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From: BILLW@mathom.cisco.com (WilliamChops Westfield)
Newsgroups: comp.dcom.sys.cisco
Subject: Re: Terminal server hangs
Message-ID: <35151@boulder.Colorado.EDU>
Date: 17 May 91 00:54:53 GMT
Sender: daemon@boulder.Colorado.EDU
Lines: 29


    We have seen this type of behavior occasionally on other TCP/IP
    implementations.  We have never completely resolved the problem
    however, the best guess is that it is related to the way a particular
    TCP/IP implementation handles calculation of expected transmission
    delays and how agressive it is in performing retries when a 
    response is not received in the expected amount of time.

    We have found 3COM telnet terminal server boxes to be relatively
    agressive in their retransmissions and we don't normally experience
    this phenomenon when telneting to their boxes.  However, we have
    seen these types of delays occasionally when telneting to some
    host based telnet implementations.

Hmmph.  The cisco terminal server's TCP uses you basic Karn/Jacobson
"network-friendly" exponential backoff algorithm, but this should not
result in significant delays unless something else is causing the
packets to be lost...


    It is a very hard problem to track down.

It's very frustrating - all the tools are there - the cisco practically
gives you a sniffer in every box, but to debug problems with durations
of <2 minutes, you pretty much have to be sitting at the console waiting
for it to fail.  Most people have better ways to spend their time.

BillW
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