Rib-Failure

[hemant.kmr22]

Hi All

R1-------GW--------R2

Here I am running ospf as IGP and advertising 10.2.0.0 via ospf as well as OSPF

and got this rib failure for 10.2.0.0

GW#show ip bgp ¦ include r>
r>10.2.0.0/16 10.0.1.2 0 0 65001 i

A more thorough investigation of the BGP entry does not give you a lot of additional information:

GW#show ip bgp 10.2.0.0
BGP routing table entry for 10.2.0.0/16, version 7
Paths: (1 available, best #1, table Default-IP-Routing-Table, RIB-failure(17))
Flag: 0x820
  Advertised to update-groups:
        1    2
  65001
    10.0.1.2 from 10.0.1.2 (10.0.1.2)
      Origin IGP, metric 0, localpref 100, valid, external, best

I

I  CHECKED ON INTERNET ABOUT RIB-FAILURE I SAID THIS COULD BE BECAUSE OF LOWER AD VALUE BUT WHAT DOES BGP HAVE WITH IT

ALL BGP REQUIRE IS A IGP OR STATIC CONNECTION IN ROUTING TABLE FOR NEIGHBOR PEERSHIP

MOREOVER I AM NOT RUNNING ANY STATIC ROUTES

ANY CLUES

THANKS IN ADVANCE

HEMANT KUMAR

[Peter Paluch]

Hemant,

What BGP is telling you here is that it tried to insert the network 10.2.0.0/16 into the RIB (the main routing table) but it could not do it because the network was already present there with a lower Administrative Distance than what the BGP uses. Therefore, the BGP-learned 10.2.0.0/16 was considered to be less trustworthy and was not installed into the RIB.

I believe you have indicated yourself that the network is advertised both by OSPF and BGP. In that case, if you are running iBGP, the OSPF-learned 10.2.0.0/16 has the AD of 110 while the iBGP-learned 10.2.0.0/16 has the AD of 200. Thus, OSPF wins and BGP is denied installing the network 10.2.0.0/16 into the routing table. This is what is called the RIB-Failure.

Best regards,

Peter

[hemant.kmr22]

Hi Peter

You mean to say the if any route learned via protocol having AD value less then IBGP(200) will not be installed ?

i am not able to understand because my route to R3 is also learned via OSPF and BGP but it is installed into BGP table

CAN ANY ONE EXPLANE ME WHY BGP REQUIRE IGP ROUTE IN IT'S IGP TABLE BEFORE INSTALLING IT INTO BGP TABLE

AND WHAT WOULD BE THE EFFECT ON BGP IF THAT ROUTE IS ALSO LEARNED VIA STATIC ROUTE

TONS OF THANKS IN ADVANCE

Hemant Kumar

[minumathur]

Hi Hemant

if you check your routing table then you already have IGP route for destination,so that why it create RIB-failure. if you check BGP FAQ docs in cisco.com. you will get your answer

What does r RIB-Failure mean in the show ip bgp command output?

R1> show ip bgp
BGP table version is 5, local router ID is 200.200.200.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
r> 6.6.6.0/24       10.10.13.3               0    130      0 30 i
*> 7.7.7.0/24       10.10.13.3               0    125      0 30 i

A. 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.