Cisco IOS Cookbook, 2nd Edition

Routing Multicast Traffic with MOSPF

Problem

You want to distribute your multicast routing tables with MOSPF.

Solution

Unfortunately, Cisco does not support MOSPF. As mentioned in the Introduction to this chapter, MOSPF is a set of multicast extensions to OSPF that uses LSA Type 6. By default, when a Cisco router receives a Type 6 LSA packet it will generate a %OSPF- 4-BADLSATYPE error message. To avoid this error message, you can configure your routers to ignore Type 6 LSA packets:

Router#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#router ospf 65530
Router(config-router)#ospf ignore lsa mospf
Router(config-router)#end
Router#

Discussion

MOSPF has not enjoyed a particularly wide acceptance for several reasons, mostly related to the fact that it uses a dense-mode multicast-forwarding scheme, and because it is protocol dependant. It turns out to be most useful in networks that meet several key requirements:

• They should use a relatively small number of multicast applications.

• These applications should have few servers and many group members, with the group members scattered throughout the network.

• The network must use OSPF as its unicast protocol.

• The applications should deliver a flow of multicast traffic that is neither heavy enough to cause congestion problems on the slowest links in the network, nor so light that relationships time out in the routers.

Few router vendors have implemented MOSPF. Increasingly, the multicast routing protocol ...