Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!unsvax!jimi!herbert!doug
From: doug@herbert.uucp (Doug Phillipson 5-0134)
Newsgroups: comp.protocols.tcp-ip
Subject: Bridges slow down over time.
Message-ID: <1990Jan13.230551.6884@herbert.uucp>
Date: 13 Jan 90 23:05:51 GMT
Reply-To: doug@jimi.cs.unlv.edu (Doug Phillipson 5-0134)
Distribution: usa
Organization: EG&G, Energy Measurements
Lines: 27

Running SUNOS 4.0.3

   -----     ----     ---           ---     ----     -----
  |     |___|    |___|   |         |   |___|    |___|     |
  |     |   |    |   |   |  TELCO  |   |   |    |   |     |
   -----     ----     ---           ---     ----     -----
    Sun4    Bridge   Modem         Modem   Bridge     SUN4

        The bridges are Advanced Computer Communications
Model# ACS4030, the modems are NEC 9631 running in synchronous
mode at 9600. The problem:

        When transfering a file between the SUNS (or any other host).
The throughput gradually decreases over time. I.E transferring a one
meg file starts out good then in a little while the modem activity
decreases and I start getting "NFS host not responding" messages
(if using cp with a mounted file system). Or if using rcp the through
put just goes to heck. I have noticed that if lots of requests are
traversing the bridges (lots of separate rcp's or cp's on a mounted NFS)
the throughput stays good. Its as if the bridges like lots of parallel
traffic. Then when most of the rcp's are done the traffic trails off
again and the one or two unfinished copy commands go to crap.

Has anyone seen this problem?
Generally these bridges work well but this confuses me.

Douglas Phillipson (EG&G)