Hi Hypernova

Wifi is just like any other Ethernet device before the arrival of Switches

Think of your room as one big hub

They basically listen to see if anyone else is transmitting and if not they will start sending their packet. If another wifi device is transmitting they back off for an increasing amount of time (if they clash again the back off timer is increased and so on) until they muscle their way into a free slot

See http://en.wikipedia.org/wiki/Carrier_sense_mu..._with_collision_avoidance

This is a variation on wired ethernet which uses http://en.wikipedia.org/wiki/Carrier_sense_mu..._with_collision_detection

It could be causing problems but no so you would notice. I'm living in a flat with 10 other flats you should see the number of wifi networks in this building!

The most likely culprit is going to be DHCP

http://en.wikipedia.org/wiki/Dhcp

Do you know if the so called DHCP Scope is set wide enough to allocate an address to all the device wired or wirelessly connected to the router?


Another possibility is drivers and hardware compatability. Some router wifi chipsets prefer similar hardware in the wifi card/dongle attached to your PC otherwise they won't play nicely

If the signals were analogue then the preamp on the receiving radio might saturate with the transmitters so near but this is the digital world and saturation is just a 1. Plus Wifi manages the transmit power levels to keep them to the bare minimum required to maintain the data link. So this is unlikely to be the cause.

Not to worry anyone but they do operate in the same frequency band as your Microwave Oven 2.45Ghz - just on a lot lot lot lot lot lower power level in the same ISM band http://en.wikipedia.org/wiki/ISM_band - as does that bluetooth headset and dongle


Another posibility are the flavours of 802.11

It started off with 802.11b which transmitted at 11, 5.5 and 2Mbits
Then they changed the method and added 802.11g at 54Mbits
Then we have 802.11N on 150Mbits and N+ with the claimed 300Mbits

There's so much locking on and clock extraction gubbins going on each packet that these figures are just a technical myth that help sell product but each version is faster, just not as fast as claimed on the box.

The thing with 802.11 (apart from the a version which had to be different and transmit in the 5Ghz band) is that they are all backwards compatible so a N+ dongle should interwork sucessfully with even a "only b" router by changing down the gears and transmission method back down to even 2meg

but....

back in the real world it's probably best to choose the lowest common denominator between all of your wifi kit and set them all the same to get your wifi to play ball nicely

So if you don't have any old b gear a couple of N+'s and the rest 54Mbit g then set all the drivers and your router to g then none of the kit has to think and negotiate a supported speed before they send the packets back to the WCG. They just go hey I'm g I'll try this 54M speed first - job done


Then there's Windows 7 which from bitter experience is a law unto it's own when it comes to wifi - I ended up using Homeplug instead - looking forward to service pack 1

My netbook will only wifi to my router if I allocate it a fixed IP address, outside the DHCP scope in the same subnet - that's the hardware compatibility again

The best way and probably the cheapest option, with Ethernet now built into most motherboards, is probably to invest in a cheap as chips switch and a bunch of cat5 RJ-45 leads and then plug just one cable over into your router. If you don't want to drill through a wall get a homeplug set to bridge the gap

The stress levels are much lower that way

I know


Dave

CEP2 is an upload bandwidth hog. The only way I was able to get things to upload consistently was to limit the upload bandwidth to 80% of my total upload capability. With multiple machines running you may need to additionally limit the upload from each machine so 80% is not exceeded if they were all uploading simultaneously.
Davids' suggestion to hard wire everything is also a good idea IMHO.

I did the change. All units save three are now connected by cable. All seems stable and more reliable now.
I had also a discussion with my internet connection provider. And he had excellent news for me. By mid december they will offer a 100 Mbyte/sec connection for a slight additional cost over my existing contract. At the moment I had the maximum that they could offer me as a private user that was 25 Mbyte/sec connection with 2 Mbyte/sec upload. This will change to 100 Mbyte/sec download and 7 Mbyte/sec upload. That is excellent for projects like CEP2 that are upload intensive.

Sek I am dreaming of DDDT2 WU's coming by torrents.
I have already suffered terribly from thirst since many months, in this desertic environment, expecting rain hallelujah. Fortunately a few drops here and there come just to have me survive with hope for a better future.

Nevertheless I am alive and my farm gears up for big uploads, so it is time to change the status of "persona non grata" that my farm had from this project.