You have configured MSDP peering between two autonomous systems that pass traffic between two sites, but the peering has failed to come up.
Which task do you perform to begin troubleshooting the problem?
Click on the arrows to vote for the correct answer
A. B. C. D.C.
The correct answer to begin troubleshooting the MSDP peering problem would be option C: Verify that both source interfaces are reachable from both peers.
Multicast Source Discovery Protocol (MSDP) is a protocol used for inter-domain multicast routing. It enables Rendezvous Point (RP) routers in different autonomous systems to share information about active sources of multicast groups. MSDP peers exchange source active advertisements (SA) to learn about active sources in each autonomous system. If the source is reachable and has active traffic, the MSDP peer creates a multicast forwarding state.
If the MSDP peering has failed to come up, it means that the MSDP peers are unable to exchange SA messages, and multicast traffic between the sites may not be reaching its intended destination. The problem could be due to various reasons, but the first step towards troubleshooting would be to verify the reachability of the source interfaces from both MSDP peers.
Option A, Verify that multicast has been disabled globally, is an unlikely cause for the MSDP peering problem because the MSDP protocol relies on multicast to exchange SA messages.
Option B, Verify that PIM-DM is configured on the source interface, is also an unlikely cause for the MSDP peering problem because MSDP does not depend on the multicast routing protocol being used to forward traffic.
Option D, Verify that the two MSDP peers allow asymmetric routing, is a good thing to verify but would be further down the list of troubleshooting steps because it is less likely to cause the MSDP peering problem compared to the reachability of source interfaces.
In summary, to troubleshoot a failed MSDP peering, the first step would be to verify that both source interfaces are reachable from both peers.