He asked for the congestion window.
not the advertised window.
On 11/15/05, Andersen Jens Elmo <jens.elmo.andersen@xxxxxxxxxxx> wrote:
> Uh ???
>
> The TCP window size is present in every single TCP packet.
> As such you should be able to extract the value and plot it.
> However, I dont know if Ethereal can do it
>
> The receiving station will sent the windowsize telling how much data the
> transmitting station can send with out waiting for an acknowledge.
> Typical 16K byte
> It will decrease the window size in face of packet loss to adjust the
> sender to the available bandwith.
> Normally you dont need to worry about this
>
> It will also decrease if the reciever runs out of buffer space.
> In this case, you should rather fix the problem than monitor.
> No need to plot a graph if you see this behgaviour - use more CPU power
> and more memory in the server.
>
> The initial value can vary from machine to machine, and it also depends
> on wether you use "slow start"
> In "slow start" the server starts up with a fairly small window and
> increases the size until packets starts getting dropped. This is the
> best behaviour seen from the network.
> Without "slow start" the server will start out with maximum windowsize
> which will give the user the best performance but can load the network
> for a short period.
>
>
> Regards
>
> Jens Elmo
>
>
> -----Original Message-----
> From: ethereal-users-bounces@xxxxxxxxxxxx
> [mailto:ethereal-users-bounces@xxxxxxxxxxxx] On Behalf Of ronnie
> sahlberg
> Sent: 15. november 2005 09:43
> To: Ethereal user support
> Subject: [Ethereal-users] Re: Plotting TCP Congetion Window evolution
>
> No,
>
>
> it is not possible using any tool.
>
>
> the congestion window is an artificial limit imposed internally by the
> TCP sender.
> its size is not stored inside the packet.
> neither is it possible to determine it by looking at a trace.
>
>
> different implementations also use different/tweaked methods how they
> manage the congestion window internally making it more difficult.
>
>
>
> you really need to know the exact algorithms in great detail about the
> exact specific implementation of the host sending the data in order to
> be able to "guess" what the congestion window is set at at a specific
> point in time.
>
>
>
>
>
> On 11/15/05, Prasad Kularatne <kularatn@xxxxxxxxxx> wrote:
> > Hi folks,
> >
> > Does anybody know whether it is possible to plot the TCP Congestion
> > Window evolution using Ethereal?
> >
> > Please advise. Thanks.
> >
> > Good Luck!
> > Prasad
> >
> >
>
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