dial-in lines being held for "days"

[jrv]

This is my reaction to the flurry of messages about whether there is 
some way to limit dial line use. I will try to summarize what I have 
understood and respond to it.  Perhaps we can push the discussion a
little further.

There have been a lot of busys, especially on the 9.6 kb (as oppossed to
the 19.2 kb) hunt groups.  These are the lines that are used for framed
protocols such as PPP, SLIP, SLFP, and MCP/PCTIE.

Problems have occurred at UM, Wayne State and other locations.  16 new
modems have been installed at UM and the problem has been reduced
dramatically. (At least for the time being)

A few specific cases have been identified where someone connected for a
day or more and had no traffic after some initial time (a couple hours
perhaps).  

A sense of fair play indicates that if you are not using the line, and
someone else is waiting, then you should give up the line.  For those
who don't give the line up, it has been suggested that they be
disconnected after some period of inactivity.

There has been much discussion about how long to wait before
disconnecting someone, and whether it should only be disconnected if the
line is inactive, or if disconnect should happen after a fixed time
regardless of activity level.  Disconnecting after inactivity would
catch those who connect then forget to disconnect (easier with Packet
Driver suppported protocols).  However it would be easy to force some
periodic activity, so this would not catch the person who is dialing in
and holding a connection so it will be available when needed.  This
would presumably only be caught by some fixed time disconnect.

Variations on this propose that auto disconnect be done if the caller is
not authorized (i.e. anonymous).  These callers could connect for some
time - say two hours - as anonymous, then be disconnected.  This limits
the long term abuse to those who help support the cost of the modems.

A further variation suggested is to charge for use after some time.
This would allow authorized users to stay on as long as they want, but
be charged after the initial time period.  The charges would then be
used to provide equipment.  At the extreme end of this it would be
possible for someone to pay for a line, modems, and a piece of the
Terminal Server, and have a private dial in line.  This could be cheaper
than having a leased line, and would work more like a NetBlazer.