Configuring multicast routing
The 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.
Static multicast
Static multicast allows you to configure static routes for multicast traffic between a source IP address and Engine interface pair, and a destination (multicast) IP address and 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 Engine maintains a list of multicast host group subscriptions and forwards traffic only to subscribed hosts. It periodically queries downstream networks for hosts requesting to join the multicast host group, and processes unsolicited IGMP join/leave requests from those networks. This approach saves bandwidth and provides faster service by sending multicast traffic only to currently subscribed hosts.
Note that IGMP-based multicast forwarding is supported only 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.