Unnumbered PtP links (Was: Re: OSPF: incorrect path computation for v2.0.5+?)

[Ondrej Zajicek]

On Tue, May 26, 2020 at 07:58:57AM +0000, Kenth Eriksson wrote:
> On Mon, 2020-05-25 at 23:04 +0200, Ondrej Zajicek wrote:
> > > Haven't actually tested if this actually interops with bird.
> > > 
> > > The RFC states that unnumbered ptp links shall use ifIndex, whereas as
> > > numbered ptp links shall use IP interface address. Any reason to not
> > > follow the RFC?
> > 
> > Well, i generally prefer not to make intentional changes that break
> > existing setups, and switching to this (as done by the patch i sent)
> > would break Mikrotik compatibility for unnumbered PtP links (due to
> > Mikrotik broken SPF calculation).
> > 
> Not sure I agree the alternative is better. Violating standard to
> maintain interoperability with a broken Mikrotik implementation. That
> only makes sense if the Mikrotik way of doing it was de facto standard.
> If not, drop compatibility.

Well, we will change it during next major release, while keeping
compatibility during minor releases. The latest patch also allow to
control it as a per-interface setting.

> > > Ondrej, what are you plans for the patch provided? Good to go for
> > > master?
> > 
> > Seems to me that perhaps the least painful solution is to use 2.0.4
> > approach (position based) for regular OSPF, and switch to ifIndex/data
> > based approach (like the patch) when OSPF graceful restart is enabled.
> 
> So does that mean that there is a bird interop issue for nodes running
> with and without GR activated? 

No, this is a local issue for each node, it should not lead to
interoperability issues with BIRD on different setting or with
different implementations.

> > So plan is to make a new/different patch for master.

Made a new patch that went to master, could you try it?

https://gitlab.labs.nic.cz/labs/bird/-/commit/c1632ad0f39f7221d649a9e469cacc38105528e2

-- 
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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