Cisco Systems 3560 사용자 설명서

These are the SSM mapping configuration guidelines:

Before you configure SSM mapping, enable IP multicast routing, enable PIM sparse mode, and 
configure SSM. For information on enabling IP multicast routing and PIM sparse mode, see the 

Before you configure static SSM mapping, you must configure access control lists (ACLs) that 
define the group ranges to be mapped to source addresses. For information on configuring an ACL, 
see 

Before you can configure and use SSM mapping with DNS lookups, you must be able to add records 
to a running DNS server. If you do not already have a DNS server running, you need to install one.

You can use a product such as Cisco Network Registrar. Go to this URL for more information:

These are the SSM mapping restrictions:

The SSM mapping feature does not have all the benefits of full SSM. Because SSM mapping takes 
a group join from a host and identifies this group with an application associated with one or more 
sources, it can only support one such application per group. Full SSM applications can still share 
the same group as in SSM mapping.

Enable IGMPv3 with care on the last hop router when you rely solely on SSM mapping as a 
transition solution for full SSM. When you enable both SSM mapping and IGMPv3 and the hosts 
already support IGMPv3 (but not SSM), the hosts send IGMPv3 group reports. SSM mapping does 
not support these IGMPv3 group reports, and the router does not correctly associate sources with 
these reports.

In a typical STB deployment, each TV channel uses one separate IP multicast group and has one active 
server host sending the TV channel. A single server can send multiple TV channels, but each to a 
different group. In this network environment, if a router receives an IGMPv1 or IGMPv2 membership 
report for a particular group, the report addresses the well-known TV server for the TV channel 
associated with the multicast group.

When SSM mapping is configured, if a router receives an IGMPv1 or IGMPv2 membership report for a 
particular group, the router translates this report into one or more channel memberships for the 
well-known sources associated with this group.

When the router receives an IGMPv1 or IGMPv2 membership report for a group, the router uses SSM 
mapping to determine one or more source IP addresses for the group. SSM mapping then translates the 
membership report as an IGMPv3 report and continues as if it had received an IGMPv3 report. The 
router then sends PIM joins and continues to be joined to these groups as long as it continues to receive 
the IGMPv1 or IGMPv2 membership reports, and the SSM mapping for the group remains the same.