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From: evan@is.rice.edu (Evan R. Wetstone)
Newsgroups: comp.dcom.sys.cisco
Subject: Re: Terminal server hangs
Message-ID: <35119@boulder.Colorado.EDU>
Date: 16 May 91 08:53:05 GMT
Sender: daemon@boulder.Colorado.EDU
Lines: 24

We have experienced delays as well.  They only appear between our terminal
server and our Sun 4/490.  It does not appear to happen between the terminal
server and any of our slower machines (3/280's, 4/65's, 4/280's).  I can
pretty much reproduce the problem at will.


Analysis with a Sniffer shows that when the terminal server advertises a
relatively small TCP window (800-900 bytes) *AND* the 4/490 actually fills
the window completely, there is about a 5 second delay.  Looks kind of like
this:

Terminal server acks with window size of 870,
Sun responds immediately with 7 bytes
Terminal server acks with window size of 863,
Sun responds 5 seconds later with 863 bytes......


Maybe it is a SunOS bug that appears when it has to fragment a send buffer
to a smaller size than it wants to use?

--
Evan Wetstone
Network Support
Rice University