Routers couldn't detect eBGP

[ss571]

Here is the current topology in GNS3:

There's a tunnel in between R3 & R4 for the iBGP, R3 & R5 are eBGP, R4 and R6 are eBGP. R1-R4 are within the OSPF AS 1190. The BGP works, R3 and R4 can detect the other BGPs shown here:

Below is the BGP output for R5 and R6:

And below is the ospf config in R1-R4:

However, R5 couldn't detect R6's AS and vice versa. I tried to ping from R3 to R4's f0/0 and R4 to R3's f0/0, it works, but when pinging R3 to R4's g1/0 and R4 to R3's g1/0, they failed. Then, when pinging from R5 to R3's f0/0 and R6 to R4's f0/0, it works but doesn't work when pinging R5 to R1's f0/0 and R6 to R2's f0/0. Here are the paths drawn out:

Does anyone know what might be the cause of this issue? 

[MHM Cisco World]

Did you config neighbor  ebgp multihop?

MHM

[Martin L]

Networks 148.91.0.0 and 148.92.0.0 must be in BGP either advertised or redistributed via connected interfaces. 

R5 and r6 cannot ping opposite gig1/0 IPs. You can even try ping r5 to r6 with source IP that is advertised. 

Regards, ML
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[Harold Ritter · Accepted solution]

Hi @ss571 ,

The issue is that the eBGP next hops are not known to R3 and R4 (148.92.0.2 is not known to R3 and next hop 148.91.0.2 is not known to R4).

You should add the following commands to R3 and R4:

R3:

neighbor 192.168.0.2 next-hop-self

R4:

neighbor 192.168.0.1 next-hop-self

Regards,

[ss571]

Thank you for the explanation sir, may I know which protocol do i put these commands under?

[Harold Ritter]

Hi @ss571 ,

They are

bgp

commands. They go under

router bgp 1190

Regards,

[ss571]

Thank you very much for everyone's assistance and advice, really appreciate all of your help 

[MHM Cisco World]

Ebgp work without ebgp multihop?

MHM

[Harold Ritter]

You are very welcome @ss571 and thanks for the feedback