Connecting IP Multicast Domains: PIM Dense Mode to PIM Sparse Mode

A.

When connecting an IP multicast domain that operates in PIM dense mode to a PIM sparse mode domain, it is essential to consider the compatibility between the two modes of operation. PIM (Protocol Independent Multicast) is a multicast routing protocol used to build multicast distribution trees in IP networks.

In PIM dense mode, multicast traffic is initially flooded to all links in a network, and then pruned back to the desired recipients. This method can result in high network traffic and is therefore inefficient for large networks.

On the other hand, PIM sparse mode uses a rendezvous point (RP) to efficiently manage multicast traffic by forwarding traffic only to those receivers who explicitly request it. This method reduces network traffic and is more efficient for large networks.

To connect an IP multicast domain that is operating in PIM dense mode to a PIM sparse mode domain, the connection can be made at any location in the network. However, PIM sparse mode and PIM dense mode are not interoperable, and IGMP (Internet Group Management Protocol) must be used to provide the interconnection.

IGMP is a protocol used by hosts to inform neighboring routers of their interest in receiving multicast traffic for a specific group. IGMP is used in conjunction with PIM to ensure that multicast traffic is properly forwarded to all interested hosts in a network.

Therefore, the correct answer is D. The connection can be made at any location in the network, but PIM sparse mode and PIM dense mode cannot inter-operate; IGMP must be used to provide the interconnection.