[j-nsp] MX204 and IPv6 BGP announcements

[Lee Starnes]

Thanks Mark for the quick reply. That was the validation I was looking for.
The TAC tech was really unsure about what he was doing and I had to guide
him through things, So this is very helpful.

Thanks again.

-Lee


On Tue, Feb 6, 2024 at 8:54 AM Mark Tinka <mark at tinka.africa> wrote:

>
>
> On 2/6/24 18:48, Lee Starnes via juniper-nsp wrote:
>
> > Hello everyone,
> >
> > I was having difficulty in getting an announcement of a IPv6 /32 block
> > using prefix-lists rather than redistribution of the IP addresses in from
> > other protocols. We only have a couple /64 blocks in use at the moment
> but
> > want to be able to announce the entire /32. In cisco, that would just be
> a
> > holddown route and then announce. Not sure how it works to Juniper.
> >
> > I configured a prefix-list that contained the /32 block in it. Then
> created
> > a policy statement with term 1 from prefix-list <list> and then term 2
> then
> > accept. Set the export in BGP protocol peer of this policy statement and
> it
> > just ignores it.
> >
> > Now this same setup in IPv4 works fine.
> >
> > After a week of going round and round with Juniper TAC, they had me
> setup a
> > rib inet6 aggregate entry for the /32 and then use that in the policy
> > statement.
>
> This is the equivalent of the "hold-down" route you refer to in
> Cisco-land. Useful if the route does not exist in the RIB from any other
> source.
>
> I'm guessing your IPv4 route just works without a hold-down route
> because it is being learned from somewhere else (perhaps your IGP, iBGP
> or a static route), and as such, already exists in the router's RIB for
> your export policy to pick it up with no additional fiddling.
>
> Typically, BGP will not originate a route to its neighbors unless it
> already exists in the routing table through some source. If it is an
> aggregate route, a hold-down pointing to "discard" (Null0 in Cisco) is
> enough. If it is a longer route assigned to a customer, that route
> pointing to the customer will do.
>
> Mark.
>