ex-webby

Hi All

Any experts in this?

Have about 20 clients...

Clients all request connect at same time. Once connected, the client requests a full dataset from server of about 450K. Server sends out to clients as requested (in packets of around 30 bytes - variable), then incrimentally updates them as needed with small the 30 byte packets (probably 2 or 3 a minute).

When connection is dropped, client requests connection again and process for that individual client is restarted, all data, etc again.

This works perfectly over normal LAN and worked fine on wireless LAN one day, then really badly on another day (different location), clientss dropping constantly and eventually flooding the network with data that was never getting to the clients, clients reconnecting constantly, etc, etc, etc.

Any ideas? Is this a network issue, or is TCP over wirelesss inherantly dodgy?

Any advice would be appreciated.

All the best

Simon

IanW

Si,

Check the signal levels that the client is seeing on the wireless lan, every wireless card that I have seen has had a piece of software that will show the connection speed. Sounds to me like the signal is either very weak, or there is something causing some interference

At my old company we used to run a Wireless LAN, and had no issues with TCP not functioning correctly, and one of teh pieces of client software that we used to run was constantly talking to a couple of SQL servers etc...

Ian

Puff The Magic Wagon!

iTrader: (2)

Been doing this (tcp socket conns) over GPRS with not a prob. Definately sounds like interference/signal strength. GPRS/tcp has the potential for higher degree of failure due to vagaries of mast location/terrain and what I'm doing, which is constantly moving mobile units reporting to & receiving info from a remote server. Therefore its safe to assume that tcp sockets will work fine as GPRS is just a different type of wireless lan - with an increased number of hops between unit & server.

ex-webby

OK

As the LAN is moved all the time (around the world) and set up in new locations I think I'm just going to have to put some handling in to allow for crap connections. Maybe even stop servicing a client if it has a really bad connection.

Thanks for the info chaps

Simon

ChrisB

Our testing in a school showed that simply using a microwave oven next to a 802.11b link will drop the signal strength.

It's not near any catering facilities?

RoadrunnerV2

Wireless uses the same collision detection system as Ethernet so it comes down to signal how good is your signal quality.

Rule of thumb -

Any thing that runs on 2.4GHz can be potentially degrade your wireless signal.

Each environment is different. Atmospheric and structurally. For small wireless networks the best way to eliminate blackspots is to use wireless repeaters. Wireless repeaters increase your signal in particular areas.

Wireless 802.11b has 3 non-overlapping channels - 1, 6 and 11.
Wireless is like tuning a radio If you suffer bad interference try changing the channel to another non-overlapping one. If it improves then try fine-tuning channels around the non-overlapping one to find the best one

IWatkins

Simon,

In the environment you are working in also remember that there will be a lot of television people produced interference. E.g. those short range transmitters that camera crews use IIRC are also in the microwave band and will be much higher power than a wireless LAN.

Also note that firing up the microwave oven to warm your doughnuts will also have a detrimental effect

Cheers

Ian

ChrisB

I doubt they're left long enough for them to go cold Ian