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Wireshark-users: [Wireshark-users] Question Regarding Suspected TCP Expert Problem

From: "Fischer, Sean" <Sean.Fischer@xxxxxxxxxxx>
Date: Wed, 6 Jan 2010 11:40:13 -0600

I have a number of captures within which the Wireshark expert indicates hundreds of TCP Previous Segment Lost and TCP ACKed Lost Segment warnings.  This is reflected both within the decode window on the packet Info as well as in the Expert Info dialog boxes.  A cursory review of the TCP data seems to confirm that the sequence numbers are correct.

 

I have found that going into preferences and toggling (both on-to-off and off-to-on) Relative Sequence Number and Window Scaling removes the expert info warnings.  Reopening the file recreates the warnings until toggling again.

 

I also found that saving an affected TCP stream out of the capture into its own cap file will cause Wireshark not to issue the warnings.

 

The capture does include the initial three way handshake of the TCP stream in question.  I have no reason to think any packets are not being captured, and the capture is being taken on a dedicated sniffer box with dedicated sniffing NICs on a mirrored switchport.  The complete capture is around 8MB.  I am using Wireshark 1.2.5 (SVN Rev 31296).

 

Are there any bugs related to this?  Any other helpful suggestions?

 

Thanks,

 

Sean