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Dropped data packets as Linksys Wireless -G Range Extender (Model WRE54G) is moved closer to router

Posted on 2008-06-21
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Last Modified: 2011-10-19
Hi Everyone;

        I am faced with a very unusual situation.  Basically, I have a wireless pc on the other side of my house which depends upon a Linksys Wireless-G Range Expander to get the signal it needs to communicate with the router.  Lately, we have noticed something very unusual which seems to be a function of the location of the range expander itself.  First, we were experiencing frequent lost data packets from this wireless pc which depends upon the range expander.  Specifically, while the signal strength was "excellent", there was limited or no connectivity with the router.  When I ran a ping test to the router, I was getting anything from 50% to 75% lost data packets.  

         Further investigation into this situation revealed yet another unusual problem.  If the wireless range expander was placed in the middle of the house, thus, being closer to the router, there was not any dropped data packets to the router and internet.  However, the signal strength this time was "very low".  Logically, should there be more dropped data packets in incidences were there is low or very low signal strength?  And, in sharp contrast to this, should there be more successful transmissions of data packets when there is excellent signal strength?

         In closing, I look forward to reviewing everyone's feedback to this rather puzzling and paradoxical question.  

        Thank you

        George
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Question by:GMartin
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by:blimster
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ID: 21839326
The signal strength that you get is from your pc to the range expander not the router.
If you ping your expander then you should get good results.

The problem here looks to be the link strength/quality between the range extender and the router.

It is probably the delay of jumping through the extender or the timeout settings on the extender or router itself.

Try do a ping from the PC to the extender and see what the response is.
Then try a ping from the Extender to the router.

add the two highest response time together and abit of buffer on top and if it's higher then say 4000 ms then it would timeout from your PC to the router.

Check which one has the higher response. There's your problem.
Droup out and poor response can be caue by other electrical equipment near your wireless device or in between. If you're going through a wall or wall try keep the number of walls your going through as low as possible from one wireless device to another or position the devices to have direct line of sight if possible if it means having to do zig zags with the devices.
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by:Darr247
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> Specifically, while the signal strength was "excellent", there was limited or no connectivity with the router.

Are you going by what windows is telling you the signal strength is?
Because I find nowhere in the WRE54G interface to see an indication of the received or broadcast signal strength, let alone what the noise floor looks like.

The usual causes of lost/dropped packets are low signal-to-noise ratio (SNR), collisions and interference.

Assuming you don't have access to hardware with which to do a comprehensive spectrum analysis, you could look at it with some software tools like Kismet, Network Stumbler, Wireshark (ethereal) and AirSnare.
Network Stumbler (http://stumbler.net or http://netstumbler.com) will probably give the quickest picture of the SNR other transmitters nearby... it will take a spectrum analyzer to see other interference like microwave ovens, cordless phones, baby monitors et al. You can manually shut down those things you have control over, but if there are neighbors all around the only thing you'll be able to see for sure are other access points and wireless cards.

Anyway, even with a lower indicated speed because of the lower signal strength as measured at the wireless card, you can still end up with higher effective throughput if there are less resends required because of the higher SNR between the router and range extender.
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by:GMartin
ID: 21841697
Hi

       I am going by what the wireless zero configuration built within Windows is indicating.  We switched to this one because it seems to have more reliable performance with respect to stable connectivity than the WRE54G interface built within Linksys.

       George

       
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by:Darr247
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ID: 21841929
Well, have a look at what Network Stumbler says as far as noise, and how many other stations/clients there are nearby that might be using the same channel (or within 5 channels on either side if you're still using the default channel 6).
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by:GMartin
ID: 21842084
Hi

      Thank you so much for the followup.  Regarding Network Stumbler, how may I get started with this program?  I have never used it before, so, any beginning instructions will certainly be appreciated.  
While this is certainly a troubleshooting scenario here, I also want to gain some knowledge and experience from it as well.

       At the moment, we are using Channel 1.  We tried Channels 6 and 11, but, had larger numbers of dropped data packets which resulted in dropped connections between the wireless and router.

        Thanks again.

        George

       
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by:
Darr247 earned 450 total points
ID: 21842652
Use the download link from either of the 2 sites to obtain version 0.4.0, and install it.
Not all cards support it, and different chipsets provide different levels of data, but its use should be pretty straightforward.

When run it will disable the WZC service temporarily, then start monitoring through your wireless card. It does not disconnect you from the network. It always comes up running for me, but if it's stopped press the green 'play' button on its toolbar.

Let it run for a half hour or so, and with Channels slected on the left note how many SSIDs it has found and what channels they're using on the right. The longer it runs the more data it collects/compiles/graphs. If using a laptop walk around to different location with it and note any changes.

The netstumbler1.png grab below shows how many b/g APs it found in my girlfriend's neighborhood (sitting still... if I had walked around the block with my laptop I'm sure it would have found many more).

When you open the SSIDs on the left and click each MAC address it should show you a time-graph of the SNR.
See  netstumber2 and 3.png for examples of what graphs showing strong and weak signals, respectively.

It has pretty good help screens, too.
NetStumbler1.png
NetStumbler2.png
NetStumbler3.png
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by:GMartin
ID: 21842846
Hi There;

        Thank you so much for the prompt feedback.  I noticed within Network Stumbler ther are 2 AP (Access Points) with the same SSID or wireless name of MSHOME.  Of course, we have one router with a wireless name or SSID of MSHOME which is true.  However, should there still only be one AP or access point because we only have one router?  Perhaps the program is also picking up the Linksys Range Expander.  If the range expander is being utilized as an access point as well, then, could it possibly explain why there are two AP's?

         Any information regarding these followup questions will certainly be appreciated.

         Thank you

         George
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by:Darr247
Darr247 earned 450 total points
ID: 21843528
> However, should there still only be one AP or access point because we only have one router?

ALL access points or routers or range expanders or bridges or repeaters within range should appear eventually, even multiple instances of the same SSID. Sometimes it takes a while for them to show up, that's why you want to leave it running at least a half hour. You should be able to tell which is which by the MAC address printed on the barcode sticker on the bottom... the Linksys MAC address should begin with 001310xxxxxx (the first 6 chars identify the manufacturer; the last 6 chars are unique to the device).

>  Perhaps the program is also picking up the Linksys Range Expander.

Yes. And it should also give you a good picture of the SNR between the client and the range extender, and between the client and the router too.  How do their signal graphs compare to those I posted earlier?
If the graph for the router is solid green with a SNR above 50 you might not really need the range extender.
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by:GMartin
ID: 21843561
Hi There;

        Thank you so much for the followup.  I installed Network Stumbler on another one of my wireless pc's earlier tonight, but, ran into a warning message.  Basically, the program indicated that this wireless will only list its own SSID and noone else's SSID because of the current configuration of the wireless (e.g. which is a Microsoft Wireless USB Network Adapter, Model MN-510).  Additionally, the other pc which revealed a nearby wireless earlier is not listing any other than its own SSID.  However, when I go into View Available Wireless Networks within Windows, I see several.  I am not sure what to make of that situation.

        Any thoughts regarding these followup issues will be appreciated.

        Thank you

        George
 
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Author Comment

by:GMartin
ID: 21843611
Hi

       If it would not be too much trouble, could you possibly look at an open thread I have going?  The link is http://www.experts-exchange.com/Hardware/Peripherals/Mice_Keyboards/Q_23506362.html#a21843029

       Thank you

       George

             
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by:GMartin
ID: 21892516
Hi Everyone;

        Thanks so much for the well thought out responses to this thread.  I certainly learned much from this link as a result of the well organized suggestions and guidance given.  Especially helpful was the information and link to Netstumbler given by Darr247.  Over the last few days, I was able to use this handy tool to monitor the Signal to Noise Ratio between the wireless client and the router along with the range expander.  Through this tool, I was able to isolate the culprit for the unstable connections.  Basically, whenever a neighboring wireless signed on, I noticed a significant drop in signal strength along with an increase in dropped data packets.   Upon these observations, I drew the conclusion there was interference caused by the nearby wireless.  Interesting, this interfering wireless did not occupy the same Channel.  For instance, we were on Channel 1 wereas the interfering wireless was on Channel 11.   Following these observations, we closed Netstumbler and launced it again.  We did notice the program seems to temporarily disable Wireless Zero Configuration.  But, Wireless Zero Configuration does come back on after the program is closed.  Interesting, when the Wireless Zero Configuration was refreshed by disabling it and re-enabling it, the problem with the dropped data packets seems to cleared up.  About that time, the nearby wireless signed off as well.  

         While there are still occasional disconnections between the wireless and the router,  the frequency of the problem is not near as bad.  And, through continued use of Netstumbler,  we will be able to make adjustments accordingly.  After all, one day the wireless may detect one nearby wireless and on the next day may detect as many as six.  With that in mind, if nearby wireless networks are interfering, the changes made within the router with respect to channels might be an ongoing process.  Incidentally,  just as an extra note, if a channel is changed, it must be changed within the range extender first and then to the router.  

            Well, thanks again everyone for the feedback.  I certainly gained a great deal of knowledge of the behind-the-scenes mechanisms which can be responsible for dropped data packets.

            Many thanks again for a job so well done.

           George
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