIRD flag (of an address)
signalizing that there is not a common prefix (it is 'unnumbered').
So it is not possible to forcibly remove that (outside of BIRD).

You perhaps mean IFF_POINTOPOINT system iface flag. Forcibly removing
it from physically ptp ifaces (like ppp or slip) is not a good idea as
in that case BIRD would think that these ifaces are physically NBMA and
does not allow run OSPF in PTP mode on it (just NBMA or PTMP mode). It
would be possible to run BIRD in PTMP mode on unnumbered iface over
physically PTP link (PTMP and PTP mode is very similar) but it is
non-standard (RFC implicitly supposes that PTMP is numbered) so it is
probably not a good starting point for BIRD-Quagga compatibility (i
don't have a clue whether and how PTMP mode is implemented in Quagga).

-- 
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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