I am looking at shortest path tree switchover...and got a question.
When the leaf router (router clostest to the receiver) gets its S,G entry finally and forwards the multicast packets it will try to switchover and make a shortest path tree to the source.
So far so good.
The leaf router sends a join message towards the first hop router instead of the RP. And when it comes to the point where there is a router in the chain that has a different interface pointing to the source than to the RP, this router will send the join message to the source of the multicast stream and a prune to the RP (so that the way to the RP is not used anylonger).
But what happens with the routers that already have a source tree from the first hop router to the RP. How do they get the prune?
Thanks in advance!