bird's not forwarding point-to-point routes via OSPF

[Noel Burton-Krahn]

Thanks Ondrej,

In our case, we're assigning peer point-to-point addresses on veth
interfaces that we use for LXC containers.  So they're essentially mini
subnets with two interfaces.  I didn't expect bird to treat peer addresses
differently, so it took a few hours to figure out exactly what the problem
was and how to work around it.  So, I'd vote for either always allowing
peer addresses, or adding a configuration option to make that behaviour
more explicit.  We'll work around that for now by adding a second /32 IP
address to each interface.


Cheers,
--
Noel




On Thu, Oct 16, 2014 at 7:42 AM, Ondrej Zajicek <santiago at crfreenet.org>
wrote:

> On Wed, Oct 15, 2014 at 11:00:03AM -0700, Noel Burton-Krahn wrote:
> > Is there something about point to point addresses that could keep bird
> > from forwarding them?  I'm assigning a point-to-point address to a
> > veth pair like so:
> >
> >     ip link add veth1 type veth peer name veth2
> >     ip addr add 10.0.0.1/32 peer 10.0.0.2/32 dev veth1
> >     ip addr add 10.0.0.2/32 peer 10.0.0.1/32 dev veth2
> >
> > Neither of those addresses get forwarded via OSPF to other hosts.
> > They *do* get forwarded if I add the addresses without a peer like
> > this:
> >
> >     ip addr add 10.0.0.1/32 dev veth1
> >
> > Now I've added the same address (10.0.0.1/32) to veth twice, and bird
> > is forwarding a route for that address to OSPF peers.
> >
> > Is there a way for bird to accept the "peer" address?  I tried "learn"
> > in the kernel but that didn't help.
>
> .. also ..
>
> On Fri, Oct 10, 2014 at 12:05:30PM +0200, Thomas Goldberg wrote:
> > Hello,
> >
> > we've OSPF running over a openvpn ptp tunnel and some problems with
> > the routes injected by bird (v1.4.5).
> ...
> > Shouldn't bird inject routes like this on the corresponding router
> > (without having to learn them via the direct protocol)?
> > 10.176.3.29/32 dev lo [o_internal 2014-10-09 00:00:00] * I (150/0)
> [10.176.3.29]
>
> Hello
>
> This is IMHO the same issue. It is an intentional behavior, BIRD does not
> inject local address for links with peer addresses, mainly based on idea
> that links with such addresses are just variants of 'unnumbered' ptp
> links and these addresses are just general 'loopback' addresses and are
> usually also used on other interfaces (like the explicit loopback
> interface) [*].
>
> Also note that it is usually simpler to add wanted addresses (using
> explicit loopback interface or using 'stubnet' option) in use cases where
> they should be propagated than remove unwanted addresses in use cases
> where they should not be propagated.
>
> But in retrospect i am not sure if this behavior was really a good idea.
> Perhaps automatic adding of host routes should be configurable and
> enabled by default for peer addresses to ensure that all addresses on
> OSPF-enabled interfaces are reachable in OSPF area.
>
> Any comments (esp. arguments for or against it) to this issue?
>
>
>
> [*] i.e. configuration like:
>
> ip addr add 10.0.0.1/32 dev lo / dummy0
> ip addr add 10.0.0.1/32 peer 10.0.0.2/32 dev eth0
> ip addr add 10.0.0.1/32 peer 10.0.0.3/32 dev eth1
> ip addr add 10.0.0.1/32 peer 10.0.0.4/32 dev eth2
>
> --
> 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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