PIM Sparse Mode vs. PIM Dense Mode

C.

PIM (Protocol Independent Multicast) is a multicast routing protocol used to efficiently deliver multicast traffic over an IP network. PIM supports two modes of operation: PIM sparse mode (PIM-SM) and PIM dense mode (PIM-DM).

PIM Dense mode:

• In dense mode, all multicast traffic is flooded to all switches in the network, unless they explicitly opt-out.
• It assumes that multicast traffic is needed everywhere in the network, so it floods the multicast traffic to all interfaces.
• The initial multicast traffic is flooded to all interfaces, creating a shared distribution tree.
• As the switches receive the multicast traffic, they prune off branches of the tree where there are no interested receivers.
• PIM-DM is suitable for small, simple networks with low multicast traffic, where it is acceptable to flood multicast traffic across the entire network.

PIM Sparse mode:

• In sparse mode, multicast traffic is only sent to those parts of the network where there are interested receivers.
• Sparse mode assumes that multicast traffic is only required at specific parts of the network and only sends the traffic to those specific areas.
• It builds a distribution tree on-demand, by sending join messages upstream towards the source of the multicast traffic, as receivers request it.
• The source sends traffic down the tree to the interested receivers, and the routers prune the tree branches that no longer have receivers.
• PIM-SM is suitable for large, complex networks with high multicast traffic, where it is not acceptable to flood multicast traffic across the entire network.

Therefore, the correct answer is C. Sparse mode uses distribution trees. Dense mode floods.