Author Topic: Wireless causes network dropouts....  (Read 1593 times)

Offline MyKroFt

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Wireless causes network dropouts....
« on: November 02, 2013, 03:37:06 PM »
Known issue.

The dropout with power management enabled is due to a quirky deficiency in handling multiple URBs queued for a single device in the USB driver. Power management will typically wake a thread every 200-500ms which will activate/suspend the radio frontend of the wifi adapter - this causes a flurry of control transactions which under certain circumstances cause USB packets for the device to get "stuck" in the queue.

This behaviour is reproducible most easily on a Pi with no periodic endpoint devices attached (Ralink adapters are favourites because they have only bulk endpoints). Model As exacerbate the problem because of no ethernet chip/hub. Probably the reason you're not seeing this until several hours have passed is because your 4-port hub has an enabled periodic endpoint, but hubs typically have a polling period of several dozen milliseconds. Having multiple endpoints/transactions queued at once causes the stuck packets to get properly processed.

So I guess I start looking for a powered hub....

Tony

Offline ron

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Re: Wireless causes network dropouts....
« Reply #1 on: November 02, 2013, 03:58:57 PM »
Tony,

I read what you wrote and have no idea what some of it means.  I understand the dropout issues with usb based wifi.  Will a powered hub most likely cure the issue?

Offline Steve Gase

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Re: Wireless causes network dropouts....
« Reply #2 on: November 02, 2013, 04:00:45 PM »
under what conditions did you see this problem?

I have a 4A 5V power supply that gives power to the FPD, the FPD gives power to the FPP using the USB connector.  From the FPP I have a un-powered hub with wireless, flash key, ...and sometimes I connect keyboard and mouse.  I don't connect the hub to power (yet) because I'm hoping the current flowing to the FPP will be sufficient.  Based on your research -- is my hope unfounded?
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Offline MyKroFt

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Re: Wireless causes network dropouts....
« Reply #3 on: November 02, 2013, 04:41:44 PM »
I have tried a TPLINK nano and now the edimax nano - both cause my network to drop out every 1 min and rekey with my wireless - which is like pulling the wireless adapter - most of the time the Pi dont like that.

I have tried the "wireless-power off " in the interfaces file like suggested - but still have the problem

Tony

Offline MyKroFt

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Re: Wireless causes network dropouts....
« Reply #4 on: November 02, 2013, 04:43:40 PM »
one thing I do need to figute out - I have 2 Pi, 1 orig model A, and the newer B - need to figure out which is which and use the B

Tony

Offline Materdaddy

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Re: Wireless causes network dropouts....
« Reply #5 on: November 02, 2013, 05:36:29 PM »
one thing I do need to figute out - I have 2 Pi, 1 orig model A, and the newer B - need to figure out which is which and use the B

Tony

cat /proc/cpuinfo

Then look at this table to see model/manufacturer:
http://www.raspberrypi.org/phpBB3/viewtopic.php?f=66&t=34611&p=293472&hilit=cpuinfo#p293472

 

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