This article will help you add a logical unit from an interface to a VPLS instance, while the rest of the units remain separate and are running Multiple Spanning Tree Protocol (MSTP).

Acronyms used:

IFL= Logical Interface (i.e., unit ge-0/0/0.40)
IFD= Physical Interface (i.e., ge-0/0/0)
MSTP= Multiple Spanning Tree Protocol
VPLS= virtual private LAN service

If an IFL is attempted to be added to a VPLS instance while the IFD is still part of MSTP, then the following error will be retrieved when commiting the changes:

JTAC@MX80# commit check error: STP for interface ge-0/0/0.40 must be configured within a routing-instance of type layer2-control. Currently its configured as part of instance default. This is incorrect. error: configuration check-out failed

If an IFL needs to remain separate from the rest because it will serve another purpose, such as another instance of the router, in this case VPLS, then the rest of the units will also need to be isolated. This is so the router will still be able to track and perform Layer 2 Control Protocol features such as nonstop bridging or Layer 2 Tunneling Protocol (L2TP).

Remove the IFD from the MSTP configuration currently belonging to the default/master instance of the router:

And then add it to a layer2-control routing instance, so the router can have it isolated:

Final configuration might look like this:

And the commit will finally succeed:

Note that the ifl in question is ge-0/0/0.40, which needs to be part of the VPLS routing instance; the rest of the IFLs are still running encapsulation vlan-bridge, and might be running MSTP on a separate part of the network.

Keep in mind that whenever you want to check on MSTP information or statistics, you will now need to reference the configured layer2-control instance; otherwise no information will be retrieved: