46-20
Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter46 Configuring IP Multicast Routing
Configuring IP Multicast Routing
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
See your DNS server documentation for more information about configuring DNS resource records. For
information on SSM mapping:
http://www.cisco.com/en/US/docs/ios/12_3t/12_3t2/feature/guide/gtssmma.html
Configuring SSM Mapping
Configuring Static SSM Mapping, page46-20 (required)
Configuring DNS-Based SSM Mapping, page46-21 (required)
Configuring Static Traffic Forwarding with SSM Mapping, page46-22 (optional)

Configuring Static SSM Mapping

Beginning in privileged EXEC mode, follow these steps to configure static SSM mapping:
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 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.
Step3 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.
Step4 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.
Step5 Repeat Step 4 to configure additional
static SSM mappings, if required.
Step6 end Return to privileged EXEC mode.
Step7 show running-config Verify your entries.
Step8 copy running-config startup-config (Optional) Save your entries in the configuration file.