From: John Traynor
[mailto:John.Traynor@xxxxxxx]
Sent: Monday, June 04, 2007 10:52
PM
To: rvolz@xxxxxxxxxxxxxxx;
'Community support list for Wireshark'
Subject: RE: [Wireshark-users] TCP
Dup Ack
Pardon my intrusion, but I've had a very
similar problem within out small office network. Are you certain that the
problem lies on the internet side? I have spent hours trying to track
down the issue and have now concluded that it is an errant driver on one
machine that is causing the problem. Initially I suspected several other
things, but persistent testing has pinpointed our problem to a single PC.
File copies of a 100MB file FROM that machine to any other machine takes well
over 5 minutes. In safe mode with only two nodes active that same copy
takes about 15 seconds. I have additional testing ahead to try to
identify the specific driver, but I believe the end is in sight and its not
what I originally believed it would be.
Good luck.
From: wireshark-users-bounces@xxxxxxxxxxxxx
[mailto:wireshark-users-bounces@xxxxxxxxxxxxx] On Behalf Of Roland Volz
Sent: Monday, June 04, 2007 1:11
PM
To: wireshark-users@xxxxxxxxxxxxx
Subject: [Wireshark-users] TCP Dup
Ack
I have a couple of customers that have
been complaining of issues on their circuits, an issue that causes them to have
problems with large file transfers. The only noteworthy problems in their data
streams seem to be TCP Dup Acks – I’ve seen as many as sixty, or
over a hundred, in file transfers of 100 MB test files. However, as near as I
can determine, these errors are being introduced in the Internet, outside of
our network (the customers use VPNs over internet circuits with major carriers
for these file transfers).
As I said, we’ve tested our own
network thoroughly, but I’m at a loss as to where to go with this issue.
Obviously, telling the customer, “It’s not our fault” is
unacceptable, as that doesn’t move them any closer to error-free file
transfers. On the other hand, I’m not sure where to tell the
carriers’ help desk technicians to look for the source of this issue. Has
anyone seen this before on Internet circuits, and is there some way I can use
Wireshark to help pinpoint the issue more specifically than telling the
carrier, “It’s in your cloud”?
Thanks,
Roland Volz
Network Engineer
Data Access/Datapatch,
Inc.
40 Eisenhower Drive
Paramus, NJ 07652-1404
(201) 843-5468 x7032
www.Data-Access.com
