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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter46 Configuring IP Multicast Routing
Configuring Advanced DVMRP Interoperability Features
Beginning in privileged EXEC mode, follow these steps to advertise network 0.0.0.0 to DVMRP
neighbors on an interface. This procedure is optional.
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.
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface interface-id Specify the interface that is connected to the DVMRP router, and enter
interface configuration mode.
Step3 ip dvmrp default-information
{originate | only}
Advertise network 0.0.0.0 to DVMRP neighbors.
Use this command only when the switch is a neighbor of mrouted
Version 3.6 machines.
The keywords have these meanings:
•originate—Specifies that other routes more specific than0.0.0.0 can
also be advertised.
•only—Specifies that no DVMRP routes other than 0.0.0.0 are
advertised.
Step4 end Return to privileged EXEC mode.
Step5 show running-config Verify your entries.
Step6 copy running-config startup-config (Optional) Save your entries in the configuration file.