Re: Wierd metro WiFi problem

Mesh networks of the type you have built can (and will, at some point) 
have latency and throughput problems however your original post 
indicates that you disconnected the wireless network and you still see 
the problem. To be sure that there are no port mismatch issues you may 
need to experiment a bit. Try setting the router Ethernet port(s) to 
"auto-speed" and "auto-duplex".

jack


Tyler van Houwelingen wrote:

> Agreed, unfortunately this does not appear to be the case.  We can use 
> the same interfaces and make the download speed change simply by 
> increasing the latency between.  We look at the switches, routers, etc 
> and there are no errors on the ports.
>
> a hypothesis of the problem is that maybe with an upload, the latency 
> and wireless hops are at the beginning of the link, causing any 
> retransmissions to be immediate.  with a download, the latency and 
> hops are at the end, potentially causing retransmissions.  We dont 
> however, detect any retransmissions.
>
> ty
>
>
>
> ----- Original Message ----- From: "Jack Unger" <[email protected]>
> To: "SeattleWireless Talk List" <[email protected]>
> Sent: Thursday, January 26, 2006 12:50 PM
> Subject: Re: Wierd metro WiFi problem
>
>
>> Could be a router Ethernet port speed-mismatch issue.
>>                                                        jack
>>
>> 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 <http://www.azulstar.com>
>>>
>>>
>>> ------------------------------------------------------------------------ 
>>>
>>
>>
>> -- 
>> Jack Unger - President, Ask-Wi.Com, Inc.
>> Serving the License-Free Wireless Industry Since 1993
>> Author of the WISP Handbook - "Deploying License-Free Wireless WANs"
>> True Vendor-Neutral WISP Consulting-Training-Troubleshooting
>> [email protected]  (818) 227-4220  http://www.ask-wi.com
>>
>>
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>
>
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>

-- 
Jack Unger - President, Ask-Wi.Com, Inc.
Serving the License-Free Wireless Industry Since 1993
Author of the WISP Handbook - "Deploying License-Free Wireless WANs"
True Vendor-Neutral WISP Consulting-Training-Troubleshooting
[email protected]  (818) 227-4220  http://www.ask-wi.com



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