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A-2 APPENDIX A: IP MULTICAST ROUTING
Enabling and
Disabling DVMRP
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.
1 To enable or disable DVMRP, from the top level of the Administration
Console, enter:
ip multicast dvmrp
2 Enter the slot of the switching module for which you want to enable
DVMRP.
Select IP stack(s) by slot (2,3,7,9-12|all) [12]:
3 The interface prompts you to enable or disable DVMRP. The default is
disabled.
Slots 9-12 - Enter DVMRP mode (disabled, enabled) [disabled]:
enabled
Enabling and
Disabling IGMP
IGMP enables a router or switch to determine whether group members
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.
Top-Level Menu
system
ethernet
fddi
tokenring
bridge
➧ip
ipx
appletalk
snmp
analyzer
script
logout
interface
route
arp
➧multicast
udpHelper
routing
icmpRouterDiscovery
rip
ping
statistics
➧dvmrp
igmp
interfaces
tunnel
routeDisplay
cacheDisplay