Are you running ISIS? If your IGP is OSPF, then IBGP has nothing to do with ISIS or family iso for that matter.
Can you ping the remote BGP neighbor using as a source address the neighbor IP address configured on the IBGP peer?
Is port 179 blocked by firewall?
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If this worked for you please flag my post as an "Accepted Solution" so others can benefit. A kudo would be cool if you think I earned it.