3Com MSR 50 Series Configuration Manual page 1090

1090 C 67: M
HAPTER ULTICAST
n
O
VERVIEW
Table 44 Class D IP address blocks and description
Address block
224.0.0.0 to
224.0.0.255
224.0.1.0 to
238.255.255.255
239.0.0.0 to
239.255.255.255
The membership of a group is dynamic. Hosts can join or leave multicast
■
groups at any time.
Glop" is a mechanism for assigning multicast addresses between different
■
autonomous systems (ASs). By filling an AS number into the middle two bytes
of 233.0.0.0, you get 255 multicast addresses for that AS.
Table 45 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 Distance vector multicast routing protocol (DVMRP) routers
224.0.0.5 Open shortest path first (OSPF) routers
224.0.0.6 OSPF designated routers/backup designated routers
224.0.0.7 Shared tree (ST) routers
224.0.0.8 ST hosts
224.0.0.9 Routing information protocol version 2 (RIPv2) routers
224.0.0.11 Mobile agents
224.0.0.12 Dynamic host configuration protocol (DHCP) server/relay agent
224.0.0.13 All protocol independent multicast (PIM) routers
224.0.0.14 Resource reservation protocol (RSVP) encapsulation
224.0.0.15 All core-based tree (CBT) routers
224.0.0.16 Designated subnetwork bandwidth management (SBM)
224.0.0.17 All SBMs
224.0.0.18 Virtual router redundancy protocol (VRRP)
IPv6 multicast addresses
As defined in RFC 4291, the format of an IPv6 multicast is as follows:
Description
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. Common
permanent group addresses are listed in
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.
Globally scoped group addresses. This block includes two types of
designated group addresses:
232.0.0.0/8: SSM group addresses, and
■
233.0.0.0/8: Glop group addresses; for details, see RFC 2770.
■
Administratively scoped multicast addresses for ASM/SFM. 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.
Table 45. A packet destined