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H3C Technologies H3C WX6000 Series Access Controllers User Manual

Page 313

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28-7

Table 28-2

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 28-3

. 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.

z

The membership of a group is dynamic. Hosts can join or leave multicast groups at any time.

z

“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 28-3

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 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