RE: TCP Window Optimization with LFN.

Windows 2008 does some of the stuff you are wanting to do automatically as
does 2003 though. Are you using the same application to transfer the files?
If the app socket code doesn't have the option set for scaling, it wont be
used in 2003 from what I remember. I don't remember what you could set
globally/per interface/code in app per o.s. But generally you got more fine
grain control the newer the os and usually you had to ask the dev's to
re-write socket code in the older o/s'es.

New Networking Features in Windows Server 2008 and Windows Vista
http://technet.microsoft.com/en-us/library/bb726965.aspx
TCP Receive Window Auto-Tuning
http://technet.microsoft.com/en-us/magazine/2007.01.cableguy.aspx

Performance Enhancements in the Next Generation TCP/IP Stack
http://technet.microsoft.com/en-us/library/bb878127.aspx
Microsoft Windows Server 2003 TCP/IP Implementation Details
http://www.microsoft.com/en-us/download/details.aspx?id=13902

try using iperf and or ttcp to test (best to do iperf to iperf from end
stations though). Have you taken any captures to see what flags are set on
the tcp headers between the hosts to see what is being negotiated?

Something sounds fishy about changing the tcp window size on a router? So if
you had 1000 tcp clients going through the router, you would need to reserve
8GB of RAM for the buffers on the box for your 8MB buffer? That doesn't
sound right. The router/switch can already handle multi gigabit traffic. I
understand what you are trying to accomplish, I don't think its done with a
router. Does that command make a router reserve 8MB buffer for each http tcp
request from a client for a 10KB web page?

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of JB
Poplawski
Sent: Thursday, August 16, 2012 4:37 PM
To: Joseph L. Brunner
Cc: Dan Shechter; ccielab_at_groupstudy.com
Subject: Re: TCP Window Optiimization with LFN.

TAC is having me give this a whirl.

Global

ip tcp window-size 8625000

Config on L2 Interfaces

hold-queue 4096 in

hold-queue 4096 out

I calc-ed the estimated Window via this link.

http://bradhedlund.com/2008/12/19/how-to-calculate-tcp-throughput-for-long-d
istance-links/

It's amazing I get a good 30MB from a 3GB ISO off of a Server08 box. From
a Server 03, I'm lucky to get 85bytes on a 22MB file.

SE and AM are getting some WAAS and ASR quotes together. *Puts on nut cup*

Thanks guys,
JB

On Thu, Aug 16, 2012 at 3:27 PM, Joseph L. Brunner
<joe_at_affirmedsystems.com>wrote:

> We tried that extensively in windows 2003 and other things - never worked
> or made a difference....
>
>
>
> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> Dan Shechter
> Sent: Thursday, August 16, 2012 4:12 PM
> To: JB Poplawski
> Cc: ccielab_at_groupstudy.com
> Subject: Re: TCP Window Optiimization with LFN.
>
> It depends on what you are looking for: High BW, Latency issues or both.
>
>
> For a large window size,
> http://en.wikipedia.org/wiki/TCP_window_scale_option should do it. As
> long as there are no CRC errors on the path, there is no much harm
enabling
> it by default.
>
> For latency issues of chatty protocols, we will all have to wait for the
> results of CERN experiments to see if we can send packets faster then the
> speed of light... ;) . For some applications, WAAS "reducing" the latency
> is much more important than BW.
>
>
> HTH,
> Dan #13685 (RS/Sec/SP)
> The CCIE troubleshooting blog: http://dans-net.com Bring order to your
> Private VLAN network: http://marathon-networks.com
>
>
>
>
>
> On Thu, Aug 16, 2012 at 9:07 PM, JB Poplawski <jb.poplawski_at_gmail.com
> >wrote:
>
> > Good afternoon,
> >
> > My token question out to the group as I await TAC.
> >
> > I have a network with Gb links between sites. Connected like such:
> > Site A < 7ms > Site B < 71ms > Site C <9ms> Site D
> >
> > End to end latency between Site A and Site D is 69ms. My numbers
> > above are the average given from CLI.
> >
> > I've been reading on LFNs (Long Fat Networks) and basically I need to
> > optimize the TCP Window size (calculated to 8625KB).
> >
> > My question, where do I implement it?
> > Site A and Site D? Or Site B and Site C?
> >
> > If I implement on Site B and Site C, how does that impact Site C to
> > Site D, etc?
> >
> > Any ideas?
> >
> > We previously had MPLS connection with WAAS which optimized traffic.
> > Now since we're running Gb, we removed WAAS (our WAAS boxes were only
> > rated to 50Mbps).
> >
> > Any suggestions? Am I on the right path?
> >
> > Any help is greatly appreciated.
> > JB
> >
> >
> > Blogs and organic groups at http://www.ccie.net
> >
> > ______________________________________________________________________
> > _ Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html

Blogs and organic groups at http://www.ccie.net
Received on Thu Aug 16 2012 - 19:30:24 ART