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Catalyst 3560 Switch Software Configuration Guide
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Chapter 44 Configuring IP Multicast Routing
Configuring IP Multicast Routing
To disable multicasting, use the no ip multicast-routing distributed global configuration command.
To return to the default PIM version, use the no ip pim version interface configuration command. To
disable PIM on an interface, use the no ip pim interface configuration command.
Configuring Source-Specific Multicast
This section describes how to configure source-specific multicast (SSM). For a complete description of
the SSM commands in this section, refer to the “IP Multicast Routing Commands” chapter of the Cisco
IOS IP Command Reference, Volume 3 of 3: Multicast. To locate documentation for other commands that
appear in this chapter, use the command reference master index, or search online.
The SSM feature is an extension of IP multicast in which datagram traffic is forwarded to receivers from
only those multicast sources that the receivers have explicitly joined. For multicast groups configured
for SSM, only SSM distribution trees (no shared trees) are created.

SSM Components Overview

SSM is a datagram delivery model that best supports one-to-many applications, also known as broadcast
applications. SSM is a core networking technology for the Cisco implementation of IP multicast
solutions targeted for audio and video broadcast application environments. The switch supports these
components that support the implementation of SSM:
• Protocol independent multicast source-specific mode (PIM-SSM)
PIM-SSM is the routing protocol that supports the implementation of SSM and is derived from PIM
sparse mode (PIM-SM).
• Internet Group Management Protocol version 3 (IGMPv3)
To run SSM with IGMPv3, SSM must be supported in the Cisco IOS router, the host where the
application is running, and the application itself.
Step 5 ip pim {dense-mode | sparse-mode |
sparse-dense-mode}
Enable a PIM mode on the interface.
By default, no mode is configured.
The keywords have these meanings:
• dense-mode—Enables dense mode of operation.
• sparse-mode—Enables sparse mode of operation. If you configure
sparse mode, you must also configure an RP. For more information,
see the “Configuring a Rendezvous Point” section on page 44-23.
• sparse-dense-mode—Causes the interface to be treated in the mode
in which the group belongs. Sparse-dense mode is the recommended
setting.
Step 6 end Return to privileged EXEC mode.
Step 7 show running-config Verify your entries.
Step 8 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose