[j-nsp] Generating routes from inactive/hidden contributors

[Chuck Anderson]

Last time I checked the contributing routes have to be in the
destination RIB for the aggregate/generate to go active.

On Sun, Mar 05, 2017 at 11:26:18AM +0000, Alexander Arseniev wrote:
> Hello,
> 
> Have You tried putting all routes from that peer in a routing-instance?
> 
> Then configure aggregate|generate in that instance and leak it into
> inet.0|whereever the other peers sit.
> 
> You can leak the whole table from that peer as well, but that
> amounts to 2x route memory consumption by that peer.
> 
> HTH
> 
> Thx
> 
> Alex
> 
> 
> On 03/03/2017 15:07, Tore Anderson wrote:
> >Hi,
> >
> >* adamv0025 at netconsultings.com
> >
> >>Interesting,
> >>There appears to be no cmd to override the default, "contributing route has
> >>to be active", requirement. (the "from state inactive" attachment point is
> >>only the export policy).
> >>I'm just thinking whether it's not working simply because the inactive
> >>routes wouldn't be advertised anyways -so why to bother aggregating them
> >>right?
> >True, but this is a generated route, not an aggregated route. They're
> >quite similar, but the generated routes can have next-hops (copied from
> >a contributing route), which means you don't really need the
> >contributing routes themselves to be active or even non-hidden to
> >actually forward packets somewhere useful.
> >
> >Aggregated routes are on the other hand discard only, so then you need
> >the more-specific contributing routes with their next-hops to avoid
> >blackholing traffic.
> >
> >(AIUI, anyway.)
> >
> >>But maybe if you enable "advertise-inactive" towards your iBGP -maybe
> >>then the aggregation starts to work?
> >Perhaps, but if both the generated route and its contributors are
> >indeed inactive in the RIB and thus not found in the FIB, then I don't
> >think the router would be able to forward the packets it attracts to
> >where it should.
> >
> >>Alternatively, I'm thinking of something along the lines of making the
> >>prefixes active (to allow the aggregate to be advertised), but use
> >>them only for routing not for forwarding -so that FIB on a local
> >>router is not skewed.
> >Yep, something like that would probably do the trick. I was hoping to
> >keep them out of the RIB in the first place though, to avoid having to
> >explicitly filter them on export to the FIB and iBGP peers, but maybe
> >there's no way around it.