Mark,
if your provider gives you a set of VLANs, you can translate your BVIDs to those with use of IS-IS logical interface. Each link (hub & spoke or mesh point-to-point) shall be a pair of logical interfaces that map SPBM BVIDs to carrier VIDs.
The entire magic is here:
router isis
logical-intf isis 1 vid 101,102 primary-vid 101 port 1/1 name l2tun_1to3Where
1 is just logical interface ID and
vid is a list of carrier VIDs to have your BVIDs translated to. You can have
mlt instead of a
port if applicable.
You can then test with:
show isis logical-interface
show isis interface
show isis adjacencies
Please remember of the MTU, 1544B minimum at your provider.
Please remember to have unique VIDs for each port/MLT.
Further details can be found on pages 42-43 of this doc:
https://documentation.extremenetworks.com/VOSS/SW/71x/9035537_ConfigFabBasicsVOSS_7.1_CG.pdf
Hope that helps,
Tomasz