Question 720
A BGP L2VPN service has duplicate site identifiers. Observed: Two attachments map to the same site ID and service endpoints conflict. Which ongoing validation gate would best detect a recurrence of this problem?
Explanation
Correct Answer
A useful regression gate tests whether the L2VPN forwarding map contains one consistent circuit per intended site and alerts when two attachments map to the same site ID and service endpoints conflict. This directly checks the technical weakness: Site-ID uniqueness is not maintained across the pseudowire service. The gate is derived from the fictional incident and is not an independent Juniper engineer signoff.
Incorrect Answers
The proposed control is tied to the reflector does not negotiate the l2vpn address family for that client, typically observed when a new spoke receives no Layer 2 VPN membership information. Here the target is site-id uniqueness is not maintained across the pseudowire service; monitor the L2VPN forwarding map contains one consistent circuit per intended site.
It is valid for another service scenario but checks each pe advertises a different esi for the same physical ethernet segment. This case instead needs a gate for two attachments map to the same site id and service endpoints conflict and evidence that the L2VPN forwarding map contains one consistent circuit per intended site.
This gate monitors a different failure, a newly connected pe advertises the service but never forwards bum frames when elected. It would not detect the current problem: Two attachments map to the same site ID and service endpoints conflict. The appropriate check requires the L2VPN forwarding map contains one consistent circuit per intended site.