BGP attribute ext-next-hop

[Ondrej Zajicek]

On Tue, Apr 03, 2018 at 09:42:18AM +0000, Arvin Gan wrote:
> Hi all,
> 
>     The version of my bird is 2.0.0,  I found the source code of bird can support the attribute ext_next_hop for BGP, and this attribute is also parsed in cf-parse.y, but cannot found in user's guide document.
> Does anyone know  what configuration is coherent with the attribute ext_next_hop?  Is  the attribute ext_next_hop fully supported in version 2.0.0 ?

Hi

'extended next hop' is a BGP channel option, is fully supported in
version 2.0.2 (and likely also in 2.0.0 but i think there were some
bugfixes in this). Unfortunately we forgot to document it. Will fix that.
See doc/bird.conf.example2, where it is used (but commented out).

The option allows to use IPv4 next hop with IPv6 routes and vice versa.
For IPv4 channels, it requires that the peer announces the support by the
capability (RFC 5549). For IPv6 channels there is no relevant capability.
It can be used with all BGP channels with the exception of flowspec ones,
which do not have next hops anyways).

It is disabled by default, but perhaps we should change it to be enabled
by default for MPLS/VPNv6 channel (not sure what are expectations here).

-- 
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."