[j-nsp] JUNOS resolves indirect next-hops using other BGP routes

[Pekka Savola]

On Wed, 4 Feb 2009, Tore Anderson wrote:
> * david.roy at orange-ftgroup.com
>> The protocol next-hop seems to be resolvable : but it is not directly
>> known in our IGP. So you have a recursive lookup til you find a
>> forwarding next-hop.
>
> Yes, exactly.  What surprises me, however, is that EGP routes is
> considered at all when resolving indirect next-hops of iBGP routes.  I
> have problems coming up with a scenario where that behaviour would be
> desireable, and the JUNOS documentation I quoted is also quite clear on
> the fact that it is intra-AS OSPF, IS-IS, RIP, or static routes that are
> supposed be used for next-hop resolving.
>
> The behaviour I expect (and want) is for routes that come with a
> next-hop that is not resolvable through my IGP should be ignored
> outright and _not_ be placed in the PFE, even though the next-hop is
> resolvable using a BGP route.

This is a feature.  Why should BGP next-hop resolution not be able to 
use BGP routes?  There could be more specifics that give the right 
information.

You can adjust the route resolution policy with 'routing-options 
resolution rib inetX-X import FOO'.  That's what we do to exclude e.g. 
our default discard route from affecting nexthop feasibility 
algorithm.

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings