Wireshark · Wireshark-users: Re: [Wireshark-users] Windows XP Pro and ICMP Source Quench

[Martin Visser <martinvisser99@xxxxxxxxx>]

A client sending a RST for other than the application or end-user wanting to end the session is pretty severe behaviour. If you client is shutting the windows to 0, prior to this,  the server should stop sending. So assuming client buffer eventually empties, all should be good.

Sounds like the app is basically is not coping with the given network environment.

Regards, Martin

MartinVisser99@xxxxxxxxx

On Tue, Jun 2, 2009 at 12:04 PM, Merton Campbell Crockett <m.c.crockett@xxxxxxxxxxxxxx> wrote:

Martin:

The Online Communicator 2005 client sending TCP resets and TCP acknowledgements with the TCP window set to 0 to the Live Communications Server 2005 server.  The former response seems to occur when the the received packet contains more data than can be accepted into the current TCP window.

Well, it has been nearly a decade since I worked in environments where the TCP/IP traffic was being routed over multiple satellite hops.  

On 31 May 2009, at 21:34:15, Martin Visser wrote:

Merton,

You haven't detailed what aspect leads you to the conclusion the client isn't keeping up. At a guess if you are referring to dropped video frames (for real-time conferencing and the like ) because of lack of client CPU/graphics capability, then telling the server the server to slow down isn't going to do anything for you. This is no difference for say a VoIP/internet telephony setup where if you experience congestion there is little else to do other than play silence. The only other thing to do is during setup phase where you might choose a lower frame rate/resolution which might reduce the network load and/or CPU load for encoding/decong the media.

And as Ronnie correctly says, ICMP source quench might still live in networking text books, but no one has used it in real life for a good decade or so.

Regards, Martin

MartinVisser99@xxxxxxxxx

On Mon, Jun 1, 2009 at 12:00 PM, Merton Campbell Crockett <m.c.crockett@xxxxxxxxxxxxxx> wrote:

Using various Wireshark's various tcp.analysis expressions I've
discovered that it is not uncommon for the Live Communications Server
2005 to transmit data to a Windows XP client faster than the latter
can transfer data to the application.  It's unclear whether its simply
that Office Communicator 2005 can't keep up or if it is the result of
other activity on the client system.

Does the Windows XP TCP/IP protocol stack transmit ICMP Source Quench
packets when it is in danger of exhausting its buffer space?

I didn't find any ICMP Source Quench packets in the traffic that I had
captured.  If it doesn't, everything is fine. :\  If it does, I may
need to search for a network device that is overly zealous in
filtering ICMP packets. :-(



Merton Campbell Crockett
m.c.crockett@xxxxxxxxxxxxxx



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Merton Campbell Crockett

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