Wireless site survey

[KWestos]

Hi

 

I had a site survey yesterday to cover the whole school for wireless access. Please could you kind people clarify a few queries I have which resulted from this visit:

 

* I was told I would need access points in EVERY room - is this correct? The system I beleive they are pushing is the new netgear wireless (quite reasonably priced - I think about £1000 for the switch and £100 for the AP's. Each one of these has to be physically located into the wired network true? - I dont have POE capability (I was origionally told by the salesman these would just wirelessly pick up the central switch with no need to be connected to cabling.

 

* I need a managed setup for around £3000 - is this the best setup for the money?

 

* Also, I have heard of ZyXel - is this a good solution?

 

* In the mean time I need a very quick solution to a small laptop trolley. Is the HP Procurve 420 with access points any good?

 

Many thanks

[mrforgetful]

Definately a managed solution.

 

Do you know what your core switch is? Only reason I ask is with our HP Procurve 5308xl it is possible to buy an addin card to manage HP wireless APs.

 

As for each one being wired in I guess it depends, sounds the fastest most reliable method with the only other option really being repeaters.

[plexer]

Who did the survey and what did they use to do it?

 

Where they a company that specialises in wireless or just a network company that offers wireless.

 

If you have a scaled site plan companies like react technologies can use software from aruba to do a wireless power plan.

 

This would be backed up by a site survey to make sure the plan is accurate.

 

AP's in every room sounds a bit strange unless they are configured for no leakage whatsoever so they don't interfere with each other.

 

My whole wireless system is based around HP 420 access points with Airwave amp as the controller.

 

How many access points did the survey say you needed?

 

I've never seen a wireless network where the access points didn't need to be plugged into the network.

 

Ben

[KWestos]

Hi

 

Mr Forgetful - My core switch is a HP 5304XL

Plexer - the company I will not say, but they are a reseller who "do" wireless installations. I must say I was incredibly annoyed at the survey as all he did was walk round the building noting things down as to the estimate of wall thickness and room sizes. No measurements were made or a survey of any kind - just a visual!

Could you please expand on you're quote - "I've never seen a wireless network where the access points didn't need to be plugged into the network." I thought some AP's could connect wirelessly or piggybag off others to the main Wireless switch.

 

Many thanks

[HodgeHi]

Did you visit the stand at the Bett show?

 

If you didn't then they were promoting a managed system from the switch (£1100) to the APs (£100-£110 each). The guy gave me a talk and a demo of the system which i personally thought was quite good.

 

The APs are connect to the switch which centrally manages the APs and also powers them. The good thing about these AP's was that they were "clever" in that they detected load and then moved users to a second AP if it was too busy.

 

It also powered up and down signal strength if one AP was detected as offline, therefore covering the area that the offline access point would cover.

 

It also had a built-in "automatic site planner". You imported a floor plan into the switch with dimensions and then the switch apparently pointed out the optimal places for your access points to provide the best cover. The AP also provide seamless roaming. For the cash it didn't sound too bad although it is all just theory unless someone has used them already and can vouch for this system.

 

The system is of a collaboration between Netgear and Aruba.

[paul]

A proper survey company would use a piece of software to predict RF penetration dependent on wall construction, number of walls/floors. this would then be followed by a proper onsite survey testing the software's predicted results. May I suggest you opt for a company who’s background is RF as apposed to hardware/software. One AP per room seems excessive I’m also guessing they have not planned for RF bleed over from the adjacent AP’s which may also be on same frequency.

[plexer]

Well as I said all the wireless installations I've ever seen have a network point for the access point to plug into.

 

If this controller is powering them it is using power over ethernet and therefore requires a network socket at each access point location.

 

Ben

[plexer]

A quick google reveals all about the aruba netgear tie up I think.

 

Aruba released it access point code so that other manafacturers could make access points that can be configured with the aruba controller rather than restricting you to buying aruba access points.

 

Netgear is the first company to sign up to this and get its products certified.

 

The other thing also is that if all of your access points can not be reached by copper cabling from the location of the aruba controller you will need multiple controllers I believe.

 

Ben

[Adam]

I agree. We're doing our own site survey using wifi laptops and access points, and there's definately not a need to have one in every room. If you do have one in every room I imagine cross-talk is going to be a problem, as you've really only got 3 or 4 distinct channels that don't interfere with each other. So...... If you've got a square ish block of 4 average sized room the frequency overlap of the channels means you're probably going to have problems. Does that make sense?

[mrforgetful]

There's a Wireless Controller addin card for your Core Switch here but be warned, it is not cheap!

[joe90bass]

I agree. We're doing our own site survey using wifi laptops and access points, and there's definately not a need to have one in every room. If you do have one in every room I imagine cross-talk is going to be a problem, as you've really only got 3 or 4 distinct channels that don't interfere with each other. So...... If you've got a square ish block of 4 average sized room the frequency overlap of the channels means you're probably going to have problems. Does that make sense?

 

That's my understanding as well. We don't have APs in every room, and when the survey was done the guys used an AP and a laptop to test the strength in surrounding rooms.

[dhicks]

I thought some AP's could connect wirelessly or piggybag off others to the main Wireless switch.

 

Yes, a "repeater" can extend a wireless network without itself needing to be plugged into a wired network socket. This isn't a good solution for a school-wide system, though, as it uses up available bandwidth. Only good if you really can't get a network point to where you want it.

 

--

David Hicks

[petectid]

A proper survey company would use a piece of software to predict RF penetration dependent on wall construction, number of walls/floors. this would then be followed by a proper onsite survey testing the software's predicted results. May I suggest you opt for a company who’s background is RF.

 

I'm with Paul on this sounds to me like they did not carry out a wireless survey at all. Making notes of wall thickness seams senseless as the most important part of survey is whether the wireless signal can penetrate obstacles. Then to come back and say you need an AP in every room, what was the point of turning up for a survey, in most installations this would work. A wireless survey should involve wireless signals using different antenna to check their suitability in any one area of the site. Sounds to me like they want to sell you as much hardware as possible, and you probably do not need it.

[projector1]

get another angle on it, dlink do a free wireless survey and see what they recommend.

I think it's andrew taylor who looks after the education market.

We got them to do the survey and then bought 2100AP's and positioned then where instructed and on the channels recommended.

[chesswill]

Just out of interest how much did you pay for the survey, you mentioned that the company in question mentioned thet you should have an AP in each room, this will all depend on exactly what you are trying to acheive.

 

what exactly did the survey entail, and how long were they there for, i work for HS Dataline, and we offer the complete solutions.

 

We were exhibiting at the bettshow last week, on stand T27 long with a company called worldwide solutions, offering a VOIP communication devise that works entirely over the wireless network called Vocera.

 

If you are interested have a look at our website, and have a look at our portfolio,

http://www.hsdataline.co.uk or

http://www.educationalnetworks.co.uk

[KWestos]

Many thanks for the responses. I have just spoken to Misco and am waiting on a callback to arrange a site survey by Zyxel - is this ok? Are ther any other solutions just as good as zyxel for the price?

[chesswill]

Try looking at Trapeze wireless, this one produce that we offer other than cisco and HP

[broc]

We paid for a wireless survey to be done; the engineer came with a wireless enabled laptop & PDA and other bits of kit to generate and measure signal strength around the building. He spent a day onsite. We were asked to provide a site layout diagram prior to the visit.

A few days later we got a professionally produced report which provided precise details of how many APs we would need, their placement and orientation. It came out at a lot fewer APs than I was expecting. We went with the solution the supplier proposed, based upon 3Com WX2200 wireless LAN Controller and AP2750 MAPs. To save costs we did the installation work in-house. We used PoE to power the MAPs, in one area where we were short of space in the network cabinet we installed a PoE enabled switch, in another area we used PoE 'injectors' at £10 a port.

[ricki]

HI

 

I have worked with wifi before in several schools and one in particular so the following advice is from 3 years of experience of it.

 

Wifi is a pain in the bottom. When you go down this road make sure you have lots of technician time to fix the day to day problems.

 

When the people say dont have more than 10 machines to a wifi router they are not kidding. Staff will take no notice and will have 30 to 40 machines connected to a router and will complain it will not work.

 

Hair dryer, microwaves, cookers and loads of other electrical kit will interfere with your wifi and so you may find that at times you dont get a wifi network and staff kick off about it.

 

Ghosting on the network will kill wifi dead.

 

Sophos and wsus also take large amounts of band width at times and so will make a slow network even slower.

 

Wifi is a security nightmare. If you set up the security with wpa and a key it will work but is not that secure, but is you use encryption and security its a pain to set up and causes huge amounts of problems and slows the wifi down.

 

Many staff want folders synchronized and this take ages after a bit and uses large amount of band width.

 

You also have the problems of scripts and network policies not applying correctly to machines.

 

Over all wifi is a pain and only do this at your own peril.

 

Richard:eek:

[plexer]

While I agree that wifi can be a pain I don't agree with everything else you've said.

 

Security wise it is easy enough to use ias or a 3rd party radius solution, such a funk steel belted radial or elektron which is what I use.

 

The processing overhead for proper security over a psk shouldn't be any different it's still encrypting stuff in the same way it's just a dynamic key instead of a static one.

 

With a proper site survey and a managed solution problems are pin pointable.

 

I ghost on our network and have no problem with it killing the wifi same for anything else such as av updates.

 

Ben

[dbrown]

I'm no expert on this, but we've had a wireless system installed for 15 months and I have a few views now.

We had the wireles installed because we got a load of laptops and wanted them to connect to the network. SCS did the survey and installation. We have 8 Cisco Aironet APs using POE. New wires were installed for each and led to the nearest existing D-Link switch. POE power packs were installed by the switch. I have never done any maintenance or changes.

Thoughts:

1- I need wireless for the portables, but I'd always want to use wires wherever possible. The laptops give far more trouble than the hard-wired stations.

2- I don't know what people are talking about with "wireless controllers". We just have the APs. If I want to use laptops in an area of the school not covered, I just unplug one of the little used ones (eg Dining hall) and plug it into any wired NW socket where I need it (move the POE power pack as well.)

3- SCS said each AP would comfortably support 20 laptops. I find even 15 gives very slow logons (10min+) or even refusal to logon, but once logged on they seem ok. (btw SCS have been no help at all in dealing with this issue, so I couldn't recommend them as people to deal with.)

4- We use 11g 54Mb and the cabling is 100Mb: the first few stations to log on claim to get 54Mb access, but further stations get rapidly decreasing bandwidth. By the time you get to 10 they are down to 1Mb or no access at all (which I think accounts for 3.) Once logged on and running, they again claim to have full 54Mb available. [This seems to be another example of the "business" model assumption of diversity loading not applying to schools, where we have very low average but very high peak loading.]

5- POE seems a good idea: having power sockets installed near APs would cost a lot more. I have one switch with 6 POE power packs taking up space, needing mains sockets and adding many yards (metres) of cables to the cabinet, so I think I would go for a new POE switch next time. It looks like it adds about £100 to the cost of the switch, which is the cost of about 4 of our power packs. Having one moveable AP with its own power pack has been very useful for temporary lashups.

6- Fault-finding: at least half the calls I get with laptop problems are cured by switching the wireless back on! (Toshibas with very badly placed switch)

[Sirbendy]

We're wanting to trial wifi in our existing building for trolleys of 30 laptops, as "proof of concept" for engineering a similar system into our new academy building in 2009ish.

 

At the moment we have a DLINK 2100AP in my office, this covers a fair radius of the middle floor considering it's sat inside the cab. We have a big DLink AP in our sports centre for outside e-portal access via PDA, and we seem to have sprouted another LEA one I can get on my IPaq in our library.

 

As a proof of concept, would using APs like these in various areas around the building, along with our laptops/IPaqs to test range and strength be a workable solution anyone would practise, as opposed to getting someone in?

 

We HAVE used them for laptop access before - it seemed passable. Only lightly loaded though..1 or 2 machines at once. They all link back into Cisco 3550 (IIRC) switches. I have seen schools local to us that have had LEA installed Wifi, and I've heard a lot of horror stories..but we could do with at least 1 extra "ad hoc" IT facility, and if it was portable so much the better..

[contink]

If it's any consolation I went into a school I'm soon to be handling a major upgrade for (including 60+ laptops although I'm trying to reduce that) and there was some bod in from a networking firm doing what I "think" you could call a wireless survey.

 

Now bearing in mind this is a school with 5 wireless AP's rated at 54g each dotted widely around the school on an unmanaged system with WEP (yes I know!) installed.

 

I quote more or less verbatim some of his more choice bits of commentary

 

Well I can't seem to get on the network, can't work out why... perhaps they have some authentication procedure on here

You think?!

 

I've been round the school and gotten a good idea of what you can do... I get 54mb on my laptop no problem so to my thinking you could get a couple of hundred laptops on each access point, no problem

I think I just about managed to stop my jaw dropping open or any falling to the floor holding my sides at this point.

 

Luckily the ICT co-ordinator listened to my basic "54mb shared between all computers connected to it" explanation. His look of WTF?! was somewhat priceless when we reviewed the earlier quote... *sigh*

[mrsrgj]

I don't know if it is of any help but please ensure you go for 4th Generation Wireless - you will need PoE and probably a controller unit which will work in the same way as Air Traffic Control is set up.

I can recommend a good Company if you wish to email me and also give the names of some schools using the equipment without a hitch - logging on 65 notebooks at once in under 20 seconds - pretty good going I think - also gives roaming etc.

The HP 420wl is certainly a quick fix from a trolley but don't expect it to fly with more than 5 notebooks.

 

Rai

[contink]

I don't know if it is of any help but please ensure you go for 4th Generation Wireless - you will need PoE and probably a controller unit which will work in the same way as Air Traffic Control is set up.

What would "4th generation wireless" be? Are you referring to the new 'n' standard or something else ?