To be honest I think both work now, it used to be VC Mux only but I think that you can select either now although its a while since I messed with it.
It was mainly LLC back in the day, but as they installed newer equipment etc... seems both can be used.
However I am unable to connect if I force LLC headers, might just be my router been fussy.
VC-MUX will give you a slightly quicker latency as it has smaller overheads.