Wireless AP's

Right, My school has recently had Cisco wireless AP's installed, to cover the entire school with wireless network access.

All but three of these access points work correctly, and unfortunately, one of those three is in my office.

With the Cisco AP's when nothing is connected to it, the light on the underside is Green, and when something IS connected to it, the light turns Blue.

The one in my room and and one of the Business Studies rooms stays Green ALL the time, and the signal is picked up from the nearest AP which is EXTREMELY low signal, and drops all the time.

When I went to the switch cabinet that the AP's are wired to, I unplugged my AP, and to my suprise, the AP in the Buisness Studies room went Blue, and the laptop in that room got 100% signal. As soon as I plugged mine back in, it doesnt work again.

The county council ICT centre havent told me much, but I am under the impression that each access point has its own IP address?

What tools are there available that I can install on a wireless enabled laptop to survey each of the AP's? Such as IP address, MAC, SNR, etc etc, cause I'd really like to see if there is something up with the AP's.

The county council ICT centre have just told me to leave it with them, but I'd rather sort the problem out now rather than wait 2 or 3 weeks for them to come out and go "We'll get back to you"

Any help is appreciated

Thanks

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What tools are there available that I can install on a wireless enabled laptop to survey each of the AP's? Such as IP address, MAC, SNR, etc etc, cause I'd really like to see if there is something up with the AP's.

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NetStumbler is got for signal quality etc.

http://www.netstumbler.com/

Ash.

Is your room and the business studies one close together?

If it is then they may be on the same channel and interfering with each other.

Ben

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Originally Posted by plexer

Is your room and the business studies one close together?

If it is then they may be on the same channel and interfering with each other.

Ben

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I'm with Ben on this one.. It sounds a lot like you have clashing channels.. either that or duplicate IP's being picked up by the units.

Might be worth using an IP scanner to find the unit IPs for the APs and see if they are all different to discount the latter as a possible cause.

where do i get a decent IP scanner that will give me some indication of whats an AP and whats not?

If they are getting ip's by dhcp have a look at the leases and that may point out which ones are allocated to ip's

If not have a look on the dhcp server to see if there any reservations or excluded ip addresses for static devices.

Ben

With wireless access points you have to be careful that the channels do not overlap. If you have all of the AP's on the same channel, and overlapping, you will find data transfer will fluctuate. You need to set up the access points on separate channels that do not overlap

The non overlapping channels for the UK are 1, 7, and 13.
Therefore, set each access point on a different channel (Choose 1, 7, and 13) If you need to use a channel again make sure it is not next to one of the same channel. In Beaumont School we have 20 Access Points (Running DD-WRT Custom Firmware) and they are spread out so that each device runs on either 1, 7 or 13 and no two channels are adjacent.

Also make sure you have no wireless equipment running that can affect the signal (We have wireless cameras.. darn things.. wish they would actually ask IT before buying them..) We make a habit of turning them off when we walk past!

As long as your network settings are correct (IP's, routing etc) then you shouldn't have any problems.

Also.. If they are access points then they are simply layer 2 devices and should not have an allocated IP address, just like a layer 2 switch wont have an IP. They may be stacked switches with a management console somewhere... with a core unit etc. That would be evil.

If they do have IP's they will be static... Use net stumbler to do a survey, or possibly look for reservations on your DHCP server

The uk non overlapping ones are 1,6 and 11.

All of my access point the simple buffalo ones and also the HP 420's all have ip addresses for management and setup of them.

Ben

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The non overlapping channels for the UK are 1, 7, and 13

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I was under the impression that they were 1, 6 and 11?

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Originally Posted by Samson

where do i get a decent IP scanner that will give me some indication of whats an AP and whats not?

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Do a search for "advanced IP scanner" on google and you'll find one that I use from time to time.

In terms of working out what is what it requires a certain amount of sleuthing but if nothing else you should be able to use your browser to try to access any web servers on AP's, switches, etc.. to narrow your search.

http://www.draytek.co.uk/support/kb_...nchannels.html

Overlapping channels are simply channels in a certain band. They are not a set frequency

You can use different combinations of channels which do not overlap, as explained by the previous link.

For myself, the surrounding area has lots of home wireless routers already on channel 6, hence i use 1, 7 and 13

Ok thats fair enough but you stated in your post that the uk non overlapping channels were 1, 7 and 13

Ben

This is Cisco kit ... it goes up to 13 (one higher isn't good enough ... they want to go *two* more!)

It is common to have 4 non overlapping channels with Cisco kit ... 1, 5, 9, 13.

This gives you the 3 dimensional cell topology (something that is not required in mobiles phone networks but damn handy for 802.11 based networks)

Yeah sorry Plexer! In all honesty I just always thought of them as default for everyone, i've only ever used those channels :-(