Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium

x
?
Solved

Wireless in a multi-story building.

Posted on 2005-04-18
34
Medium Priority
?
1,118 Views
Last Modified: 2012-05-05
Hi there,

I'm left in charge of setting up a wireless network in our office. We've an open office environment with cubicles and some rooms on the corners and sides. The office consists of 4 floors. It looks like 2 access points on every floor would be enough to get everyone connected,, but the catch is that I want people to use the same AP name for any given AP on any given floor. I don't want people needing to select new APs as they are moving around with their laptops from floor to floor or room to room. Is there a solution that I can use which would work with a single AP name by combining the signals of all the APs in the network?

All users will be using the wireless network and we're planning to get rid of the ethernet cabling for good. There are about 200 users in total who will be connected to the network all the time. I'd also prefer a G network if possible.

I'll be waiting for your suggestions.
0
Comment
Question by:egeiyioglu
  • 8
  • 7
  • 7
  • +4
34 Comments
 
LVL 6

Expert Comment

by:gjohnson99
ID: 13811779
All your AP's will have a single SSID - like the_office  the station move to the AP with the best signal. With that many users you will want to use 801.11A.  
0
 
LVL 1

Expert Comment

by:drnacboozway
ID: 13811867
Make sure you use different channels so they do not interfer with each other, and check this website out:

http://www.netmotionwireless.com/default_swf.asp

this company has software so when your card drops the signal no work gets lost. This way if it does happen that you lose a singal between AP's you can keep working as soon a the next AP pick up as if you never lost a signal.
0
 
LVL 7

Expert Comment

by:minmei
ID: 13812159
egeiyioglu,

Ignore this part of post if you have already made the decision to go wireless and will under no circumstances change your mind.

--------------------------

200 users over four stories with 8 total access points?

Your first problem will not be the SSID synchronization - that's pretty easy and only involves setting up each AP with the same SSID name. Your first problem will be bandwidth. Each access point acts as a shared hub. Not a switch, a hub. All clients attaches to it will _share_ the bandwidth. So even if you go 802.11a or 802.11g (54mbps), the throughput will be less (22mbps) an will be shared amongst 25 users each (200 users / 8 AP's). An average of 1-2 mbps for each user is not an upgrade from whatever you have now.

You will have drops between AP's as the clients reassociate. You have options (Symbol/Cisco/Nortel/Trapeze/Aruba) that do active AP handoffs so the client's don't have to reassociate and get new ip's. This really helps the handoff time from seconds to milliseconds.

You will have problems with too many clients per AP (it won't balance unless you get a higher-end AP solution)

What (or who) gave you the idea that wireless would be so much better? Did you have awful cabling and 10mbps hubs? Are your users being hung by the cabling from the ceiling?
100mbps switches are cheap and much more effective than the alternative.

Now don't get me wrong - wireless is great, for many applications. We put in a cancer center with 24 APs where they use laptops, wireless over IP phones and a Vocera application.
But this had wires for all stationary PC's for bandwidth.

-----------------------------

If you need to use wireless...

Do all G. Do more like 16 AP's. Pick a vendor that allows auto-load balancing like Airespace/Cisco or Trapeze. You will want no more than 12 clients per AP. Pick channels for each in a hexagon layout like the below...


Ch. 1       Ch. 11      Ch. 6
       
        Ch. 6       Ch. 1       Ch. 11

Ch. 1       Ch. 11      Ch. 6

If you have 4 floors, you could put the AP's on floor 1 near the ceiling and cover the first two floors, and use the floor 3 AP's for floors 3 and 4.

I hope this helps, and wireless is a great thing, but you may need wires for some users, especially ones who need more bandwidth.

0
Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 6

Expert Comment

by:gjohnson99
ID: 13812521
I you use 802.11a you can have up 13 none over lapping Channels and with turbo you a can get 40 plus Mega bits per AP. For my users I figure  3 mega bit each so that about 13 per AP.  That only about 15 AP.

lets look at the cost the Cat 6 Wiring install and tested you a looking a about $180 per drop $180 X 200 = $36000 not including switchs.  For say 15 high end AP $250 X 15 $3750.
0
 
LVL 1

Author Comment

by:egeiyioglu
ID: 13812742
Minmei,

I'm trying to avoid the cost of cabling the whole building as gjohnson pointed out.. I also want to use the freedom of wireless. Bandwidth is not so much of a problem for me, but every client getting a different ip address when they connect through different APs is a problem. thanks for the active AP hand-off tip, this should help. Say I've several APs as you suggest, is there a nice piece of software I could use to manage all APs from a central location? :))

I thank drnacboozway a lot as well. IT looks like I'll split the points between you guys (though a bit unevenly..)

So what type of a solution would load balance clients between APs?
0
 
LVL 6

Expert Comment

by:gjohnson99
ID: 13812769
With 802.11 standard the AP and Client will load balance by them self
0
 
LVL 27

Expert Comment

by:pseudocyber
ID: 13813611
IMHO, wireless is great for conference and meeting rooms, lobies, etc.  However in a static office environment, the best bang for the buck is wired - every time.  wireless won't be able to compete against wired for some time.  The best setup isn't an either/or - it's a both.
0
 
LVL 7

Accepted Solution

by:
minmei earned 2000 total points
ID: 13814486
Thank you pseudocyber!

802.11a has 12 non-overlapping channels, and 4 are reserved for outdoor use. 802.11a also has a smaller radius of effectivity - speed decreases greatly as you move outward - a wireless b signal may still be at 11mbps at 100 ft, an A signal won't be at 54mbps, more like 18 or 12 mbps.

Turbo mode is usually effective with 1 AP and 1 client and is not interoperable between brands of AP. Some turbo modes also get turbo by using additional channels.

802.11 won't balance by itself by a longshot. You will need a wireless solution where the AP's are controlled by a security switch that sits on your network. Cisco/Airespace, Trapeze, Aruba, and Nortel all do that, and I'm sure more do as well, but the one off AP's (Netgear/Linksys/Dlink) will not.

Most of the higher end AP's are more like $500 per and the Switches that control them can run up to $15K, so if 200 drops at $180 each = $36000, then 1 security switch and 16 AP's = $23,000. Still less, but with much less throughput.

Still your call - just wanted you to know what you were facing. Like I said before, I work for a wireless company - we install it, design it, and use it ourselves, just not by itself without wired lines.
0
 
LVL 27

Expert Comment

by:pseudocyber
ID: 13814544
Just want to add that any given AP operates at the speed of the WORST connection - because it's shared.  So, everyone is right by the AP and someone is on the border operating at 1Mb.  Guess what - everyone on that AP gets the 1Mb.

Also, if you go with some kind of speed booster, turbo booster, etc. you run the risk of not having clients seemlessly operate - since these are usually proprietary and require the vendors NICs as well as the AP.  Additionally, in my experience, hardly anyone has A cards.  Machines are coming with G built in - which can do G or B, but not A.  So, if you're thinking of visitors, VIPs, vendors, etc., then I would plan on G or A&G in the same AP.
0
 
LVL 79

Expert Comment

by:lrmoore
ID: 13814748
All good information, but if I were you, I would SERIOUSLY consider NOT getting rid of the wires. If you have full 10/100 switched LAN today, why would you want to choke that back down to a 10Mb HUB performance standard? If you have any quantification of the traffic that flows around your network today, not even 54Mb will come close to providing enough bandwidth. A lot of people don't realize how much bandwidth is used for things like print jobs. I've seen too many offices do what you are planning and then call people like me in to help them track down wierd network behavior, slow performance, application issues, etc. It has all boiled down to improper expectations of "going wireless".
There are perfect reasons to use wireless - all of them for laptops/mobile clients and "spot" application like confernece rooms, guest access, etc. If you have desktops, keep them wired. Printers will probably still be wired. Hopefully your servers will still be wired. You're still going to need switches to support the access points anyway.
0
 
LVL 7

Expert Comment

by:minmei
ID: 13815162
Encore!

If this is coming from a vendor, get them to show you an example. Heck - post a question here and ask for an example of an "all-wireless" installation so you can see how big and what kinds of things are done on it. If there is no vendor, get someone to come in and pitch you a solution - at least you'll have recourse if it doesn't work to go back to the vendor and get a settlement.

Wireless is a wonderful _extension_ to a wired network. It is not yet a wonderful _replacement_.
0
 
LVL 79

Expert Comment

by:lrmoore
ID: 13817945
Don't get caught like this guy did
http://www.experts-exchange.com/Hardware/Routers/Q_21394519.html

I have no idea how to help him..
0
 
LVL 6

Expert Comment

by:gjohnson99
ID: 13818175
Find some who konw what there doing.
We just move to a new building old bulding had large wireless netwofk 30-40 heavy uses wirless only users- work great.

New office been here over a year my  users still can't use it the wireless like they did in the old building  - A big vendor installed but dose not mean they know what are doing.  
0
 

Expert Comment

by:rizguy79
ID: 13821391
My teaher Rob Flickenger told this solution:::

check this out>>

Virtually all modern APs support roaming. Simply connect all of the
APs to the same Ethernet segment, set all of the APs to the same name,
and work out your channel plan as you normally would. Your clients
will automatically sense the strongest AP, and will hand-off between
them as they move around, changing to the proper channel as needed.

--Rob
0
 
LVL 27

Expert Comment

by:pseudocyber
ID: 13823085
Does your teacher also recommend 200+ users on wireless network only - no wired hosts?
0
 
LVL 7

Expert Comment

by:minmei
ID: 13823256
Yes, as you move within the building, when you lose signal strength from the AP you are associated to, the client will attempt to re-associate with another AP on the same SSID. if the security matches the old one, it will connect. It will reauthenticate and re-exchange keys. You will see the wireless connection drop, then come back, every time you switch AP's.

This does work, but the handoff time takes seconds because there is no mechanism for the AP's to know who you are from one AP to the other.

In a "roaming" config, there is software that controls the AP's that can sense the loss of signal from one AP, the gain of signal from another, and transfer the security records (key) of the client to the other AP and do a millisecond handoff without loss of connection and without change of IP. This is not default in any 802.11 a/b/g specification.

Channel changing is not the issue. Yes, most modern NICs will find the new channel as they scan for another AP to move to.
0
 
LVL 6

Expert Comment

by:gjohnson99
ID: 13824854
One thing that is cool about it. you can set it up in a fault tolerant way so if you lose AP or switch you will still be running.
0
 
LVL 79

Expert Comment

by:lrmoore
ID: 13828337
>My teaher Rob Flickenger told this solution:::
So, this was a homework assignment, not a "real life" scenario?
0
 
LVL 27

Expert Comment

by:pseudocyber
ID: 13830246
lr, that wasn't from the original questioner.
0
 
LVL 79

Expert Comment

by:lrmoore
ID: 13832619
ok. never mind.... <getting more coffee>
0
 
LVL 27

Expert Comment

by:pseudocyber
ID: 13832746
:D  Coffee ... gooood ...
0
 
LVL 7

Expert Comment

by:minmei
ID: 13832767
So, we've been pontificating (love that word) for a while.  Egeiyioglu, what else are you looking for?
0
 
LVL 27

Expert Comment

by:pseudocyber
ID: 13832783
I thought I was "waxing poetic" myself ... ;)

Yeah, Egeiyioglu ... sup?
0
 
LVL 1

Author Comment

by:egeiyioglu
ID: 13842561
thanks a lot guys.
I don't want to have it done through another company, I want to do it myself that's the problem :))

We have around 20 servers for various stuff and of course they are wired in our system room.
Other than that, other people all use laptops, we don't have any desktops in place and we don't plan to have any.

We have 2 networked HP color lasers and apart from that everyone who needs a printer has one on their desk..

I'm still insisting on doing stuff completely wirelessly :)

If someone could give me some model suggestions on the security switch and APs that could do milisecond handoffs, I'll have gotten all I wanted :)

thanks a lot again for the wealth of information you've provided.
0
 
LVL 79

Expert Comment

by:lrmoore
ID: 13842680
Suggested reading - Cisco's SWAN architecture handbook. Particular attention to the Wireless LAN solution engine product.

http://www.cisco.com/en/US/netsol/ns340/ns394/ns348/ns337/networking_solutions_package.html

0
 
LVL 7

Assisted Solution

by:minmei
minmei earned 2000 total points
ID: 13843068
WLSE may be _much_ too expensive.

Look at http://www.trapezenetworks.com or

the 2300 at http://www.nortelnetworks.com or

the 4000 series security switches from Cisco (used to be Airespace)
0
 
LVL 79

Expert Comment

by:lrmoore
ID: 13843394
>WLSE may be _much_ too expensive.
Perhaps, but the *new* WLSE-Express is geared more for SMB market..

Don't get me wrong, I'm not advocating any one solution over another, but just like with Cisco's SAFE blueprint, the SWAN blueprint is a great guide for what you need to support and maintain a wireless network of any size.

0
 
LVL 6

Expert Comment

by:gjohnson99
ID: 13844180
The cisco's stuff is what we have in are new building and in not work well. It has to this point be unable to stop rogue AP form running and are sysem.
0
 
LVL 7

Expert Comment

by:minmei
ID: 13844820
Airespace (Now Cisco 4000 series) rogue AP detection Rocks! We have it in two customer locations plus our office.
0
 

Expert Comment

by:rizguy79
ID: 13856233
Dear,

I am sorry for late reply.....
what i guessed you want to do all the stuff work wirelessly..... and ofcourse all the servers and printers etc should be avaliable to every authorised user....
morover i think its clear about how to use Encryption and multiple APs so that user can automatically switch to the nearest AP for best signal quality.......
the problem remained is whether it can support 200+ users????? so what u think one AP will support 200+ users or the load would be divided????

Dear can you please elaborate that:
    *At one floor how many APs of which model you want to place
    *How many users on average would be on same floor at a time??? and maximum load expected at on AP??

all the APs will be connecteed via UTP to the servers and printers so no need to worry about that part......
0
 
LVL 1

Author Comment

by:egeiyioglu
ID: 13902205
The users are scattered uniformly.. There are around 50 users on each floor. The maximum could be 100 users on a single floor and not more than that. I need a solution that would do load balancing across APs so that a single AP does not have to handle 50 users and its neighbor sit idle :))
0
 
LVL 6

Expert Comment

by:gjohnson99
ID: 13902764
As has been stated the AP do the load balancing

Also I would keep the users per AP to

B/G = 5

G or A only 7

G or A turbo 13

If you want happy users

using B/G you will not be able to have the number AP need to cover the area

B/G  3 usable channels

A  14 + Usable channels





0
 
LVL 7

Expert Comment

by:minmei
ID: 13906634
If you look in my first reply, you can see how B or G can cover an area without overlapping channels ...
0
 
LVL 79

Expert Comment

by:lrmoore
ID: 13917056
Site survey... site survey....site survey....

http://www.cisco.com/en/US/products/hw/wireless/ps4555/products_installation_and_configuration_guide_chapter09186a008007f8f1.html

You gotta do the legwork... and it *is* a very labor-intensive tedious job.
0

Featured Post

Free Tool: Site Down Detector

Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article is a collection of issues that people face from time to time and possible solutions to those issues. I hope you enjoy reading it.
This article explains the fundamentals of industrial networking which ultimately is the backbone network which is providing communications for process devices like robots and other not so interesting stuff.
Internet Business Fax to Email Made Easy - With  eFax Corporate (http://www.enterprise.efax.com), you'll receive a dedicated online fax number, which is used the same way as a typical analog fax number. You'll receive secure faxes in your email, f…
This video gives you a great overview about bandwidth monitoring with SNMP and WMI with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're looking for how to monitor bandwidth using netflow or packet s…

578 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question