3Com 5500-SI Configuration Manual page 311

Ranges and meanings of Class D addresses are shown in Table 306
Table 306 Ranges and meaning of Class D addresses
Class D address range
224.0.0.0~224.0.0.255
224.0.1.0~238.255.255.255
239.0.0.0~239.255.255.255
Reserved multicast addresses that are commonly used are shown in Table 307.
Table 307 Reserved multicast address list
Class D address
224.0.0.0
224.0.0.1
224.0.0.2
224.0.0.3
224.0.0.4
224.0.0.5
224.0.0.6
224.0.0.7
224.0.0.8
224.0.0.9
224.0.0.10
224.0.0.11
224.0.0.12
224.0.0.13
224.0.0.14
224.0.0.15
224.0.0.16
224.0.0.17
224.0.0.18
....
Ethernet Multicast MAC Addresses
When unicast IP packets are transmitted in Ethernet, the destination MAC address is
the MAC address of the receiver. However, when multicast packets are transmitted,
the destination is no longer a specific receiver but a group with unspecific members.
Therefore, the multicast MAC address should be used. Multicast MAC addresses
correspond to multicast IP addresses. IANA (Internet Assigned Number Authority)
stipulates that the higher 24 bits of the multicast MAC address is 0x01005e and the
lower 23 bits of the MAC address is the lower 23 bits of the multicast IP address.
IP Multicast Overview 311
Meaning
Reserved multicast addresses (addresses of permanent
groups). Address 224.0.0.0 is reserved. The other
addresses can be used by routing protocols.
Multicast addresses available for users (addresses of
temporary groups). They are valid in the entire network.
Multicast addresses for local management. They are valid
only in the specified local range.
Meaning
Base Address (Reserved)
Addresses of all hosts
Addresses of all multicast routers
Unassigned
DVMRP routers
OSPF routers
OSPF DR (designated router)
ST routers
ST hosts
RIP-2 routers
IGRP routers
Mobile agents
DHCP server/Relay agent
All PIM routers
RSVP encapsulation
All CBT routers
Designated SBM
All SBMS
VRRP
....