Core issue
This issue occurs in lower versions of the Cisco Firewall Service Modules (FWSM).
Resolution
The FWSM 3.1.1 is the first version to support multicast traffic. The FWSM supports both stub multicast routing and Protocol Independent Multicast (PIM) routing. However, it is not advisible to configure both concurrently on a single FWSM.
The FWSM can also be configured as a member of a multicast group. When the FWSM is configured to join a multicast group, upstream routers maintain multicast routing table information for that group, and keep the paths active for that group.
For information on how to configure multicast traffic on the FWSM, refer to the Configuring Multicast Routing section of Configuring IP Routing and DHCP Services.
Note: When multicast routing is enabled, PIM and Internet Group Management Protocol (IGMP) are enabled on all interfaces by default. Also, multicast routing is not supported with multicontext in FWSM 2.3.
