Question 220
A customer eBGP peer uses a loopback address instead of its physical interface. Observed: The BGP session cannot form across the connected transport. Which change-acceptance control is most relevant to preventing this exact failure?
Explanation
Correct Answer
The control is specific to the initial failure. It requires the result The loopback peering establishes over the approved routed path. and treats The BGP session cannot form across the connected transport. as a failure signal. The causal concern is the multi-hop ebgp transport and update-source configuration are incomplete.
Incorrect Answers
It is valid for another service scenario but checks some nonclient speakers still cannot learn routes from other nonclients. This case instead needs a gate for the bgp session cannot form across the connected transport and evidence that the loopback peering establishes over the approved routed path.
The proposed control is tied to import policy assigns the backup a higher preference or local preference, typically observed when backup path is preferred when an origin prefix first appears. Here the target is the multi-hop ebgp transport and update-source configuration are incomplete; monitor the loopback peering establishes over the approved routed path.
This gate monitors a different failure, the routing table grows beyond contracted limits after a misconfiguration. It would not detect the current problem: The BGP session cannot form across the connected transport. The appropriate check requires the loopback peering establishes over the approved routed path.