3Com 6000 manual Enabling and Disabling DVMRP, Disabling IGMP

A-2 APPENDIX A: IP MULTICAST ROUTING

Enabling and Disabling DVMRP

Top-Level Menu
system
ethernet	interface
fddi	route	➧dvmrp
atm	arp	igmp
bridge
	atmArpServer	interfaces
➧ip
	➧multicast	tunnel
ipx
	udpHelper	routeDisplay
appletalk	routing	cacheDisplay
snmp	icmpRouterDiscovery
analyzer
	rip
script
	ping
logout
	statistics

DVMRP is the simple Distance Vector Multicast Routing Protocol, similar to the IP Routing Information Protocol. Multicast routers exchange distance vector updates that contain lists of destinations and the distance in hops to each destination. The routers maintain this information in a routing table.

To run multicast routing, you must enable DVMRP, which enables it on all IP interfaces that have not been disabled.

To enable or disable DVMRP, from the top level of the Administration Console, enter:

ip multicast dvmrp

The interface prompts you to enable or disable DVMRP. The default is disabled.

Example:

dvmrp mode (enabled/disabled)[disabled]: enabled

Enabling and	IGMP enables a router or switch to determine whether group members
Disabling IGMP	exist in a subnetwork, or “leaf,” of the Spanning Tree. It uses two search
	methods to make this determination:

■Query mode — The router or switch with the lowest IP address in the LAN broadcasts a query to all other members of the subnetwork to determine whether they are also in the group. End-stations respond to the query with IGMP packets, which report the multicast group to which they belong.

■Snooping mode — A router or switch performs dynamic multicast filtering based on IGMP snooping. This procedure ensures that multicast packets are flooded only to the appropriate ports within a routing interface.