H3C S9500 Series Operation Manual page 361

Operation Manual – Multicast Protocol
H3C S9500 Series Routing Switches
over the network if there is a large number of users in need of this information. As the
bandwidth would turn short, the unicast mode is incapable of massive transmission.
II. Data transmission in broadcast mode
In broadcast mode, every user on the network receives the information regardless of
their needs. See Figure 1-2 Data transmission in broadcast mode.
Broadcast
Server
Figure 1-2 Data transmission in broadcast mode
Suppose the Users B, D, and E need the information, the information source Server
broadcasts the information through the router; User A and User C can also receive the
information. In that case, information security and rewards to services are not
guaranteed. Moreover, bandwidth is terribly wasted when only a few part of users are in
need of the information.
In short, the unicast mode is useful in networks with scattered users, and the multicast
mode is suitable for networks with dense users. When the number of users is uncertain,
the adoption of unicast or multicast mode results in low efficiency.
1.1.2 Advantages of Multicast
I. Multicast
IP multicast technology solves those problems. When some users in the network need
specific information, it allows the multicast source to send the information only once.
With the tree route established by the multicast routing protocol, the information will not
be duplicated or distributed until it reaches the bifurcation point as far as possible. See
Figure 1-3 Data transmission in multicast mode.
User A
User B
User C
User D
User E
1-2
Chapter 1 IP Multicast Overview