The main Makefile rules directly compile to object files;
this target is only for debug purposes.

Which, in contrast to SAFI 128, does not use MPLS labels.

When recursive routes with hybrid next hops (e.g. IPv6 route with IPv4 next
hop) are allowed, we need both IPv4 and IPv6 IGP tables.

This avoids collisions with non-BIRD routes in kernel tables.

Covers IPv4/VPNv4 routes with IPv6 next hop (RFC 5549), IPv6 routes with
IPv4 next hop (RFC 4798) and VPNv6 routes with IPv4 next hop (RFC 4659).
Unfortunately it also makes next hop hooks more messy.

Each BGP channel now could have two IGP tables, one for IPv4 next hops,
the other for IPv6 next hops.

Basic support for SAFI 4 and 128 (MPLS labeled IP and VPN) for IPv4 and
IPv6. Should work for route reflector, but does not properly handle
originating routes with next hop self.

Based on patches from Jan Matejka.

BTW, 'prefices' is hypercorrection, as 'prefix' is from 'praefixum' with
plural 'praefixa'.

The patch fixes several bugs introduced in previous changes, simplifies
the protocol by handing routes uniformly, introduces asynchronous route
processing to avoid issues with separate notifications for each next-hop
in ECMP routes, and makes reconfiguration faster by avoiding quadratic
complexity.

It took too much time to analyze what's the meaning of nhu_state values
so I spent less than the same amount of time documenting it.

Thanks to Vincent Bernat for the patch.

Mostly capability signalling