When Pim asserts were sent over the LAN between R1 and R2. What metrics will be included? Only the WAN metric to the source or metric from the LAN interface to the source?
Section 3.6 of RFC4601 gives explains the exact scenarios in which the assert mechanism is needed in a sparse mode context.
>> 1. pim assert only works with PIM DM.
The title of the RFC is:
Protocol Independent Multicast-Sparse Mode (PIM-SM): Protocol
I would suggest you a quick read to it
Hope to help