Multicast Features - HP A6600 Configuration Manual

Figure 3 Multicast transmission
The multicast source sends only one copy of the information to a multicast group. In
and E, which are receivers of the information, must join the multicast group. The routers on the network
duplicate and forward the information based on the distribution of the group members. Finally, the
information is correctly delivered to Hosts B, D, and E.
The advantages of multicast over unicast and broadcast include:
• unicast—Because multicast traffic flows to the farthest-possible node from the source before it is
replicated and distributed, an increase in the number of hosts does not increase the load of the
source and does not significatly add to the usage of network resources.
broadcast—Because multicast data is sent only to the receivers that need it, multicast uses network
•
bandwidth reasonably and enhances network security. In addition, data broadcast is confined to
the same subnet, while multicast is not.

Multicast features

Multicast features include:
A multicast group is a multicast receiver set identified by an IP multicast address. Hosts join a
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multicast group to become members of the multicast group, before they can receive the multicast
data addressed to that multicast group. Typically, a multicast source does not need to join a
multicast group.
An information sender is called a "multicast source." A multicast source can send data to multiple
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multicast groups at the same time, and multiple multicast sources can send data to the same multicast
group at the same time.
• All hosts that have joined a multicast group become members of the multicast group. The group
memberships are dynamic. Hosts can join or leave multicast groups at any time. Multicast groups
are not subject to geographic restrictions.
Routers or Layer 3 switches that support Layer 3 multicast are called "multicast routers" or "Layer 3
•
multicast devices." In addition to providing the multicast routing function, a multicast router can
manage multicast group memberships on stub subnets with attached group members. A multicast
router itself can be a multicast group member.
3
Figure 3, Hosts B, D,