RFC 17 (rfc17) - Page 1 of 4

Some questions re: Host-IMP Protocol

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Network Working Group                                         J. Kreznar
Request for Comments: 17                                             SDC
Category: Informational                                   27 August 1969


                  Some Questions Re: HOST-IMP Protocol

1.  Automatic deletion of links, as indicated in BBN 1822, page 11,
    seems bad:

     a) Link use may be dependent upon human use of a time share
        terminal - indefinite time between messages.

     b) Program using link may be slow due to:

        i)  Busy HOST (many jobs)

        ii) Much local I/O and/or CPU time between messages - is it
            that, if a HOST's user fails to use a link for 15 seconds,
            the HOST network program must generate a dummy message
            merely to keep the link open?

2.  Steve Crocker, HOST Software, 1969 Apr 7, asks on page 2: "Can a
    HOST, as opposed to its IMP, control RFNM's?"  BBN, Report No. 1837,
    1969 Jul, says on page 2: "The principal function of the (IMP)
    program...includes...generating of RFNM's..."  What if an IMP
    generates an RFNM and then discovers it cannot, for some reason,
    complete timely delivery of the last received message to its HOST?
    This seems especially pressing since I don't recall seeing anywhere an
    IMP constraint upon HOSTs that they must accept incoming messages
    within some specified maximum time.

3.  A HOST has to be prepared to repeat transmissions of a message
    into network (see, e.g., Page 17, BBN 1822) therefore why the
            special discardable NOP message (Page 12, BBN 1822).

4.  "Arbitrary delays," middle paragraph, page 23, BBN 1822, seems
    inconsistent with automatic link deletion questioned in 1 above.
    Normally the times involved differ by many orders of magnitude but a
    high priority non-network HOST responsibility could delay next bit for
    a long time.

    1.  Abhi Bhushan, Proj. MAC         10.  Sal Aranda, SDC
    2.  Steve Crocker, UCLA             11.  Jerry Cole,  "
    3.  Ron Stoughton, UCSB             12.  John Kreznar,"
    4.  Elmer Shapiro, SRI              13.  Dick Linde,  "
    5.  Steve Carr, Utah                14.  Bob Long,    "
    6.  John Haefner, RAND              15.  Reg Martin,  "



Kreznar & Kahn
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