Cisco Systems 78-11741-02 manual Advertising Network 0.0.0.0 to Dvmrp Neighbors, IPC-540

Configuring DVMRP Interoperability

Advanced DVMRP Interoperability Configuration Task List

See the “DVMRP Tunnel Example” section later in this chapter for an example of how to configure a DVMRP tunnel.

Advertising Network 0.0.0.0 to DVMRP Neighbors

The mrouted protocol is a public domain implementation of DVMRP. If your router is a neighbor to an mrouted Version 3.6 device, you can configure the Cisco IOS software to advertise network 0.0.0.0 to the DVMRP neighbor. Do not advertise the DVMRP default into the MBONE. You must specify whether only route 0.0.0.0 is advertised or if other routes can also be specified.

To advertise network 0.0.0.0 to DVMRP neighbors on an interface, use the following command in interface configuration mode:

Command	Purpose
Router(config-if)#ip dvmrp default-information	Advertises network 0.0.0.0 to DVMRP neighbors.
{originate only}

Advanced DVMRP Interoperability Configuration Task List

Cisco routers run PIM and know enough about DVMRP to successfully 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 do not implement DVMRP to forward multicast packets.

The basic DVMRP interoperability features are described in the section “Basic DVMRP Interoperability Configuration Task List” earlier in this chapter. To configure more advanced DVMRP interoperability features on a Cisco router, perform the optional tasks described in the following sections:

•Enabling DVMRP Unicast Routing (Optional)

•Limiting the Number of DVMRP Routes Advertised (Optional)

•Changing the DVMRP Route Threshold (Optional)

•Configuring a DVMRP Summary Address (Optional)

•Disabling DVMRP Automatic summarization (Optional)

•Adding a Metric Offset to the DVMRP Route (Optional)

•Rejecting a DVMRP Nonpruning Neighbor (Optional)

•Configuring a Delay Between DVRMP Reports (Optional)

Enabling DVMRP Unicast Routing

Because policy for multicast routing and unicast routing requires separate topologies, PIM must follow the multicast topology to build loopless distribution trees. Using DVMRP unicast routing, Cisco routers and mrouted machines exchange DVMRP unicast routes, to which PIM can then reverse path forward.

Cisco routers do not perform DVMRP multicast routing among each other, but they can exchange DVMRP routes. The DVMRP routes provide a multicast topology that may differ from the unicast topology. These routes allow PIM to run over the multicast topology, thereby allowing PIM sparse mode over the MBONE topology.

Cisco IOS IP Configuration Guide

IPC-540