Wireshark-users: Re: [Wireshark-users] TCP Analysis Flags do NOT show DuplicateACK's & Retransmis
From: "Feeny, Michael \(GWM-CAI\)" <[email protected]>
Date: Wed, 25 Jun 2008 14:59:49 -0400

Thx for the QUICK response - this is an awesome forum!

The answer to one of your questions is:  *this instance of wireshark on
this particular system*

E.g., If I'm looking at the file where dupe ack's/retransmissions are
NOT reported, and then, within the same instance of Wireshark, I do an
Open of the other file, I now *do* see dupe ack's & retransmissions
being reported in that second file.

Regarding "tcp analysis" being turned off...  If I go to
Edit/Preferences/Protocols/TCP, the following options are CHECKED:

- Show TCP summary in protocol tree
- Validate the TCP checksum if possible
- Allow subdissector to reassemble TCP streams
- Analyze TCP sequence numbers

The rest of the options are UNCHECKED.  Is there anything else I should

I now know not to send screenshots :-)

If a small trace file is desired, would I simply add it as an attachment
to my email msg?

Thx again for the help!


Michael Feeny
Global Wealth Management Technology
Network and Security Integration
Office: 609-274-2761
Mobile:  484-995-1745
AOL IM: feenyman99
Pager:  888-merril0

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Sake Blok
Sent: Wednesday, June 25, 2008 2:03 PM
To: Community support list for Wireshark
Subject: Re: [Wireshark-users] TCP Analysis Flags do NOT show
DuplicateACK's & Retransmissions

On Wed, Jun 25, 2008 at 12:57:53PM -0400, Feeny, Michael (GWM-CAI)
> What is puzzling me is that Wireshark is NOT reporting the Dupe ACK's
> Retransmissions.  *I* am able to see them (28 packets in a row from
> side, with no data, and with identical sequence & ack numbers;  then,
> packet from the other side with the sequence number matching the 28
> ACK's, which packet had been sent previously by this server).  Not
> do these diagnoses not appear in the "Info" column of the Packet List,
> but, if I enter a Display Filter of "tcp.analysis.flags", not a single
> packet is displayed.

That sound like tcp analysis is turned off, could you have a look at
your TCP protocol preferences?

> This same version of Wireshark *is* displaying dupe ACK's and
> retransmissions, etc., for a *different* trace file, so it appears
> Wireshark's non-reporting of these conditions is related to this
> particular trace file.

The same *version* or *this instance of wireshark on this particular

> I've included a Wireshark screenshot, in case it's helpful.  I can
> down the PCAP to a small file, and send it, if that is also desired.

Please don't send screenshots to the list, they are big and provide much
less information that a small pcap file.

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