Configuring a Multicast Loopback Interface

Context

VPN multicast packets are encapsulated into public network multicast data packets using Generic Routing Encapsulation (GRE) before they can be transmitted on a public network. The switch encapsulates VPN packets into public network packets only after a multicast loopback interface is configured. When VPN multicast packets reach a PE, these packets are directed to member interfaces of the multicast loopback interface for encapsulation.

Perform the following steps on a PE.

Procedure

Run system-view
The system view is displayed.
(Optional) Run set multicast tunnel enhanced
An Eth-Trunk that works as a multicast VPN loopback interface can have member interfaces from different cards.

By default, the member interfaces of an Eth-Trunk that works as a multicast VPN loopback interface must be located on the same card.
Run interface eth-trunk trunk-id
The Eth-Trunk interface view is displayed.
Run service type multicast-tunnel
The Eth-Trunk interface is configured as a multicast loopback interface.
- On the PE, only one Eth-Trunk interface can function as the multicast loopback interface. All VPN multicast packets are encapsulated into public network multicast data packets on this interface.
- An Eth-Trunk interface cannot function as the multicast loopback interface if it has member interfaces or other services configured.
- Before disabling an Eth-Trunk interface from working as the multicast loopback interface, delete all member interfaces from the Eth-Trunk interface.
- If an Eth-Trunk interface has multiple member interfaces, it is recommended that you run the unknown-unicast load-balance enhanced command in the system view to configure load balancing among the member interfaces based on source/destination IP addresses in IP headers. If this command is not configured, the Eth-Trunk member interfaces load balance packets based on source/destination IP addresses in GRE headers outside the IP headers. Because multicast packets of a private network are encapsulated with the same GRE header, all multicast packets are forwarded through the same member interface. Load balancing cannot be implemented in this case.
- If an Eth-Trunk has been configured as a multicast VPN loopback interface, do not use the MIB to perform other service configuration on the Eth-Trunk. If service configuration is performed, the multicast VPN loopback interface will become invalid or the service configuration may not take effect.
Run trunkport interface-type interface-number
A physical interface is added to the Eth-Trunk interface.
- A physical interface cannot function as a member interface of the multicast loopback interface if other services have been configured on the physical interface. It is recommended that you use idle interfaces (with no cables connected) as member interfaces.
- Repeat step 5 to configure multiple physical interfaces as member interfaces of the multicast loopback interface.