
Operation Manual – Multicast
H3C S5500-EI Series Ethernet Switches
Chapter 1 Multicast Overview
1-7
hosts, and the TCP/IP stack must support reception and transmission of multicast
data.
1.3.1 Multicast Addresses
To allow communication between multicast sources and multicast group members,
network-layer multicast addresses, namely, multicast IP addresses must be provided.
In addition, a technique must be available to map multicast IP addresses to link-layer
multicast MAC addresses.
I. IPv4 multicast addresses
Internet Assigned Numbers Authority (IANA) assigned the Class D address space
(224.0.0.0 to 239.255.255.255) for IPv4 multicast. The specific address blocks and
usages are shown in
Table 1-2
.
Table 1-2
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, and other IP
addresses can be used by routing protocols and for
topology searching, protocol maintenance, and so
on. Commonly used permanent group addresses
are listed in
Table 1-3
. A packet destined for an
address in this block will not be forwarded beyond
the local subnet regardless of the Time to Live
(TTL) value in the IP header.
224.0.1.0 to 238.255.255.255
Globally scoped group addresses. This block
includes two types of designated group addresses:
z
232.0.0.0/8: SSM group addresses, and
z
233.0.0.0/8: Glop group addresses; for details,
see RFC 2770.
239.0.0.0 to 239.255.255.255
Administratively scoped multicast addresses.
These addresses are considered to be locally
rather than globally unique, and can be reused in
domains administered by different organizations
without causing conflicts. For details, refer to RFC
2365.