BGP-RIB FAILURE

[amit_pahuja]

ello,

Here is the topology. I have eBGP ( AD20) between R1-ISP1 and R2-ISP.2

Between R1 and R2 i have iBGP as well as OSPF. Both R1 and R2 are receiving all MPLS routes from their respective PE routers.

But only R2 is installing in the routing table and R1 is showing as RIB failure. 

Can anyone help me to understand why there is RIB failure on R1 when it is receiving the routes from PE with AD as 20 ( as it is eBGP)?

MPLS ISP-1                                   MPLS ISP-2

|                                                        |

|                                                        | 

R1 ----------------------------R2

[Meheretab Mengistu]

Hi,

You will get BGP-RIB failure when you have a better route learned and added to the RIB.

Please share with us the output of show ip bgp and show ip route from both R1 and R2.

HTH,

Meheretab

[Jaderson Pessoa · Accepted solution]

It just means the route got to the routing table via some other protocol (static, or other dynamic with lower AD).



Remember that each protocol has it's election (best path) and hands the best unique results to the routing table. Then the routing table has it's election (AD) and keeps only the best unique paths among ALL protocols.



Do a "show ip route #.#.#.#" where the #'s are a route that shows a RIB Failure.

https://learningnetwork.cisco.com/thread/32683

[amit_pahuja]

Thanks Jaderson for your reply...

I think you are right....all external routes R1 is learning from its PE via eBGP as well as from R2 via iBGP. R1 chooses the one from R2 as the best BGP route based on the BGP route selection process ( in my case Local Preference was the tie breaker), AD is not considered here.Then it compares that iBGP route with OSPF learned route ( again from R2) and now chooses OSPF ( as it has better AD of 110 than iBGP 200) and installs in the routing table... Correct me if i am wrong...

Thanks Jaderson and Jon for your help...

Now my another question is : Is it OK to have iBGP and OSPF both between R1 and R2. 

WAN is active-standby...FYI

[Jaderson Pessoa]

Yes this is correct behavior in this case. There is no problem running IBGP and OSPF, just work to do not provide routing looping in your environment.

Thats it :)

[Jaderson Pessoa]

Please, rate all port that were helped you and mark as solved. This will help other people with the same doubt or issue.

[Jon Marshall]

Are you redistributing BGP routes into OSPF ? 

Jon

[amit_pahuja]

Yes Jon, BGP is being redistributed into OSPF...

Also, there is no static route configuration or route manipulation with less AD than eBGP(AD-20).

[Jaderson Pessoa]

please, provide output below;

show ip route
show ip bgp

mark what route you want see on the RIB.

[Jon Marshall]

Sorry, I should also have asked is OSPF being redistributed into BGP as well. 

If it is then I am pretty sure I know what is happening. 

Jon

[amit_pahuja]

No JON, OSPF is not being redistributed into BGP... BGP is advertising the internal networks via network statements