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primary (Virtual Tunnel in Routing Instances)


Hierarchy Level


In a multiprotocol BGP (MBGP) multicast VPN (MVPN), configure the virtual tunnel (VT) interface to be used as the primary interface for multicast traffic.

Junos OS supports up to eight VT interfaces configured for multicast in a routing instance to provide redundancy for MBGP (next-generation) MVPNs. This support is for RSVP point-to-multipoint provider tunnels as well as multicast Label Distribution Protocol (MLDP) provider tunnels. This feature works for extranets as well.

This statement allows you to configure one of the VT interfaces to be the primary interface, which is always used if it is operational. If a VT interface is configured as the primary, it becomes the nexthop that is used for traffic coming in from the core on the label-switched path (LSP) into the routing instance. When a VT interface is configured to be primary and the VT interface is used for both unicast and multicast traffic, only the multicast traffic is affected.

If no VT interface is configured to be the primary or if the primary VT interface is unusable, one of the usable configured VT interfaces is chosen to be the nexthop that is used for traffic coming in from the core on the LSP into the routing instance. If the VT interface in use goes down for any reason, another usable configured VT interface in the routing instance is chosen. When the VT interface in use changes, all multicast routes in the instance also switch their reverse-path forwarding (RPF) interface to the new VT interface to allow the traffic to be received.

To realize the full benefit of redundancy, we recommend that when you configure multiple VT interfaces, at least one of the VT interfaces be on a different Tunnel PIC from the other VT interfaces. However, Junos OS does not enforce this.


If you omit this statement, Junos OS chooses a VT interface to be the active interface for multicast traffic.

Required Privilege Level

routing—To view this statement in the configuration.

routing-control—To add this statement to the configuration.

Release Information

Statement introduced in Junos OS Release 12.3.