H3c-technologies H3C S3100V2 Series Switches Manual de usuario descargar pdf (Pagina 14)

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

Network-layer multicast addresses—namely, multicast IP addresses—enable communication between

multicast sources and multicast group members. In addition, a technique must be available to map

multicast IP addresses to link-layer multicast MAC addresses.

IP multicast addresses

1. 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.

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 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 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:

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

• “Glop” is a mechanism for assi

nin

multicast addresses between different autonomous systems (ASs).

By fillin

an AS number into the middle two bytes of 233.0.0.0, you

et 255 multicast addresses for tha

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 Distance Vector Multicast Routing Protocol (DVMRP) routers

224.0.0.5 Open Shortest Path First (OSPF) routers

1 2 ... 9 10 11 12 13 14 15 16 17 18 19 ... 110 111

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