| 8.4 |  | Routing and Multicast Configuration |
| 8.4.5 |  | Forwarding multicasts from a transmission source |

| Multicast Forwarding to a downstream host When a multicast transmission source is on a protected or more secure interface of a PIX Security Appliance, the user must specifically configure the PIX Security Appliance to forward multicast transmissions from the source. Enable multicast forwarding on the PIX Security Appliance interfaces toward each network containing hosts that are registered to receive the multicast transmissions.

The PIX Security Appliance can be configured to forward multicast transmissions from an inside source by completing the following steps:

1. Use the multicast interface command to enable multicast forwarding on each PIX Security Appliance interface .
2. Use the mroute command to create a static route from the transmission source to the next-hop router interface. To clear static multicast routes, use the clear mroute command. The syntax for the mroute command is as follows :

   > mroute src smask in-if-name dst dmask out-if-name

In Figure , hosts on the inside and DMZ interface transmit multicasts to members of group 230.1.1.2. There are no internal receivers. Multicast traffic is enabled on the inside and outside interfaces. A static multicast route is configured to enable inside host 10.0.0.11 to transmit multicasts to members of group 230.1.1.2.

The IGMP version and timers can be specified with the igmp version, igmp query-interval, and igmp query-max-response-time commands as shown in Figure . See the Online Command Reference for further configuration details.