[bleonhardt@xxxxxxxxxxx]

Hi,

AFAIK, 


tcp uses windowing, so not every packet should be acknowledged - of 
course, a ACK of every packet / frame will slow down the connection as 
there's more traffic on the network than usual .. 

.. maybe a resize of the window-size could help .. try DrTCP ( just google 
for it ) to change the settings .. then restart your network ( 2k/xp ) or 
restart the pc/notebook.


-Alex

Bruno-Alexander Leonhardt
http://www.linux-vpn.de




ethereal-users-bounces@xxxxxxxxxxxx schrieb am 30.07.2004 13:43:22:

> Well, thanks very much for trying! Maybe someone else will come up with 
something?
> 
> Steve
> 
> -----Original Message-----
> From: ethereal-users-bounces@xxxxxxxxxxxx 
[mailto:ethereal-users-bounces@xxxxxxxxxxxx] 
> On Behalf Of Jim Hendrick
> Sent: Friday, 30 July 2004 9:35 PM
> To: 'Ethereal user support'
> Subject: RE: [Ethereal-users] Can you help me diagnose a performance 
problem?
> 
> Hmmm... Nothing obvious then. It sounds like the NIC (or something to do 
with 
> the NIC; possibly the driver, possibly the motherboard bus connections, 
etc. 
> etc.) is just slower on that box. 
> 
> Sorry, but I don't think I can be of much more help.
> 
> Jim
> 
> -----Original Message-----
> From: ethereal-users-bounces@xxxxxxxxxxxx 
[mailto:ethereal-users-bounces@xxxxxxxxxxxx] 
> On Behalf Of Steve
> Sent: Thursday, July 29, 2004 9:57 PM
> To: 'Ethereal user support'
> Subject: RE: [Ethereal-users] Can you help me diagnose a performance 
problem?
> Actually, the faster PC is the one that only ACKs every 2 segments. When 

> downloading from the Internet the slower one ACKs every segment 
(although 
> every 2 when transferring across the LAN). It seems to me as if when it 
ACKs 
> every segment it slows things down ? maybe the sender?s waiting for the 
ACK, 
> but on the faster PC things are more overlapped. Bit out of my depth 
here!
> 
> On the slow machine (a 1.8GHz Thinkpad laptop) I have a built-in NIC and 
a NIC
> in a docking station.  Both are slower than other machines, even much 
older 
> and slower laptops. All only have TCP/IP installed. I?ve also run the 
Thinkpad
> in safe mode (with network support) to make sure all the usual crap 
isn?t 
> loaded, and it behaves the same. Still at a loss!
> 
> Steve
> 
> -----Original Message-----
> From: ethereal-users-bounces@xxxxxxxxxxxx 
[mailto:ethereal-users-bounces@xxxxxxxxxxxx] 
> On Behalf Of Jim Hendrick
> Sent: Friday, 30 July 2004 11:36 AM
> To: 'Ethereal user support'
> Subject: RE: [Ethereal-users] Can you help me diagnose a performance 
problem?
> 
> Do you see the same ACK behavior for outbound from the slow PC? I am 
beginning
> to suspect that it has to do with that (since you seem to have 
eliminated all 
> the other likely areas).
> 
> Not sure why the "sender" would do this, but it almost looks like there 
is a 
> delay when the sender waits for the ACKs, and your "fast" PC is issuing 
an ACK
> for each packet so the transfer goes more quickly.
> 
> Not a great technical analysis admittedly. 
> 
> Have you looked closely at the inter-packet times when doing LAN 
transfers? I 
> am still thinking there may be something with the driver or the network 
stack.
> Sayyy... What do you have installed/enabled on these machines? Does the 
slow 
> one have more services or protocols enabled? (like IPX/SPX/NetBIOS ?) It 
used 
> to be (older Windows crap) that the *order* in which you configured them 
made 
> significant performance differences. It is much better w/ 2000 & XP, but 
still
> an area you might look for differences between the machines.
> 
> If the network connections are configured the same (and you said they 
were all
> XP Pro boxes) then maybe the driver or one card is better/worse than the 

> other. Is one a "motherboard" NIC and another on a daughter card?
> 
> More stuff to check.
> 
> Jim
> 
> 
> 
> 
> -----Original Message-----
> From: ethereal-users-bounces@xxxxxxxxxxxx 
[mailto:ethereal-users-bounces@xxxxxxxxxxxx] 
> On Behalf Of Steve
> Sent: Thursday, July 29, 2004 8:06 PM
> To: 'Ethereal user support'
> Subject: RE: [Ethereal-users] Can you help me diagnose a performance 
problem?
> Thanks for the comments, Jim. I?ve waited a little while before replying 
in 
> the hope there might have been other responses.
> 
> With regard to the physical layer, I have physically put the fast PC on 
the 
> same cable as the slow PC to check, and it is still faster, so that?s 
not it.
> 
> I tested some transfers across the LAN. Inbound to the slow PC is always 

> slower. Outbound is OK. Although an Ethereal trace of a ?slow? inbound 
> transfer does show one ACK for every 2 segments when transferring across 
the 
> LAN, and the difference in speed is not so marked as when downloading 
from theInternet.
> 
> Steve 
> 
> 
> -----Original Message-----
> From: ethereal-users-bounces@xxxxxxxxxxxx 
[mailto:ethereal-users-bounces@xxxxxxxxxxxx] 
> On Behalf Of Jim Hendrick
> Sent: Thursday, 29 July 2004 3:36 PM
> To: 'Ethereal user support'
> Subject: RE: [Ethereal-users] Can you help me diagnose a performance 
problem?
> 
> Hmmm. Not sure why the window sizes are different or the ACK policies 
differ. 
> 
> Does anyone know how XP handles selective ACK? It seems like the one 
that is 
> ACKing multiple packets is faster (although this is probably not the 
reason 
> for the difference).
> 
> Another basic Q. Is the physical layer identical for both (cables, 
network 
> drops, patch panels if any, switches, etc. etc.)
> 
> Can you try a file transfer within your own network? Perhaps even 
between a 
> "fast" and "slow" machine (in each direction) or from both to (and from) 
a 3rd machine.
> 
> This may not point out anything, but it will be a more controlled test. 
> 
> It may be as simple as a physical or a software (card / driver) issue, 
but 
> what the *reason* behind it is not obvious.
> 
> 
> -----Original Message-----
> From: ethereal-users-bounces@xxxxxxxxxxxx 
[mailto:ethereal-users-bounces@xxxxxxxxxxxx] 
> On Behalf Of Steve
> Sent: Wednesday, July 28, 2004 10:58 PM
> To: ethereal-users@xxxxxxxxxxxx
> Subject: [Ethereal-users] Can you help me diagnose a performance 
problem?
> Hi, first time on the list and not exactly a network specialist, so bear 
with me!
> 
> I?ve been struggling with a performance problem where Internet downloads 
from 
> one machine tend to be about 20% slower than those from other machines 
on the 
> network (all Win XP Pro). All settings I can think of are identical, and 
the 
> ?slow? machine is about the fastest on the network in all other 
respects. 
> Ethereal captures do show up some interesting differences. Traffic from 
a 
> ?slow? machine looks like this (hope it formats OK):
> 
>   15818 23.220614   144.135.23.54         192.168.0.5           TCP 4000 

> > 3091 [ACK] Seq=11378574 Ack=0 Win=7086 Len=1446
>   15819 23.220806   192.168.0.5           144.135.23.54         TCP 3091 

> > 4000 [ACK] Seq=0 Ack=11380020 Win=64000 Len=0
>   15820 23.229900   144.135.23.54         192.168.0.5           TCP 4000 

> > 3091 [ACK] Seq=11380020 Ack=0 Win=7086 Len=1446
>   15821 23.230082   192.168.0.5           144.135.23.54         TCP 3091 

> > 4000 [ACK] Seq=0 Ack=11381466 Win=64000 Len=0
> 
> Each ACK acknowledges the segment before it, and has a time to ACK the 
segment
> of around .00018 seconds.
> 
> Traffic from a "fast" machine looks like this:
> 
>    4095 5.885410    144.135.23.54         192.168.0.4           TCP 4000 

> > 1101 [ACK] Seq=3865158 Ack=0 Win=6810 Len=1446
>    4096 5.886590    144.135.23.54         192.168.0.4           TCP 4000 

> > 1101 [ACK] Seq=3866604 Ack=0 Win=6810 Len=1446
>    4097 5.886617    192.168.0.4           144.135.23.54         TCP 1101 

> > 4000 [ACK] Seq=0 Ack=3868050 Win=64000 Len=0
>    4098 5.887665    144.135.23.54         192.168.0.4           TCP 4000 

> > 1101 [ACK] Seq=3868050 Ack=0 Win=6810 Len=1446
>    4099 5.889292    144.135.23.54         192.168.0.4           TCP 4000 

> > 1101 [ACK] Seq=3869496 Ack=0 Win=6810 Len=1446
>    4100 5.889346    192.168.0.4           144.135.23.54         TCP 1101 

> > 4000 [ACK] Seq=0 Ack=3870942 Win=64000 Len=0
> 
> Each ACK again acknowledges the segment before it, but only every second 

> segment gets ACK'd. Also the time to send the ACK is now .00003 (much
> quicker). I also don't know why the sender's Win size is different in 
the 2 cases.
> 
> Can anyone point me in the right direction here? Thanks.
> 
> Steve
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