Handling IPv6 BGP routes with :: next-hop

[Chriztoffer Hansen]

On Tue, 3 Aug 2021 at 09:13, Alexander Shikov <a.shikov at dtel-ix.net> wrote:
> The first (best) route has next-hop '::' and routers of some of our customers
> started dropping BGP sessions with 'Invalid next-hop' cause.
>
> I dumped packets coming from customer 2001:7f8:63::f2 and it is really sending next-hop
> as '::'.
>
> I enabled logging of 'gw' and 'from' route attributes for net 2a09:8387:ffff::/48,
> and I got the following:
>
> Aug  3 09:57:10 <daemon.info> rs1 bird6: DEBUG: gw:2001:7f8:63::f4 ---- from:2001:7f8:63::f4
> Aug  3 09:57:10 <daemon.info> rs1 bird6: DEBUG: gw:2001:7f8:63::69 ---- from:2001:7f8:63::69
> Aug  3 09:57:11 <daemon.info> rs1 bird6: DEBUG: gw:2001:7f8:63::f2 ---- from:2001:7f8:63::f2
> Aug  3 09:57:12 <daemon.info> rs1 bird6: DEBUG: gw:2001:7f8:63::60 ---- from:2001:7f8:63::60
>
> Thus 'gw' and 'from' variables both contain IPv6 address of the peer.
> But shouldn't 'gw' contain '::'?

Do you know what equipment the customer uses? (e.g. reverse lookup the
IPv6 LL EUI-64 (*ff:fe*) of the customers' equipment and map the MAC
to an OUI)

Might be a configuration error on the customer side that the gw is not
set with both an IPv6 and IPv6 LL address.