I would like to clarify a question about Protocol Independent Multicast which operates in a Dense mode.
As stated by RFC 3973, PIM is a protocol which is used between the _routers_ in order to ensure multicast packets routing and forwarding in the network.
The same RFC states that hello messages are used in order to detect other PIM routers. When I captured the traffic between the host and a router I saw a number of hello messages that are destined as they should be to the address (18.104.22.168 - all PIMv2 routers) and which are going from the router interface which is a default gateway for the hosts in the LAN.
So, my question is failry simple - why router sends hello messages from that interface?
Is it like, that the router will send hello messages over all active ethernet interfaces even if there are no other routers connected to that particular interface?
I was just thinking, that underlying routing protocol such as OSPF will discover the neigbors and thus it is possible to know that there are no more active routers for that interface and thus no need of hello messages.
Just wondering, guys...