[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[ih] ARPAnet Type 3 packets (datagrams)

    > From: "Bernie Cosell" <bernie at fantasyfarm.com>

    > IMPs *only* buffered packets at the modem-output queue. There was
    > no source-IMP buffering of data for the destination-IMP.

The 1972 FJCC paper does seem to indicate that this was not true of
single-frame messages, viz (pg. 743):

  "We minimize the delay for a short message by transmitting it to the
  destination immediately while keeping a copy in the source IMP. If
  there is space at the destination, it is accepted and passed on to a
  Host and a RFNM is returned; the source IMP discards the message when
  it receives a RFNM."

Did this continue to be the case, do you recall?

    >> a host was allowed to have up to 8 packets 'in flight' to a given
    >> destination at a time (basically - there are more details).

    > I don't think that hosts knew about packets

Apologies all, I was not sufficiently precise in my terminology; I was using
"packet" in the modern sense (in part because I'd just been looking at the IMP
interface code in the MIT router code :-), not in the old 'IMP subnet
transmission unit' sense.

(That's partly why I've started using the neologistic term 'frame' for the
IMP-IMP things, because that term is not ambiguous; I retain 'message' for the
host-host things, as it is also not ambiguous.)