
224.0.0.2
224.0.0.3
224.0.0.4
224.0.0.5
224.0.0.6
224.0.0.7
224.0.0.8
224.0.0.9
224.0.0.10
224.0.0.11
224.0.0.12
224.0.0.13
224.0.0.14
224.0.0.15
224.0.0.16
224.0.0.17
224.0.0.18
224.0.0.19 through 224.0.0.225 224.0.0.21
All Routers on this subnet Unassigned
DVMRP Routers
OSPF IGP Routers
OSPF IGP Designated Routers ST Routers
ST Hosts
All RIP2 Routers
All IGRP Routers
Mobile Agents
DHCP Servers and Relay Agents All PIM Routers
RSVP Encapsulation
All CBT Routers
Designated Sbm
All Sbms
VRRP
Unassigned
DVMRP on MOSPF
Table
Internet Group Management Protocol (IGMP)
End users that want to receive multicast packets must be able to inform nearby routers that they want to become a multicast group member of the group these packets are being sent to. The Internet Group Management Protocol (IGMP) is used by multicast routers to maintain multicast group membership. IGMP is also used to coordinate between multiple multicast routers that may be present on a network by electing one of the multicast routers as the ‘querier’. This router then keep track of the membership of multicast groups that have active members on the network. IGMP is used to determine whether the router should forward multicast packets it receives to the subnetworks it is attached to or not. A multicast router that has received a multicast packet will check to determine if there is at least one member of a multicast group that has requested to receive multicast packets from this source. If there is one member, the packet is forwarded. If there are no members, the packet is dropped.
58