Re: Wierd metro WiFi problem

One more thing I forgot to add this might also be and issue of MTU. While
doing tests with lperf use multiple MTU settings.



On 1/27/06, Faisal Rahman <[email protected]> wrote:
>
> Hi Tyler,
>
> Here is a link for UDP Bandwidth Test Utility
>
> http://dast.nlanr.net/Projects/Iperf/
>
> The error count seems quite small to have such drastic effect. Btw, what
> is the time frame for the error count?
>
> Also try changing your patch/cross cables.
>
> Faisal
>
>
>  On 1/27/06, Tyler van Houwelingen <[email protected]> wrote:
> >
> > My netstat -s is below.  This is across 2 5GHz wireless hops (1 mile
> > each),
> > one of which has about 2Mbps of constant metro WiFi traffic.   I have
> > about
> > 10ms of latency back to the Main Internet router from my test.  Links
> > quality is exceptional on both.
> >
> > Recieved packets discarded:  234
> > Recieved packets delivered:   4180
> > TCP Segments recieved:  2583
> > TCP Segments Sent:  2271
> > TCP Segments retransmitted:  15
> >
> > Can anyone recomend a nice tool or utility to watch the receive errors?
> > They seem to be getting out of order or some other issue.
> >
> > Tyler
> >
> >
> > ----- Original Message -----
> > From: "Alberto Escudero-Pascual" <[email protected]>
> > To: "Tyler van Houwelingen" <[email protected] >
> > Cc: "Claude" <[email protected]>; "Alberto Escudero-Pascual"
> > <[email protected]>; "SeattleWireless Talk List" < [email protected]
> > >;
> > "Juan Rivero" <[email protected]>; "Dave Tapscott" <[email protected]
> > >;
> > "Paul Stark" <[email protected]>; "Greg Vert"
> > <[email protected] >; "Marc Van Houwelingen" <
> > [email protected]>;
> > "Jose Manuel Gonzalez Saez" <[email protected] >;
> > <[email protected]>
> > Sent: Thursday, January 26, 2006 1:09 PM
> > Subject: Re: Wierd metro WiFi problem
> >
> >
> > > Hi Tyler,
> > >
> > > What do you mean by "you add a little latency" to the download. Do you
> >
> > > artificially add delay into one of the hops? How is your testing PC
> > > connected to the backbone?
> > >
> > > The best way to ensure that it is not a TCP implementation related
> > > behavior is to run some kind of UDP stateless tests.
> > >
> > > Check the following link (Section 2.1), might give you some hints!
> > >
> > > http://www.29west.com/docs/THPM/tcp-latency.html
> > >
> > > Alberto
> > >
> > >
> > >
> > > On Thu, 2006-01-26 at 12:05 -0700, Tyler van Houwelingen wrote:
> > >> I am contacting the best wireless minds I know to help with a bizarre
> > >> issue that has us stumped.
> > >>
> > >> Situation:
> > >> - We have 4 bonded T1 lines currently for our backbone, running a
> > >> large (400 AP) metro WiFi network.
> > >> - When connecting directly into the backbone router, we get 6M down,
> > >> 6M up as expected.
> > >> - However, when we begin to add a little latency between a testing PC
> > >> and the backbone connection, the upload speed stays the same, but the
> > >> download gets hammered.  With 10ms of average latency from the metro
> > >> WiFi network side, the speed drops to 2M down and 5M up.  At 40ms, it
> > >> is around 800k/5M.
> > >> - The wireless communications are more than fine as we get 8M/8M back
> > >> to our headquarters from anywhere in the metro WiFi network.  The
> > >> problems only come from testing into the Internet.  We get the same
> > >> goofy results when we disconnect the city network completely and just
> > >> add latency in the lab.
> > >> - We have run all the DrTCP (MTU, RWIN) like tricks which provides
> > >> some improvement, but not much.
> > >>
> > >> Why would this additional latency kill the downloads so much?  I
> > >> suspect the problem is with our backbone provider (Expedius) or some
> > >> limitation of metro WiFi that worries me.  In our other metro WiFi
> > >> network, we do not see this, but they all use a different backbone
> > >> provider (AT&T).
> > >>
> > >> Any suggestions to debug/fix this would be very much appreciated.
> > >>
> > >> tyler
> > >>
> > >>
> > >>
> > >> Tyler van Houwelingen
> > >> Founder and CEO
> > >> Azulstar Networks, Inc.
> > >> 1051 Jackson, Grand Haven, MI 49417
> > >> 1117 Rio Rancho Blvd 13, Rio Rancho, NM 87124
> > >> 1-877-AZULSTAR
> > >> www.azulstar.com
> > >
> > >
> >
> >
> > _______________________________________________
> > Talk mailing list
> > [email protected]
> > http://seattlewireless.net/mailman/listinfo/talk
> >
>
>

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