[afnog] route in rib, not in fib - why?

[Philip Smith]

Hi Frank,

Ah yes, this one... And the next hop for these 60 routes is? ;-)

Make sure the iBGP on their IX peering router has "neighbor x.x.x.x 
next-hop-self" configured. In fact, just do this on all iBGP speaking 
routers, its industry best practice. (That's a note to all list readers. 
;-))

BGP will only put prefixes into the routing table (ie RIB) if they are 
valid paths and there is no better path known via another routing 
protocol. And the common cause of it not doing this is that the next-hop 
is unreachable (ie not in the RIB). Next-hop for the IXP prefixes will 
be the IX LAN, and the IX LAN is probably not in their IGP (and it 
shouldn't be!), so you need to fix the next-hop so that it is the 
address of their IX router.

If it is not the above, then as Mark said, a "show ip bgp" will tell all.

philip
--

Frank Habicht said the following on 24/6/08 19:44:
> Hi all,
> 
> new peer at our IX has this prob:
> at border router to uplink, they get the ~60 routes from iBGP from their 
> other router (at IXP place) correctly.
> 
> "show ip bgp" shows them (sorry for old syntax - dont have their "show 
> version " (yet)).
> 
> but (!):
>  "show ip route" does only show the 4 connected and static routes
> :-(
> What could be wrong?
> 
> and that (show ip route) is also how the packets behave.
> 
> I hope the subject summarises correctly.
> 
> Sorry to be very vendor C specific ;-)
> let me know if you need more info.
> (but the box isnt under my control)
> 
> Frank
> 
> snippets from config:
> 
> version 12.4
> 
> interface FastEthernet0/1
>  description ...............
>  bandwidth 512
>  ip address 192.168.x.161 255.255.255.252 secondary
>  ip address n.n.n.n m.m.m.m
>  duplex auto
>  speed auto
> !
> router bgp <priv-ASN>
>  no synchronization
>  no bgp log-neighbor-changes
>  network s.o.m.e mask n.e.t.224
>  neighbor 192.168.x.162 remote-as <priv-ASN>
>  neighbor 192.168.x.162 soft-reconfiguration inbound
>  no auto-summary
> !
> ip classless
> ip route ................
> 
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