Configuring IS-IS Local MT

With IS-IS local multicast topology (MT), multicast traffic can be transmitted over a traffic engineering (TE) tunnel, and the router through which the tunnel passes can generate multicast forwarding entries.

Usage Scenario

When multicast and a Multiprotocol Label Switching (MPLS) TE tunnel are configured on a network, the TE tunnel may send multicast packets which are transparent to the router through which the tunnel passes. As a result, the router cannot generate multicast forwarding entries. To resolve this problem, enable IS-IS local MT and Interior Gateway Protocol (IGP) Shortcut. If the outbound interface of a calculated route is an IGP Shortcut-enabled TE tunnel interface, the routing management (RM) module creates an independent Multicast IGP (MIGP) routing table. Multicast packets are then forwarded along the routes in the MIGP routing table.

IS-IS local MT takes effect only in public network IS-IS instances.

Pre-configuration Tasks

Before configuring IS-IS local MT, complete the following tasks:

Configure IP addresses for interfaces to ensure network connectivity between neighboring nodes.

Enabling Local MT: After local MT is enabled, routers through which a TE tunnel passes can generate multicast forwarding entries.

(Optional) Controlling the Size of the MIGP Routing Table: You can configure a filtering policy based on the multicast source address so that the router adds only the routes destined to the specified multicast source address to the independent Multicast IGP (MIGP) routing table, which controls the size of the MIGP routing table.

Verifying the Configuration of IS-IS Local MT: After configuring local MT, check the MIGP routing table, routing information, SPF tree, and IS-IS statistics.