Ethereal-dev: Re: [Ethereal-dev] TCP/IP Retransmission

Note: This archive is from the project's previous web site, ethereal.com. This list is no longer active.

From: Guy Harris <gharris@xxxxxxxxx>
Date: Mon, 22 Mar 2004 11:38:14 -0800
On Mon, Mar 22, 2004 at 10:20:31AM -0600, Chula Bandara wrote:
> Hi i am using  Etereal Version 0.10.0a and this was very useful to me 
> solving connectivity issues with our Service Providers. Few days back i 
> had a similar problem that i see TCP retransmission but one of my 
> Service Provider did not those retransmissions. My SP was using Network 
> Associates Sniffer Pro Version 4.50.04. and i got some of  captured 
> files from the Sniffer. Surprisingly when i open those files with 
> Ethereal , it sees Retransmissions , Packet Losses , Duplicate ACks etc..
> 
> could this be a bug in Ethereal or the Sniffer

Perhaps there's a bug in Ethereal that causes it to claim a packet to be
a retransmission when it isn't one.

Perhaps there's a bug in the Sniffer that causes it to inject duplicate
packets into a capture.

Perhaps there's a bug in whatever tool your service provider uses to
find retransmissions that causes it *not* to claim a packet to be a
retransmission when it *is* one.  (Are they using the "expert" features
of the Sniffer?  If not, perhaps they should try that - I suspect it can
identify retransmissions.)

Or perhaps they're just looking at the captures to try to identify
retransmissions themselves, and not doing a sufficiently good job of it
to see them.