BGP rib-railure.

Unanswered Question
May 26th, 2009

hi ,

can any one help me with the link which give full details about RIB-FAILURES in bgp.

I have this problem too.
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guruprasadr Thu, 05/28/2009 - 00:24

HI Anil, [Pls RATE if HELPS]

Here is the Example with Sample (Masked) output:

The Network has IGP as OSPF and BGP also running.

The Remote Router receives Default-Information via OSPF and as well via BGP also. The Default-Information received via BGP is not preferred because Route with better administrative distance already present in IGP (OSPF).

In the Sample Output you can see 'RIB-failure(17))' on the SHOW output.

Router#sh ip bgp 0.0.0.0

BGP routing table entry for 0.0.0.0/0, version 17

Paths: (2 available, best #2, table Default-IP-Routing-Table, RIB-failure(17))

Advertised to update-groups:

3

Local

www.xxx.yyy.zzz (metric 141) from Route-Reflector_I (eee.fff.ggg.hhh)

Origin IGP, metric 0, localpref 100, valid, internal

Originator: www.xxx.yyy.zzz, Cluster list: 0.0.x.xxx

Local

aaa.bbb.ccc.ddd (metric 135) from Route-Reflector_II (iii.jjj.kkk.lll)

Origin IGP, metric 0, localpref 100, valid, internal, best

Originator: aaa.bbb.ccc.ddd, Cluster list: 0.0.x.xxx

Router#sh ip route 0.0.0.0

Routing entry for 0.0.0.0/0, supernet

Known via "ospf 100", distance 110, metric 1, candidate default path, type NSSA extern x, forward metric 50

Last update from mmm.nnn.ooo.ppp on GigabitEthernet0/1.xxx, 00:11:49 ago

Routing Descriptor Blocks:

* mmm.nnn.ooo.ppp, from qqq.rr.ss.tt, 00:11:49 ago, via GigabitEthernet0/1.xxx

Route metric is 1, traffic share count is 1

Router#sh ip route | i 0.0.0.0

Gateway of last resort is mmm.nnn.ooo.ppp to network 0.0.0.0

O*N2 0.0.0.0/0 [110/1] via mmm.nnn.ooo.ppp, 00:03:10, GigabitEthernet0/1.xxx

Hope I am Informative, Pls RATE if HELPS

Best Regards,

Guru Prasad R

anilraahi Thu, 05/28/2009 - 01:37

hi guru prasad,

i know the cause , plz provide me the solution. requirement is to prefer the BGP routes.

Regards

When BGP tries to install the bestpath prefix into Routing Information Base (RIB) (for example, the IP Routing table), RIB might reject the BGP route due to any of these reasons:

*

Route with better administrative distance already present in IGP. For example, if a static route already exists in IP Routing table.

*

Memory failure.

*

The number of routes in VPN routing/forwarding (VRF) exceeds the route-limit configured under the VRF instance.

In such cases, the prefixes that are rejected for these reasons are identified by r RIB Failure in the show ip bgp command output and are not advertised to the peers. This feature was first made available in Cisco IOS Software Release 12.2(08.05)T.

guruprasadr Thu, 05/28/2009 - 02:47

HI Anil,

One thing to remember is that each protocol has its own election process first. So in the example the same route learned from IGP AND iBGP, the BGP routing process has a slew of criteria for selecting the best path. ONLY the best paths from each individual routing protocol are passed to the routing table. Then (and ONLY then) does administrative distance come into play.

So when a particular route wins the BGP process, if it's an iBGP route, it will have a distance of 200. But you'll never see the same route from the same protocol with two different pieces of information there!

Best Regards,

Guru Prasad R.

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