Multicast demands

A multicast demand is a network traffic requirement that

• specifies how multicast flows are to be handled within a network simulation

• can be inserted manually for discovered multicast flows, and

• must be created manually for simulated multicast flows.

For manually inserted demands, all SSM demand traffic for the (S,G) pair (multicast flow) goes through any interface that is traversed by that demand. SSM demands are routed to take the shortest path from the destination to the source, rather than from the source to the destination, as unicast demands do. By default, multicast multipath is disabled. If two paths of equal cost exit from a node on the route back to the source, the path is chosen based on:

• The remote interface with the highest IP address is used.

• If IP addresses are not available, the router name with the lowest lexicographical name is used.

However, you can set Cisco Crosswork Planning to use the Cisco next-hop multicast, multipath selection method. For more information, refer to Configure Cisco next hop for multicast flows.

The sources of these multicast demands can be nodes, interfaces, external ASes, or external endpoints. Using interfaces lets you specify the exact interface on which demand traffic is entering. Using external endpoints lets you model situations where the multicast source is outside of the nodes in the plan, and there is more than one possible entry point of the traffic flow into and through the interfaces in the plan.