3com 5500-SI Manual De Usuario

This chapter includes information on the following:

■

■

■

■

■

■

The Switch 5500-EI supports all of the multicast protocols listed in this manual; 
however, the Switch 5500-SI only supports the IGMP Snooping protocol.

Many transmission methods can be used when the destination (including data, voice 
and video) is the secondary use of the network. If the multicast method is used you 
should establish an independent data transmission path for each user. The broadcast 
mode can be used if you intend to send the information to all users on the network. 
In either case, the end users will receive the information. For example, if the same 
information is required by 200 users on the network, the traditional solution is to 
send the information 200 times in unicast mode. In the broadcast mode, the data is 
broadcast over the entire network. However, both of the methods waste bandwidth 
resources. In addition, the broadcast mode cannot ensure information security.

IP multicast technology solves this problem. The multicast source sends the 
information only once. Multicast routing protocols establish tree-type routing for 
multicast packets. The information being sent will be replicated and distributed as far 
as possible (see Figure 78). Therefore, the information can be correctly sent, with high 
efficiency, to each user.