Common Notations In Multicast - 3Com 4500 PWR 26-Port Configuration Manual

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 Laye
addition to providing multicast routing, a multicast router can also ma
mem bers.
F or a better understanding of the multicast concep
programs, a s shown in
Table 25-1 An analogy between TV transmission and multicast transmission
Step
A TV station transmits a TV program
1
through a television channel.
2 A user tunes the TV set to the channel.
The user starts to watch the TV program
3 transmitted by the TV station via the
channel.
4 The user turns off the TV set.
A multicast source does not necessarily belong to a multicast group. Namely, a multicast source is
not necessarily a multicast data
A multicast source can send
multicast sources can send data to the sam

Common Notations in Multicast

Two notations are commonly used in multicast:
(*, G): Indicates a
sends to multicast group G. Here "*" represent
specific multicast group.
(S, G): Indicates a sho
multicast group G. Here "S" represents a specific multicast source, while "G" represents a specific
multicast group.
Adva ntages and Applications of Multicast
Advantag es of multicast
Advantages of multicast in
Enhanced efficiency: Multicast decreases network traffic and reduces server load and CPU load.
Optimal performance: Multicast reduces redundant traffic.
Distributive application: Multicast makes multiple-p
Table 25-1.
TV transmission
receiver.
data to multiple multicast groups at the same time, and multiple
rendezvous point tree (RPT), or a multicast packet that any multicast source
rtest path tree (SPT), or a multicast packet that multicast source S sends to
clude:
25-4
t, yo u can use the analogy of a transmission of TV
Multicast transmission
A multicast source
multicast group.
A receiver joins the multicast group.
The receiver starts to receive the multicast
data that the source sends to the multicast
group.
The receiver leaves the multicast group.
e multicast group at the same time.
s any multicast source, while "G" represents a
oint application possible.
r 3 multicast device. In
nage multicast group
sends multicast data to a