Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!proteon.com!jas
From: jas@proteon.com (John A. Shriver)
Newsgroups: comp.protocols.tcp-ip
Subject: high cost of routing
Message-ID: <8908291438.AA26094@monk.proteon.com>
Date: 29 Aug 89 14:38:36 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 19

Two possibilities:

1.  One of the host TCP implementations is hyper-sensitive to small
changes in the round trip time.  There will be an increase in
end-to-end delay passing through the router.  This could affect
various congestion control algorithms in the hosts (like the Nagle
algorithm). 

2.  Someone is dropping a packet.  It could be that the router is not
keeping up, or it could be that the router is sending faster than one
of the hosts can receive.  Many Ethernet interfaces have subtle "deaf
time" problems.

You might want to look at the TCP, IP, and device stats on the two
machines.  Unfortunately, until 4.3tahoe (?), the TCP stats were not
very detailed.

Alternately, you could use a Sniffer (or the like), and interpret the
TCP packets to see what's happening.