Network engineers? Wireless question?

[rob wild]

Hello just a quick question ;)

If you were installing a wireless network in a traditional building three floors. Now their will be anywhere from 20 upto 200 wireless laptops using the network at anyone time. The network needs to be fast i.e 108bps. My question is really how many access points do you think per floor? as im worried about the bandwidth and their is no clarification on the cisco website as to how many users one access point will support for example 25 users all accessing the network at 108.

Any advice would be good :)

Thanks Rob

[JustGav]

You won't get full bandwidth.. especially not with 200 laptops on it, remember they share the frequency. There is some VERY fancy kit which can get round it, BUT it will cost you.. I can dig out the details if you are really want them.

[TyranoSupraRex]

Slightly off topic, but don't forget to set up the channels to maximise efficiency. You should use 1,6 and 11 to ensure efficiency. It's the only combination that allows 3 channels. See http://www.draytek.co.uk/support/kb_vigor_wlanchannels.html and http://technet2.microsoft.com/windowsserver/en/library/b064b275-604f-43e8-a699-cb8e4676874f1033.mspx?mfr=true

[MaveriK]

Have a look at Cisco's new mesh setup, could be what your after.

[JustGav]

Have a look at Cisco's new mesh setup, could be what your after.

Hehehe, exactly what I was thinking, but it isn't cheap...

[rob wild]

Thanks guys i will have a look :) How far will 30k get me? Really i suppose what sort of speed could i expect to get if lets say 20-25 laptops were in the same room connecting to the same access point?

[SteveR]

108Mbps (I assume you meant Mbps, not bps? :D) will require 802.11'Pre-N' kit, or some manufacturer-enhanced 'turbo' 802.11b/g stuff, which could be limiting as you'll only be able to use 1 brand of kit (access point AND client).

Don't forget that;
1) any stated speed is the channel's speed, not the throughput (real bandwidth)
2) it's a theoretical maximum, for real-workld figures, halve the number, and then start sharing that between the number of clients you expect to hang off each access point (and reduce it a lot further if you end up having interfering APs on co-existant channels...

Check this out for how to be a bit cunning and use several Wi-Fi frequencies in the same building instead of the traditional 3.
http://www.cisco.com/application/pdf/en/us/guest/products/ps430/c1244/cdccont_0900aecd8027a5f7.pdf

Cisco have loads of really useful info if you search hard enough

[Alex]

Do you really NEED 108Mbps?? Top speeds and burst rates are great, but if they are just file sharers and internet users its stability not speed that you need.

I say this as there's much more 802.11g kit out there...which could give you more capability for you budget.

[JustGav]

Do you really NEED 108Mbps?? Top speeds and burst rates are great, but if they are just file sharers and internet users its stability not speed that you need.

Good point... If you need large bandwidth you really should use a cable....

[Alex]

Looks like Cisco have released something called the Aironet 1250, an 802.11n Access point....at $1200 a pop a few of these could see you right...possibly (not sure how available they are). Do lots of homework, and generally you can't go wrong with Cisco.

[M5W TT]

Agree with the use of 11g for stability. We put in the new Cisco mesh at one of our sites that use up to 25 Handheld PDA's to take menu orders for anyone up to 300 people on a race night and that works perfectly. We have 4 access points in two large rooms and its spot on.

One of the other race course have a new 11n cisco access point and when more than 30 devices are connected the speed really drops off.

Saying that its still stable just slower.

[Wez]

What do you mean by traditional building over three floors, is this an open plan office or an apartment block?

When we roll out new wireless networks to cover large areas we do lots of work before hand like mapping the wireless areas that require covering, we can then position the APs in the most effective position.

Are you able to cable each AP or will some have to be wireless repeaters.

Your choice of antenna will also determine how many APs you will need to cover an area.