🚀 go-pugleaf

(interactive messaging vs. Internet services to do same)

It's my understanding that BITNET uses a type-of-service (TOS)
queueing approach to speed "interactive" messages along
their way while ordinary mail traffic gets a slower
store-and-forward approach.

There is a TOS queuing facility that discriminates between interactive
traffic (telnet, rlogin) and bulk traffic (NNTP, SMTP, FTP data) in
Van Jacobsen's "compressed SLIP" package for running IP links over
slow dial-up type lines on the order of 9600 bits/second -- it
improves perceived performance considerably for normal use.  Any site
that's converting over to IP that uses data links in this range should
specify the availability of such priority queueing to make sure that
they can cope sensibly with a mix of bulk and interactive traffic.

I'm not sure what the state-of-the-art type of service
markings are, but here's an indication of how they
are specified in IP (RFC 791) as an example of the
sorts of factors to be balanced.

  Type of Service:  8 bits

    The Type of Service provides an indication of the abstract
    parameters of the quality of service desired.  These parameters are
    to be used to guide the selection of the actual service parameters
    when transmitting a datagram through a particular network.  Several
    networks offer service precedence, which somehow treats high
    precedence traffic as more important than other traffic (generally
    by accepting only traffic above a certain precedence at time of high
    load).  The major choice is a three way tradeoff between low-delay,
    high-reliability, and high-throughput.

      Bits 0-2:  Precedence.
      Bit    3:  0 = Normal Delay,      1 = Low Delay.
      Bits   4:  0 = Normal Throughput, 1 = High Throughput.
      Bits   5:  0 = Normal Relibility, 1 = High Relibility.
      Bit  6-7:  Reserved for Future Use.

         0     1     2     3     4     5     6     7
      +-----+-----+-----+-----+-----+-----+-----+-----+
      |                 |     |     |     |     |     |
      |   PRECEDENCE    |  D  |  T  |  R  |  0  |  0  |
      |                 |     |     |     |     |     |
      +-----+-----+-----+-----+-----+-----+-----+-----+

        Precedence

          111 - Network Control
          110 - Internetwork Control
          101 - CRITIC/ECP
          100 - Flash Override
          011 - Flash
          010 - Immediate
          001 - Priority
          000 - Routine

    The use of the Delay, Throughput, and Reliability indications may
    increase the cost (in some sense) of the service.  In many networks
    better performance for one of these parameters is coupled with worse
    performance on another.  Except for very unusual cases at most two
    of these three indications should be set.

  Type of Service

    The type of service (TOS) is for internet service quality selection.
    The type of service is specified along the abstract parameters
    precedence, delay, throughput, and reliability.  These abstract
    parameters are to be mapped into the actual service parameters of
    the particular networks the datagram traverses.

    Precedence.  An independent measure of the importance of this
    datagram.

    Delay.  Prompt delivery is important for datagrams with this
    indication.

    Throughput.  High data rate is important for datagrams with this
    indication.

    Reliability.  A higher level of effort to ensure delivery is
    important for datagrams with this indication.