Extricom Issue

Hi
Posted a thread about this in the classroom mangagment forum last week but I think it probably should be in here, sorry!
We have an Extricom ESXW 2400 switch, with 16 AP's around the school- primary school, old victorian building, thick walls. Around 70 laptops connecting via wireless plus 25 desktops wired in. Not often all at once though. We run a RM CC4 network, but around half the machines are standalones due to the insanely long log in times for the CC4 machines. Mix of XP and windows 7, OS doesn't make any difference to the problem.

The problem is often some (not all) laptops cannot get onto the network- they 'see' the wireless ESSID but cannot fully connect- no internet access at all, litte yellow ! on the wireless symbol. The clients can see the ESSID and connect but no internet access, which is mainy what they are used for. Same problem for standalones and CC4 machines.

The only solution that works is to pull the plug on the Extricom switch and then plug it back in. This usually works and laptops can access the internet once it's rebooted. On average this is once a day.

Network is set to WPA2 + AES, all clients are compatible with this. 2 radios per AP, broadcasting on 1 and 6, 1st radio is g, second is b/g.
I've read that Extricom needs to be on unicast rather than multicast- I've no idea how to configure this on Server 2008 R2 though- or indeed if this is the problem anyway!
Any ideas please?

Yes Extricom needs DHCP responses to be unicast rather than multicast because of the way the channal blanket works. Basically because of the time slicing round robin, if a client asks DHCP for an IP, when it responds it might be the tern of a AP at the other end of the building. So the client might not get a IP. if it dose that's just luck. See this link it should help you configure your DHCP server.

http://www.askdavetaylor.com/dhcp_unicast_broadcast_flag.html

Excellent! Thanks so much. Reconfigured DHCP server as per the article, all seems OK this morning!
One question- do I need to do anything with the clients or will they automatically request unicast?
Thanks