H3C Technologies H3C S12500 Series Switches - Manual (Page 22)

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• Multicast applications—A software system that supports multicast applications, such as video
conferencing, must be installed on multicast sources and receiver hosts. The TCP/IP stack must
support reception and transmission of multicast data.
Multicast addresses
IP multicast addresses
• IPv4 multicast addresses:
Internet Assigned Numbers Authority (IANA) assigned the Class D address space (224.0.0.0 to
239.255.255.255) to IPv4 multicast.
Table 2 Class D IP address blocks and description
Address block Description
224.0.0.0 to 224.0.0.255
Reserved permanent group addresses. The IP address
224.0.0.0 is reserved. Other IP addresses can be used by
routing protocols and for topology searching, protocol
maintenance, and so on. Table 3 lists common permanent
group addresses. A packet destined for an address in this block
will not be forwarded beyond the local subnet regardless of the
TTL value in the IP header.
224.0.1.0 to 238.255.255.255
Globally scoped group addresses. This block includes the
following types of designated group addresses:
• 232.0.0.0/8—SSM group addresses.
• 233.0.0.0/8—Glop group addresses.
239.0.0.0 to 239.255.255.255
Administratively scoped multicast addresses. These addresses
are considered locally unique rather than globally unique, and
can be reused in domains administered by different
organizations without causing conflicts. For more information,
see RFC 2365.
NOTE:
"Glop" is a mechanism for assigning multicast addresses between different ASs. By filling an AS
number into the middle two bytes of 233.0.0.0, you get 255 multicast addresses for that AS. For more
information, see RFC 2770.
Table 3 Some reserved multicast addresses
Address Description
224.0.0.1 All systems on this subnet, including hosts and routers.
224.0.0.2 All multicast routers on this subnet.
224.0.0.3 Unassigned.
224.0.0.4 DVMR routers.
224.0.0.5 OSPF routers.
224.0.0.6 OSPF designated routers/backup designated routers.
224.0.0.7 ST routers.