Alcatel-Lucent 6850 Switch User Manual


 
Configuring DVMRP DVMRP Overview
OmniSwitch 6800/6850/9000 Advanced Routing Configuration Guide December 2007 page 6-9
DVMRP Tunnels
Because not all IP routers support native multicast routing, DVMRP includes direct support for tunneling
IP multicast packets through routers. Tunnel interfaces are used when routers incapable of supporting
multicast traffic exist between DVMRP neighbors. In tunnel interfaces, IP multicast packets are encapsu-
lated in unicast IP packets and addressed directly to the routers that do not support native multicast rout-
ing. DVMRP protocol messages (such as Route Reports, Probes for neighbor discovery, etc.) and
multicast traffic are sent between tunnel endpoints using unicast, rather than multicast, packets.
Multicast data is encapsulated using a standard IP-IP encapsulation method. The unicast IP addresses of
the tunnel endpoints are used as the source and destination IP addresses in the outer IP header. The inner
IP header remains unchanged from the original multicast packet.