When using PIM-SM in ASM mode, which two events trigger the creation of a shortest-path tree?
(Choose two.)
A.
Multicast traffic received at the receiver’s designated router (DR).
B.
PIM join received at the receiver’s designated router (DR).
C.
PIM join received at the source designated router (DR).
D.
PIM registers received by the rendezvous point (RP).
Only A is needed to initiate the SPT.
However I think C is correct instead of D as there is no such thing like PIM register messages and PIM join is forwarded to source as an action after A.
I think you are right Mike.
Multicast traffic received at the receiver’s designated router and then (S,G) join is being sent up to source’s DR and we have SPT created.
Nah, you are wrong and I was wrong 🙂
Answer is correct.
When RP receives PIM register message (encapsulated by source DR multicast packet as unicast to RP), TP sends (S,G) towards source in order to create an SPT.
So, A and D are correct triggers for creation of SPT.
TP is typo – should be RP.
Seems C and and D are the correct answers based on this link http://www.juniper.net/documentation/en_US/junos13.2/topics/concept/multicast-pim-sparse-mode-registration.html