Ip Multicast Tunnels - 3Com corebuilder 3500 Implementation Manual

IP Multicast Tunnels

Supporting Protocols in Your System
To communicate with other routers, your system supports the
Distance-Vector Multicast Routing Protocol (DVMRP) version 3.6. DVMRP
functions and configuration options are explained later in this chapter.
To communicate with group members on directly attached subnetworks,
your system supports the Internet Group Management Protocol (IGMP)
version 1 and version 2. IGMP functions are covered later in this chapter.
IP multicast routers are key connection points for delivering IP multicast
traffic between sources and multicast group members. In the event that
some routers in your network only transmit unicast packets, you can
configure a transitional technique called tunneling to extend the service
area. Tunnels provide a virtual point-to-point link between two multicast
routers, where the path between them includes one or more routers that
do not support multicast routing (unicast routers).
Figure 67 depicts a network configuration that requires an tunnel in order
for the PC to receive the IP multicast application. The multicast routers
support DVMRP, thus the tunnel is also configured with that protocol.
Figure 67 DVMRP Tunnel Example
IP multicast
router
Switch
IP multicast
application source
How a Network Supports IP Multicast
DVMRP tunnel
LAN
MAN
WAN
Unicast
Unicast
router
router
335
IP multicast
router
Switch
IP multicast
group member