User's Manual

001-2019-500 Rev 0

Paragon4 – UHF, 700 & 800MHz User Manual

6.8.5.1.2 Multicast

IP multicast addresses are in the range 224.0.0.0 to 239.255.255.255. These addresses are used to

represent logical groups of units that may or may not reside on the same networks.

Multicast is used when “one-to-many” communication is required. For instance, a radio station might of-

fer a music channel on the Internet in real time. To receive the music a receiver-host must know the mul-

ticast group (multicast address) used by the radio station sender-host and add itself as a member of this

group. In the IP realm, a host uses the IGMP protocol to do this. The routers inside the Internet are using

IGMP and other multicast routing protocols to build the proper path from the sender to the receivers (a

tree-like path is formed from the sender to the receivers).

Figure 44 - Registration to multicast group (First step)

Figure 45 - Reception of multicast packets (Second step)

Sender (owner of multicast group 226.1.2.3)

Receiver 1

(member of 226.1.2.3)

Receiver 2

(member of 226.1.2.3)

Receiver 3

(member of 226.1.2.3)

Internet

IP Router

Paths from Sender to Members

(Receivers 1, 2, and 3) flow in the

Internet from IP Router to IP Router

to reach

destinations 226.1.2.3.

Paths are not forwarded over inter-

faces that do not lead to a multicast

group member

Receiver

(not a member of 226.1.2.3)

Receiver

(not a member of 226.1.2.3)

Sender (owner of multicast group 226.1.2.3)

Receiver 1

(Add membership 226.1.2.3)

Receiver 2

(Add membership 226.1.2.3)

Receiver 3

(Add membership 226.1.2.3)

Internet