Routing table not updating automatically

[Mark1110]

Hello,

We have two cisco routers R1 and R2 at two data centers. One is primary R1 and second is for redundancy R2.  we are using ospf to share routes between datacenters. for connectivity with client sharing routes via BGP. for auto failover, put BGP AD 130 at redundant site R2. because sharing routes via ospf AD 110. but when we do failover test, routing table not updating automatically. i have to do clear ip route to update routing table. any one know reason and solution?

I am using redistribution of BGP via ospf on both side. Let me explain with an example.

I am learning 1.1.1.1/24 route from client via BGP on both location R1 and R2.

That route is share via ospf between two location. Location R2 has AD for bgp 130. that's why it choose ospf path from R1 location instead of client bgp path at R2.

now, if i shutdown primary R1 bgp connection with client. 1.1.1.1/24 is taking correct path. BGP at R2 and ospf from R2 at R1. 

Problem is when I turn on bgp connection at primary R1, Routing table not updating to learn BGP route at R1 and ospf from R1 at R2. I have to do clear ip route to make it work. 

Thanks,

Mark

[Jon Marshall]

Few more details would help ie. are you doing one way or mutual distribution, what is meant to happen, what do you see in routing table etc. 

Jon

[Mark1110]

I am using redistribution of BGP via ospf on both side. Let me explain with an example.

I am learning 1.1.1.1/24 route from client via BGP on both location R1 and R2.

That route is share via ospf between two location. Location R2 has AD for bgp 130. that's why it choose ospf path from R1 location instead of client bgp path at R2.

now, if i shutdown primary R1 bgp connection with client. 1.1.1.1/24 is taking correct path. BGP at R2 and ospf from R2 at R1. 

Problem is when I turn on bgp connection at primary R1, Routing table not updating to learn BGP route at R1 and ospf from R1 at R2. I have to do clear ip route to make it work. 

[Jon Marshall]

Are you redistributing OSPF into BGP as well ? 

Jon

[Mark1110]

yes Jon.

[Jon Marshall · Accepted solution]

Then it is probably this that is happening - 

https://community.cisco.com/t5/routing/nx-os-9000-ebgp-failover-help/td-p/4152395

apologies but rather than type it all out again it is easier to link to where I have described it before. 

Jon

[MHM Cisco World]

https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/213285-understand-the-importance-of-bgp-weight.html

[Jon Marshall]

Didn't know Cisco had a document for this, thanks for posting. 

Jon

[MHM Cisco World]

You are so so Welcome @Jon Marshall 

[Mark1110]

Thank you @Jon Marshall  and @MHM Cisco World . I applied it and its working correct now