[PATCH 0/4] BGP unnumbered automatic peering based on IPv6 ND

[Ondrej Zajicek]

On Fri, Dec 05, 2025 at 02:52:28PM +0100, Matteo Perin via Bird-users wrote:
> Dear BIRD dev-team and community,
> 
> This is a patch proposal spawned from the discussion in a previous mailing list thread [0], regarding how to achieve automatic BGP peering establishment using the IPv6 Neighbor Discovery mechanism.
> 
> Over the last few weeks, I worked on implementing the feature with the outline Maria Matejka kindly provided.
> As expected, it proved to be quite challenging, especially when it came to integrate the peer discovery approach with the current dynamic BGP implementation.

Hi

Thanks for the patches. From cursory reading these patches look good.
I have several comments:

- I think that peer net_addr schould contain interface (in the form of
interface id). That would eliminate need for 'from' option in BGP and
also simplify config in case of link-local neighbors on multiple
interfaces.

Alternatively, one could consider sending interface as a route attribute
(like in next hop attribute for regular IP routes) but i think in this
case having it as a part of net_addr would make more sense.

- peer channel in BGP should be regular struct channel (like MPLS
channel) and not struct bgp_channel. This is for channels that are also
AFI/SAFI on the BGP session. 'from' option is not necessary as above,
'persist' option could be BGP option.

- It seems to me that option 'neighbor discovery' should be called more
like 'router discovery' to avoid confusion with detecting regular IP
neighbors by listening to Neighbor Discovery messages.

- I would consider to set pxlen for peer_net_addr as 0 in the secne that
the field is unused.

-- 
Elen sila lumenn' omentielvo

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