Next-hop issue using iBGP

[Stefan Jakob]

Am 17.08.12 07:38, schrieb Dean Belev (Neterra NMT):
> Hi all,
> 
> I was performing a home lab and decided to test a new scenario including
> iBGP between a router and RS.
> That's a brief scheme of the lab:
> 
> ###
>                  5.5.5.1       5.5.5.2         6.6.6.100/24
>                           6.6.6.6/24                              
> 6.6.6.101/24
> Router3 (as3)---eBGP---> Router2 (as2)---iBGP/not a rs_client---> RS
> (as2)---eBGP / rs_client--- > Router1 (as1)
> 3.3.3.0/24                            2.2.2.0/24                       
>                                                                    
> 1.1.1.0/24
> ###
> 
> Since, as route 3.3.3.0/24 is seen in RS directly attached ( first asn
> is as3) with next-hop 6.6.6.100 (I've set the next-hop manually into the
> RS's config in bgp_in) I expect that Router1 should see it in the same
> way - with hext-hop 6.6.6.100.
> But the route is shown with next-hop 6.6.6.6 instead.  The first asn is
> as3 as expected.
> 
> Do you have any idea why the next-hop is not propagated from RS to R1 as
> present in the master table but changed to the local IP address ?
> I think its related with the "not a rs_client" relation between Router2
> and RS. Any idea how this behavior may be changed ?

It's always a good idea to provide the corresponding config.

Anyway, I guess  "gateway direct" in the bgp protocol definition on RS
for Router2 should do the trick.

Rgds, Stefan