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Catalyst 3560 Switch Software Configuration Guide
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Chapter 44 Configuring IP Multicast Routing
Configuring IP Multicast Routing
switchover mechanism. One video source is active, and the other backup video source is passive. The
passive source waits until an active source failure is detected before sending the video traffic for the TV
channel. Thus, the server-side switchover mechanism ensures that only one of the servers is actively
sending video traffic for the TV channel.
To look up one or more source addresses for a group that includes G1, G2, G3, and G4, you must
configure these DNS records on the DNS server:
G4.G3.G2.G1 [multicast-domain] [timeout]IN A source-address-1
IN A source-address-2
IN A source-address-n
Refer to your DNS server documentation for more information about configuring DNS resource records,
and go to this URL for additional information on SSM mapping:
http://www.cisco.com/en/US/products/sw/iosswrel/ps5207/products_feature_guide09186a00801a6d6f.
html
Configuring SSM Mapping
This section covers these topics:
• Configuring Static SSM Mapping, page 44-19 (required)
• Configuring DNS-Based SSM Mapping, page 44-20 (required)
• Configuring Static Traffic Forwarding with SSM Mapping, page 44-20 (optional)

Configuring Static SSM Mapping

Beginning in privileged EXEC mode, follow these steps to configure static SSM mapping:
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 ip igmp ssm-map enable Enable SSM mapping for groups in the configured SSM range.
Note By default, this command enables DNS-based SSM mapping.
Step 3 no ip igmp ssm-map query dns (Optional) Disable DNS-based SSM mapping.
Note Disable DNS-based SSM mapping if you only want to rely on
static SSM mapping. By default, the ip igmp ssm-map global
configuration command enables DNS-based SSM mapping.
Step 4 ip igmp ssm-map static access-list
source-address
Configure static SSM mapping.
The ACL supplied for access-list defines the groups to be mapped to the
source IP address entered for the source-address.
Note You can configure additional static SSM mappings. If additional
SSM mappings are configured and the router receives an
IGMPv1 or IGMPv2 membership report for a group in the SSM
range, the switch determines the source addresses associated
with the group by using each configured ip igmp ssm-map
static command. The switch associates up to 20 sources per
group.
Step 5 Repeat Step 4 to configure additional
static SSM mappings, if required.
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