Roles In Multicast - H3C S5500-EI Series Operation Manual

Operation Manual – Multicast
H3C S5500-EI Series Ethernet Switches
Figure 1-3 Multicast transmission
Assume that Hosts B, D and E need the information. To receive the information
correctly, these hosts need to join a receiver set, which is known as a multicast group.
The routers on the network duplicate and forward the information based on the
distribution of the receivers in this set. Finally, the information is correctly delivered to
Hosts B, D, and E.
To sum up, multicast has the following advantages:
Over unicast: As multicast traffic flows to the node the farthest possible from the
source before it is replicated and distributed, an increase of the number of hosts
will not remarkably add to the network load.
Over broadcast: As multicast data is sent only to the receivers that need it,
multicast uses the network bandwidth reasonably and brings no waste of network
resources, and enhances network security.

1.1.2 Roles in Multicast

The following roles are involved in multicast transmission:
An information sender is referred to as a Multicast Source ("Source" in
Each receiver is a Multicast Group Member ("Receiver" in
All receivers interested in the same information form a Multicast Group. Multicast
groups are not subject to geographic restrictions.
A router that supports Layer 3 multicast is called multicast router or Layer 3
multicast device. In addition to providing the multicast routing function, a multicast
router can also manage multicast group members.
1-4
Chapter 1 Multicast Overview
Figure
Figure 1-3).
1-3).