R21xx-HP FlexFabric 11900 IP Multicast Configuration Guide

Table Of Contents

• Where is the multicast source that will provide data to the receivers? (Multicast source discovery.)

• How should information be transmitted to the receivers? (Multicast routing.)

IP multicast is an end-to-end service. The multicast architecture involves the following parts:

• Addressing mechanism—A multicast source sends information to a group of receivers through a

multicast address.

• Host registration—Receiver hosts can join and leave multicast groups dynamically. This mechanism

is the basis for management of group memberships.

• Multicast routing—A multicast distribution tree (a forwarding path tree for multicast data on the

network) is constructed for delivering multicast data from a multicast source to receivers.

• 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:

IANA assigned the Class D address block (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. You can

reuse them in domains administered by different organizations

without causing conflicts. For more information, see RFC 2365.

NOTE:

"Glop" is a mechanism for assi

nin

multicast addresses between different ASs. By fillin

an AS numbe

into the middle two bytes of 233.0.0.0, you get 255 multicast addresses for that AS. For more

information, see RFC 2770.