What mechanism does PIM use to forward multicast traffic?
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A. B. C. D.A.
PIM (Protocol Independent Multicast) is a multicast routing protocol used to forward multicast traffic across a network. PIM relies on a multicast distribution tree (MDT) to forward traffic to receivers that have expressed an interest in receiving the traffic.
PIM supports two modes of operation: Dense mode (PIM-DM) and Sparse mode (PIM-SM). The mode used depends on the size and density of the multicast group and network topology.
In PIM-SM, the multicast traffic is forwarded using a pull model, where the receivers explicitly request the multicast traffic by sending join messages towards the RP (Rendezvous Point). The RP is a designated router that acts as a meeting point for the sources and receivers of a multicast group. When the RP receives a join message from a receiver, it sends a join message towards the source, and the source starts forwarding the multicast traffic towards the RP. The RP then forwards the multicast traffic to the receiver. This mechanism allows PIM-SM to conserve network resources by only forwarding traffic to those receivers that have explicitly requested it.
In contrast, PIM-DM uses a push model to deliver multicast traffic. In PIM-DM, routers flood multicast traffic to all interfaces within a network, except for the interface it was received on. Each router receiving the multicast traffic forwards it to all of its interfaces, except for the interface it was received on. This mechanism is called dense because it floods the network with multicast traffic, even if there are no interested receivers, which can result in a high volume of unnecessary traffic.
Therefore, the correct answer to the question is A. PIM sparse mode uses a pull model to deliver multicast traffic. In PIM-SM, multicast traffic is only forwarded to those receivers that have requested it, allowing PIM-SM to conserve network resources and reduce unnecessary traffic.