Introduction:
Distance Vector Multicast Routing Protocol (DVMRP) was the first true multicast routing protocol.DVMRP is similar in many ways to Routing Information Protocol (RIP) with some minor variations added to support multicast.
Some key characteristics of DVMRP are
1) Distance vector based (similar to RIP)
2) Periodic route updates (every 60 seconds)
3) Infinity = 32 hops (versus 16 for RIP)
4) Poison Reverse has special meaning
5) Classless.
Description:
Frequently network administrators thinks that Cisco routers can be configured to run DVMRP instead of PIM. Although Cisco routers can't run DVMRP, they can be used as a PIM DVMRP gateways and interoperate with DVMRP routers.
As Cisco routers support DVMRP as a gateway to PIM. So the configuration is similar to the PIM configuration. The key difference is in the ip dvmrp unicast-routing command, which tells the router to use the DVMRP multicast routing table instead of the usual PIM choice of the unicast routing table
Router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#ip multicast-routing
Router(config)#interface FastEthernet0/0
Router(config-if)#ip pim sparse-dense-mode
Router(config-if)#ip dvmrp unicast-routing
Router(config-if)#ip dvmrp summary-address 10.1.0.0 255.255.0.0
To create a DVMRP tunnel from a Cisco router to a non Cisco DVMRP device by using the special DVMRP tunnel mode. This allows you to pass multicast traffic through a section of network that doesn't support multicast routing:
Router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#ip multicast-routing
Router(config)#interface Tunnel0
Router(config-if)#ip unnumbered FastEthernet0/0
Router(config-if)#ip pim sparse-dense-mode
Router(config-if)#ip dvmrp unicast-routing
Router(config-if)#tunnel source FastEthernet0/0
Router(config-if)#tunnel destination 10.1.1.10
Router(config-if)#tunnel mode dvmrp
Router(config-if)#exit
Router(config)#interface FastEthernet0/0
Router(config-if)#ip address 10.1.1.1 255.255.255.0
Router(config-if)#ip pim sparse-dense-mode
For more information on Cisco DVMRP Interoperability Configuration, refer to Configuring DVMRP Interoperability.Use Cisco Feature Navigator to find the latest information about platform support and Cisco IOS Software image support.
Also See
Distance Vector Multicast Routing Protocol
DVMRP RFC
