48-54
Catalyst 3750-X and 3560-X Switch Software Configuration Guide
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Chapter 48 Configuring IP Multicast Routing
Configuring Advanced DVMRP Interoperability Features
To prevent the default route advertisement, use the no ip dvmrp default-information interface
configuration command.

Responding to mrinfo Requests

The software answers mrinfo requests sent by mrouted systems and Cisco routers and multilayer
switches. The software returns information about neighbors through DVMRP tunnels and all the routed
interfaces. This information includes the metric (always set to 1), the configured TTL threshold, the
status of the interface, and various flags. You can also use the mrinfo privileged EXEC command to
query the router or switch itself, as in this example:
Switch# mrinfo
171.69.214.27 (mm1-7kd.cisco.com) [version cisco 11.1] [flags: PMS]:
171.69.214.27 -> 171.69.214.26 (mm1-r7kb.cisco.com) [1/0/pim/querier]
171.69.214.27 -> 171.69.214.25 (mm1-45a.cisco.com) [1/0/pim/querier]
171.69.214.33 -> 171.69.214.34 (mm1-45c.cisco.com) [1/0/pim]
171.69.214.137 -> 0.0.0.0 [1/0/pim/querier/down/leaf]
171.69.214.203 -> 0.0.0.0 [1/0/pim/querier/down/leaf]
171.69.214.18 -> 171.69.214.20 (mm1-45e.cisco.com) [1/0/pim]
171.69.214.18 -> 171.69.214.19 (mm1-45c.cisco.com) [1/0/pim]
171.69.214.18 -> 171.69.214.17 (mm1-45a.cisco.com) [1/0/pim]
Configuring Advanced DVMRP Interoperability Features
Cisco routers and multilayer switches run PIM to forward multicast packets to receivers and receive
multicast packets from senders. It is also possible to propagate DVMRP routes into and through a PIM
cloud. PIM uses this information; however, Cisco routers and multilayer switches do not implement
DVMRP to forward multicast packets.
These sections contain this configuration information:
• Enabling DVMRP Unicast Routing, page 48-54 (optional)
• Rejecting a DVMRP Nonpruning Neighbor, page 48-55 (optional)
• Controlling Route Exchanges, page 48-58 (optional)
For information on basic DVMRP features, see the “Configuring Basic DVMRP Interoperability
Features” section on page 48-49.

Enabling DVMRP Unicast Routing

Because multicast routing and unicast routing require separate topologies, PIM must follow the
multicast topology to build loopless distribution trees. Using DVMRP unicast routing, Cisco routers,
multilayer switches, and mrouted-based machines exchange DVMRP unicast routes, to which PIM can
then reverse-path forward.
Step 4 end Return to privileged EXEC mode.
Step 5 show running-config Verify your entries.
Step 6 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose