There are at least a few ways to accomplish
this, depending on what you want exactly.
You can use Legacy DDR, and configure everything
under the physical PRI interface. You enable MPPP
there, and if the client requests MPPP it will be
negotiated. If you want to limit some users to one
connection, you can use either AAA or the "user-maxlinks"
option under the local username command.
If you want to use Dialer Profiles such that every
user has their own profile, there will be more to the
configuration but this is possible, too. The question is
one of binding inbound calls, however; if CLID is being
delivered, then you can bind with the
"dialer-caller" command and only configure MPPP on
those dialer interfaces (dialer profiles) that you want
MPPP enabled; on all others, and on the physical
interfaces, you do NOT enable MPPP. If CLID is not always
available, then you will have to bind on the authenticated
username, which means you have to enable MPPP on the
physical interface. This means that you would have to limit
the number of connections per-profile (since anyone
can have MPPP negotiated now) with the command
"ppp mult link max" command.
I would suggest you use the first solution; it's easier
to maintain.
