OSPFv2 and unnumbered interfaces without peer ?

[Ondrej Zajicek]

On Sun, Jan 24, 2021 at 11:57:36AM -0500, Etienne Champetier wrote:
> Hi All,
> 
> Is it possible to use unnumbered interfaces without having a peer
> address setup ?
> Without a peer the state stays 'PtP (stub)'
> 
> Jason (in CC) and I were wondering if this is a Bird limitation or if
> having a peer setup is really important semantically (and worth adding
> to all protocols in OpenWrt)?

Hi

It is not possible in BIRD, but it is an implementation limitation, where
BIRD OSPF implementation is strongly coupled with address slots instead
of real interfaces. You can have multiple OSPF 'interfaces' (for each
address slot) associated with one real (OS) interface and incoming
packets are dispatched based of source addresses.

The semantic advantage is that gateway addresses for such routes are
considered local (based on interface addresses) so you do not need
ONLINK flag. For true PtP link you can use routes without gateway,
but often PtP links are just ethernet.


> https://github.com/openwrt/openwrt/pull/3810

Well, peer address network setup is useful anyways.

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
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"To err is human -- to blame it on a computer is even more so."