Distance Vector Multicast Routing Protocol (DVMRP)

An earlier version of DVMRP was documented as RFC 1075 but it is not representative of the protocol in use today. The GATED version of DVMRP is compatible with the XEROX PARC releases 2.x and 3.x. It will perform pruning and grafting if the upstream neighbor supports it. It understands the capability flags introduced in XEROX PARC Release 3.5. It does not yet support the IP Multicast Traceroute or the DVMRP MIB. Stay tuned for these features.

This is a preliminary release of DVMRP. There is not currently a method to inject source networks into the DVMRP unicast routing protocol from other regions running different IP Multicast routing protocols such as PIM. This feature will be released as soon as a safe method for doing so has been tested.

The DVMRP Statement

dvmrp yes | no | on | off [ {
    interface interface_list
	[enable | disable]
	[metric metric]
	[threshold threshold]
	[ratelimit rate] ;
    tunnel host lcladdr local_address
	[enable | disable]
	[metric metric]
	[threshold threshold]
	[ratelimit rate] ;
    traceoptions trace_options ;
} ] ;

The dvmrp statement enables or disables the DVMRP protocol. If the dvmrp statement is not specified the default is dvmrp off; If enabled, DVMRP will default to enabling all interfaces that are multicast capable. These interfaces are identified by the IFF_MULTICAST interface flag.

Note: only one multicast routing protocol can be configured on a port at a time.

The options are as follows:

interface interface_list

Enables or disables DVMRP on this interface or list of interfaces.

Currently, the gated implementation of DVMRP cannot detect when there are multiple addresses configured on the same physical interface. It will send DVMRP messages to each logical network. This should be fixed in a future release.

The possible parameters are:

disable

Specifies that DVMRP packets received via the specified interface will be ignored. The default is to listen to DVMRP on all multicast capable interfaces.

enable

This is the default. This argument may be necessary when disable is used on a wildcard interface descriptor.

metric

This command provides a way to configure the metric on a physical port or tunnel. This metric will be added to all routes that are learned via this interface.

threshold

This command provides a way to configure the threshold on a physical port or tunnel. A packet will not be forwarded out this interface unless the TTL in the packet exceeds this threshold.

ratelimit

This command provides a way to limit the rate of multicast traffic on an interface. It is an option in the XEROX PARC IP Multicast kernel (Release 3.3 or greater).

tunnel host lcladdr local_address

The tunnel statement uses the same options as the interface statement.

traceoptions trace_options

Specifies the tracing options for DVMRP. (See Trace Statements and the DVMRP specific tracing options below.)

Tracing options

packets

All DVMRP packets.

probe

DVMRP Router Probe packets

report

DVMRP Route Report packets

mapper

DVMRP Neighbor and Neighbor 2 packets

prune

DVMRP Prune packets

graft

DVMRP Graft and Graft Ack packets

Sample DVMRP configurations