Which of the following is not an assumption of PIM-DM?

Which of the following is not an assumption of PIM-DM?

• A. Each subnet has at least one interested receiver
• B. All data packets are sent to multicast addresses
• C. Packet forwarding is restored proactively
• D. Periodic flooding is avoided

Answer: (B)

The correct answer identifies that "All data packets are sent to multicast addresses" is not an assumption of Protocol Independent Multicast - Dense Mode (PIM-DM). In PIM-DM, multicast traffic is indeed primarily concerned with the efficient distribution of data using multicast addresses, but it does not necessarily assume that all data packets must be multicast. In PIM-DM, the assumption is that there are interested receivers on the network that will join the multicast group, and therefore data is sent to multicast addresses dictated by those group memberships. However, there can be other forms of traffic that do not utilize multicast at all, particularly in scenarios where there are no interested receivers or where certain network policies dictate unicast transmission. The other assumptions, such as each subnet having at least one interested receiver, packet forwarding being restored proactively, and the avoidance of periodic flooding, emphasize the operational characteristics of PIM-DM. Each subnet indeed must have at least one interested receiver for multicast traffic to be relevant. Proactive restoration of packet forwarding ensures that the multicast distribution tree can recover from failures and maintain efficient traffic forwarding. Avoiding periodic flooding is essential for maintaining network efficiency by preventing excessive unnecessary traffic, further illustrating that this protocol is designed to optimize multicast communication effectively.

The correct answer identifies that "All data packets are sent to multicast addresses" is not an assumption of Protocol Independent Multicast - Dense Mode (PIM-DM). In PIM-DM, multicast traffic is indeed primarily concerned with the efficient distribution of data using multicast addresses, but it does not necessarily assume that all data packets must be multicast.

In PIM-DM, the assumption is that there are interested receivers on the network that will join the multicast group, and therefore data is sent to multicast addresses dictated by those group memberships. However, there can be other forms of traffic that do not utilize multicast at all, particularly in scenarios where there are no interested receivers or where certain network policies dictate unicast transmission.

The other assumptions, such as each subnet having at least one interested receiver, packet forwarding being restored proactively, and the avoidance of periodic flooding, emphasize the operational characteristics of PIM-DM. Each subnet indeed must have at least one interested receiver for multicast traffic to be relevant. Proactive restoration of packet forwarding ensures that the multicast distribution tree can recover from failures and maintain efficient traffic forwarding. Avoiding periodic flooding is essential for maintaining network efficiency by preventing excessive unnecessary traffic, further illustrating that this protocol is designed to optimize multicast communication effectively.