# Configuring multicast routing

The Security Engine supports static multicast, IGMP-based multicast forwarding (IGMP proxying), and multicast routing using protocol-independent multicast (PIM). You can also configure dynamic multicast routing using the Free Range Routing (FRR) Suite on the command line.

IP multicasting is the transmission of an IP datagram to all hosts in a multicast host group, which is identified by a single destination IP address.

Static multicast is suitable for enduring configurations, while IGMP-based forwarding and PIM can save bandwidth and provide faster service.

Note: In addition to configuring the engine, routers and other network devices must be configured to allow IP multicasting along the path to the client machines.

## Static multicast

Static multicast allows you to configure static routes for multicast traffic between a source IP address and Security Engine interface pair, and a destination (multicast) IP address and Security Engine interface pair. Static multicast is often used for enduring configurations, such as mutually agreed multicast traffic between organizations (for example, multicast news feeds and video conferences).

## IGMP-based multicast forwarding

In IGMP-based multicast forwarding, the Security Engine maintains a list of subscriptions to the multicast host group and forwards multicast traffic to the subscribed hosts. The Security Engine periodically queries the downstream networks for hosts that want to join the multicast host group. The Security Engine also processes unsolicited IGMP join/leave requests received from downstream networks. As multicast traffic is only sent to the currently subscribed hosts, IGMP-based multicast forwarding can save bandwidth and provide faster service. IGMP-based multicast forwarding is only supported in tree topology networks. See RFC 4605 for more information.

## Protocol-independent multicast (PIM)

Three variants of PIM are supported: PIM sparse mode (PIM-SM), PIM dense mode (PIM-DM), and PIM source-specific multicast (PIM-SSM), and the mode can be set separately for different multicast groups.

## Limitations

- Only IPv4 addresses are supported in multicast routing.
- Multicast routing is not supported on Wireless Interfaces.
- IGMP Proxy mode for multicast routing is not supported on Tunnel Interfaces.