paul shields wrote:
One question I have is how does tethereal deal with retransmissions when using this statistics mode.
Does it:
1) Count every packet regardless of sequence numbers
2) not count the retransmitted packet
3) Not count the original packets, just the last instance of the sequence number
The statistics module in tethereal has no concept of "retransmissions"
of any kind (TCP, RPC, etc). It counds number of frames and bytes
matching the filter presented to it during any given time period (in my
example no filter was provided, in which case ALL packets matched the
statistics filter).
It seems that if it does 1 or 2, than it is not a true measure of throughput but rather of how much data was sent. Only the third method would give you something closer to what really made it through.
It depends on what you mean by "throughput", I suppose. If you're
trying to measure the total number of bytes passed between two hosts or
the utilization of a particular link, then I'd say it can accurately
measure "throughput". If you mean the amount of "data" in some
encapsulated stream, like a TCP payload, the contents of an NFS file
transfer, etc., then it will not give you this information.
This of course more significant when the capture is on the same network as the sender and not at the receive point.
I'm not sure that it's any MORE significant one way or another - one
should ALWAYS be aware of the placement of a network capture device when
analyzing traces. However, I think you're assuming that the only
throughput statistics I could interested in is the amount of some kind
of "user data" that actually passed between two hosts, in which case I
think it could be "more significant" to place the network capture device
at either end of the conversation, or at any one of multiple points
along the path of the conversation, depending on what I'm looking for.
-----Original Message-----
From: Ian Schorr [mailto:[EMAIL PROTECTED]
Sent: Thursday, July 10, 2003 2:10 PM
To: Raghu Ram Jakkampudi
Cc: [EMAIL PROTECTED]
Subject: Re: [Ethereal-users] Throughput
Ah, noticed you said "numerically", in which case you may have been
looking for something more like this:
From a command-line,
"tethereal -r filename.cap -R unmatched.display.filter -z io,stat,1"
where "filename.cap" is the trace file that you want to generate
statistics from, "unmatched.display.filter" is a display filter that no
frame in the trace (this is to supress the decoding of packets and
display only statistics. I never work with Token Ring, so I usually use
"-R tr" here), and "1", in this case, is the amount of time, in seconds,
of each sample.
In this case, tethereal will generate a set of bytes/sec and frames/sec
statistics that I can parse, import into and manipulate with
Excel/OpenOffice Spreadsheet, etc.
You can find more information about statistics generation with tethereal
in the tethereal man page.
If this isn't what you're looking for, can you provide more details on
what you're trying to do?
Ian
Ian Schorr wrote:
Are you looking for something like this?
Go to Tools->Statistics->IO->IOStat
Change Frames/Tick to Bytes/Tick
Change Tick Interval to the interval that you want.
Ian
Raghu Ram Jakkampudi wrote:
Hi
I was wondering if Ethereal can display the throughput
statistics,like the number of bytes that are transferred per second
numerically.
Please let me know how if it can do it.
Thank you
Raghu
--
Computer Science Dept.
University of Alabama in Huntsville
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