MPP = Ascend's Multilink Protocol Plus (aka: MP+)
This is backward compatible with MP.
MP = Multilink Protocol
For our RadiusNT settings (dial-up customers), we use Framed-Protocol = MP
and we've never had a problem (Ascend Max 40xx units). For that matter, we
originally had it set to MPP and that worked fine also. If you're using
Max 40xx, only 5.0Ai4 (and newer Incremental releases) support MP for
dial-up customers. The Patch releases never supported it. Now that 6.0.0
is out, I'm assuming that MP/MPP is supported for dial-up customers, though
I haven't tested MP using 6.0.0 yet.