Cisco Systems 3560 Manual Do Utilizador

In PIM-SSM, the last hop router continues to periodically send (S, G) join messages if appropriate (S, 
G) subscriptions are on the interfaces. Therefore, as long as receivers send (S, G) subscriptions, the 
shortest path tree (SPT) state from the receivers to the source is maintained, even if the source does not 
send traffic for longer periods of time (or even never).

This case is opposite to PIM-SM, where (S, G) state is maintained only if the source is sending traffic 
and receivers are joining the group. If a source stops sending traffic for more than 3 minutes in PIM-SM, 
the (S, G) state is deleted and only re-established after packets from the source arrive again through the 
RPT. Because no mechanism in PIM-SSM notifies a receiver that a source is active, the network must 
maintain the (S, G) state in PIM-SSM as long as receivers are requesting receipt of that channel.

Beginning in privileged EXEC mode, follow these steps to configure SSM:

Beginning in privileged EXEC mode, follow these steps to monitor SSM.

The Source Specific Multicast (SSM) mapping feature supports SSM transition when supporting SSM 
on the end system is impossible or unwanted due to administrative or technical reasons. You can use 
SSM mapping to leverage SSM for video delivery to legacy STBs that do not support IGMPv3 or for 
applications that do not use the IGMPv3 host stack.

This section covers these topics:

ip pim ssm [default | range access-list]

Define the SSM range of IP multicast addresses.

interface type number

Select an interface that is connected to hosts on which 
IGMPv3 can be enabled, and enter the interface configuration 
mode.

ip pim {sparse-mode | sparse-dense-mode}

Enable PIM on an interface. You must use either sparse mode 
or sparse-dense mode.

ip igmp version 3

Enable IGMPv3 on this interface. The default version of 
IGMP is set to Version 2.

end

Return to privileged EXEC mode.

Verify your entries.

(Optional) Save your entries in the configuration file.

Router# show ip igmp groups detail

Display the (S, G) channel subscription through IGMPv3.

Router# show ip mroute

Display whether a multicast group supports SSM service or 
whether a source-specific host report was received.