Accton Technology ES4626 - Manual (Page 612)

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16.1.2 Multicast Address
The destination address of Multicast message uses class D IP address with range
from 224.0.0.0 to 239.255.255.255. D class address can not appear in the source IP
address field of an IP message. In the process of Unicast data transmission, the
transmission path of a data packet is from source address routing to destination address,
and the transmission is performed with hop-by-hop principle. However, in IP Multicast
environment, the destination addresses is a group instead of a single one, they form a
group address. All message receivers will join in a group, and once they do, the data
flowing to the group address will be sent to the receivers immediately and all members in
the group will receive the data packets. The members in a Multicast group are dynamic,
the hosts can join and leave the Multicast group at any time.
Multicast group can be permanent or temporary. Some of the Multicast group
addresses are assigned officially; they are called Permanent Multicast Group. Permanent
Multicast Group keeps its IP address fixed but its member structure can vary within. The
member amount of Permanent Multicast Group can be arbitrary, even zero. The IP
Multicast addresses which are not kept for use by Permanent Multicast Group can be
utilized by temporary Multicast groups.
224.0.0. 0 ～ 224.0.0.255 are reserved Multicast addresses (Permanent Group
Address), address 224.0.0.0 is reserved but not assigned, and other addresses are used
by Routing Protocol; 224.0.1.0～238.255.255.255 are Multicast addresses available to
users（Temporary Group Address） and are valid in the entire domain of the network;
239.0.0.0～239.255.255.255 are local management Multicast addresses, which are valid
only in specific local domain. Frequently used reserved multicast address list is as
follows:
Benchmark address (reserved)
224.0.0.1 Address of all hosts
224.0.0.2 Address of all Multicast Routers
224.0.0.3 Unassigned
224.0.0.4 DVMRP Router
224.0.0.5 OSPF Router
224.0.0.6 OSPF DR
224.0.0.7 ST Router
224.0.0.8 ST host
224.0.0.9 RIP-2 Router
224.0.0.10 IGRP Router
224.0.0.11 Active Agent
224.0.0.12 DHCP Server/Relay Agent
224.0.0.13 All PIM Routers