4000 Router Series IP Multicast Configuration Guide

After receiving a report message, the DR first checks whether the group address in this message is in the

SSM group range and does the following:

• If the group address is in the SSM group range, the DR sends a subscribe message hop by hop

toward the multicast source S. All routers along the path from the DR to the source create an (S, G)

entry so as to build an SPT, which is rooted at the multicast source S and has the receivers as its

leaves. This SPT is the transmission channel in PIM-SSM.

• If the group address is not in the SSM group range, the receiver-side DR sends a (*, G) join message

to the RP, and the multicast source registers with the source-side DR.

In PIM-SSM, the term "channel" refers to a multicast group, and the term "subscribe message" refers to

a join message.

PIM support for VPNs

To support PIM for VPNs, a multicast router that runs PIM maintains an independent set of PIM neighbor

table, multicast routing table, BSR information, and RP-set information for each VPN.

After receiving a multicast data packet, the multicast router checks which VPN the data packet belongs

to, and then forwards the packet according to the multicast routing table for that VPN or creates a

multicast routing entry for that VPN.

Protocols and standards

• RFC 3973, Protocol Independent Multicast-Dense Mode (PIM-DM): Protocol Specification(Revised)

• RFC 4601, Protocol Independent Multicast-Sparse Mode (PIM-SM): Protocol Specification (Revised)

• RFC 5059, Bootstrap Router (BSR) Mechanism for Protocol Independent Multicast (PIM)

• RFC 4607, Source-Specific Multicast for IP

• Draft-ietf-ssm-overview-05, An Overview of Source-Specific Multicast (SSM)

Configuring PIM-DM

PIM-DM configuration task list

Task at a

lance

(Required.) Enabling PIM-DM

(Optional.) Enabling the state refresh feature

(Optional.) Configuring state refresh parameters

(Optional.) Configuring PIM-DM graft retry timer

(Optional.) Configuring common PIM features

Configuration prerequisites

Before you configure PIM-DM, configure a unicast routing protocol so that all devices in the domain are

interoperable at the network layer