Re: [Sheflug] [OT, slightly] Parallel port network interfaces?

["Stephen J. Turnbull" <nospam [at] sk.tsukuba.ac.jp>]

>>>>> "Chris" == Chris J/#6 <sixie [at] nccnet.co.uk> writes:

    >> Whatever is reporting the transfer is stuffing the data in a

My bad; the buffer-stuffing can happen at a lower level of course.

    >> buffer, then waiting until the buffer is empty, reporting the
    >> whole transfer as if it was instantaneous, and then repeating.

    Chris> As I said - switching all PPP compression options off boost
    Chris> performance quite a chunk (to 2k/sec or faster).

Well, your protocol stack is quite deep here:

      FTP - probably does some buffering, but its reports should
            account for that
      TCP - possibly does some buffering since it's stream-oriented
      IP  - datagram service, no buffering
      PPP compressor - surely does buffering, otherwise what's the point?
      PPP - surely does buffering

Also, many PPPs have problems with compression, I don't know why --
you'd think they'd fix that quickly; it's not like there aren't a
bunch of good PPP implementations around.  Seems unlikely with
OpenBSD, which I gather is your other end?  Is the OpenBSD PPP up to
date?

But I guess all that is moot:

    Chris> I've thrown tcpdump on the link to see what's going on and
    Chris> at those delays absolultely no traffic passes between the
    Chris> machines. That burst comes, gets written to disk, then for
    Chris> some reason, either proftpd or the network protocols just
    Chris> decide to stop traffic for a couple of minutes or so.

Hmm.  Sounds like somebody is not getting the acks they want.
Firewall or router problems?  Seems unlikely, but....  Flakey lines?
Old laptop, maybe it's got a really sucky serial chip?

Look at the LCP trace for the PPP-level ACKs and stuff, maybe.

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