3com 8807 User Guide
37
IP M
ULTICAST
O
VERVIEW
n
An Ethernet switch functions as a router when it runs IP multicast protocol. A
router that is referred to in the following represents a generalized router or a layer
3 Ethernet switch running IP multicast protocol.
router that is referred to in the following represents a generalized router or a layer
3 Ethernet switch running IP multicast protocol.
IP Multicast Overview
Problems with
Unicast/Broadcast
The constant development of the Internet and increasing interaction of versatile
data, voice and video information over the network, has promoted the emergence
of new services like e-commerce, network conference, online auction, video on
demand (VoD), and tele-education. These services require higher information
security and greater rewards.
data, voice and video information over the network, has promoted the emergence
of new services like e-commerce, network conference, online auction, video on
demand (VoD), and tele-education. These services require higher information
security and greater rewards.
Data transmission in unicast mode
In unicast mode, every user that needs the information receives a copy through
the channels the system separately establishes for them. See Figure 96.
the channels the system separately establishes for them. See Figure 96.
Figure 96 Data transmission in unicast mode
Suppose that Users B, D, and E need the information, the information source
Server establishes transmission channels with every of them. Since the traffic in
transmission increases with the number of users, excessive copies of the
information would spread 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.
Server establishes transmission channels with every of them. Since the traffic in
transmission increases with the number of users, excessive copies of the
information would spread 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.
Data transmission in broadcast mode
In broadcast mode, every user on the network receives the information regardless
of their needs. See Figure 97 “Data transmission in broadcast mode”.
of their needs. See Figure 97 “Data transmission in broadcast mode”.
Server
Unicast
User A
User B
User C
User D
User E