Protocol Independent Multicast
The Protocol Independent Multicast (PIM) tool is a routing protocol that is not beholden to any other existing protocols. This one actually works on top of existing unicast protocols so it doesn’t have to handle any unicast packets. In contrast, DVMRP does occasionally deal with unicast transmissions, such as tunneling and sending individual router probes.
There are two different flavors of PIM available. Each of these is refined to deal with a specific spread of group members. Specifically, the question to ask in choosing between these two options is whether your group members are spread out in a sparse manner or packed together in a dense one.
Protocol Independent Multicast-Sparse Mode (PIM-SM)
A sparse multicast ...
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