• RSS
  • Twitter
  • FaceBook

Security Forums

Log in

FAQ | Usergroups | Profile | Register | RSS | Posting Guidelines | Recent Posts

help me design a wireless network

Users browsing this topic:0 Security Fans, 0 Stealth Security Fans
Registered Security Fans: None
Post new topic   Reply to topic   Printer-friendly version    Networking/Security Forums Index -> Networking

View previous topic :: View next topic  
Author Message
moondoggie
Lurker
Lurker


Joined: 27 May 2005
Posts: 19


Offline

PostPosted: Wed May 11, 2011 11:12 pm    Post subject: help me design a wireless network Reply with quote

i have a client who has two large rooms currently serviced by four WAPs, two upstairs and two downstairs. they have many problems associated with hosting events in their rooms, namely that people have dropped connections or some can't connect at all. right now they have a combination of four total HP ProCurve and 3Com PoE access points but they continue to have issues. at any given time they may have from 40-150 people trying to use wireless throughout the facility and they are asking me to redesign their network so that they do not continue to have problems.

my thought was to put a separate router on the upstairs and downstairs networks, but i would also like to replace their current WAPs with something extremely reliable that can also handle the bandwidth requirements. can anyone recommend a WAP that has PoE which can handle the kind of situation i've described? or make a recommendation that i am or am not heading the right direction with what i have planned. any useful input is greatly appreciated. Smile
Back to top
View user's profile Send private message
moondoggie
Lurker
Lurker


Joined: 27 May 2005
Posts: 19


Offline

PostPosted: Thu May 12, 2011 5:56 pm    Post subject: Reply with quote

that doesn't actually help my situation. this is basically a guest wireless network for events and needs to be able to handle the equivalent of a small convention every week. a leased line is not going to solve anything we're having problems with.
Back to top
View user's profile Send private message
krugger
SF Mod
SF Mod


Joined: 08 Jun 2006
Posts: 16777209


Offline

PostPosted: Thu May 12, 2011 6:13 pm    Post subject: Reply with quote

Do you have a WLAN controller?

Each WAP should take about 30 people, so a floor with 140 people should be ok with 4 WAPs. Altough you should check how many people can connect at the same time. The problem might be all WAP operating on the same channel.
Back to top
View user's profile Send private message
moondoggie
Lurker
Lurker


Joined: 27 May 2005
Posts: 19


Offline

PostPosted: Fri May 13, 2011 10:03 am    Post subject: Reply with quote

the current network is configured as:


router -> managed PoE switch -> 4 WAPs


what i would like to do is:

router#1 -> managed PoE switch -> upstairs WAPs
router#2 -> managed PoE switch -> downstairs WAPs

also, the current configuration is two upstairs and two downstairs WAPs. each floor is a different group of people, each with 40-150 at any given time. if 30 per WAP is the de facto standard, we are seriously overtaxing the system Shocked
Back to top
View user's profile Send private message
krugger
SF Mod
SF Mod


Joined: 08 Jun 2006
Posts: 16777209


Offline

PostPosted: Fri May 13, 2011 3:11 pm    Post subject: Reply with quote

I was asking about a WLAN controller because that should help the AP cooperate and give you some more information on the problema and statistics. But from Cisco Aironet 1200 deployment FAQ:

Q. How many clients can associate to the AP?
A. The AP has the physical capacity to handle 2048 MAC addresses, but, because the AP is a shared medium and acts as a wireless hub, the performance of each user decreases as the number of users increases on an individual AP. Ideally, not more than 24 clients can associate with the AP because the throughput of the AP is reduced with each client that associates to the AP.

So you need more Acces Points if they are like these ones, but your hardware manual should have something about the number of clients per WAP. Some highend Procurve WAP say they support 250 clients, although it might just be marketing. Razz
Back to top
View user's profile Send private message
Weaver
Trusted SF Member
Trusted SF Member


Joined: 04 Jan 2003
Posts: 0
Location: WI, USA

Offline

PostPosted: Fri May 20, 2011 4:36 am    Post subject: Reply with quote

When sizing for wireless users it is important to distinguish between capacity planning at various layers. OSI aside, there are several layers to consider:


  • Physical Spectrum Capacity and the 802.11 PHY and 802.11 MAC Layer - Books have been written about 802.11a/b/g/n spectrum planning and design. Simplifying much technical analysis boils down to the following -- number of wireless stations, throughput required by the stations, interference/noise, and attenuation. Most problems with high density WLAN's are manifested here. As the WLAN stations increase in density, the amount of time spent here planning should also increase.
  • Wired Network and Internet Capacity - This is fairly familiar territory for most network engineers. Is a DS1 enough for 100 laptops and 25 iPads? No.
  • Enterprise Grade (even Carrier Grade) Hardware - Not all hardware (especially when it comes to access points and radios) is created equal. The ability for "OEM-random" access point to effectively, quickly, and reliably handle 25 wireless stations should not be taken as a given.


As far as recommendations are concerned --


  • First and foremost use at a minimum enterprise grade hardware. Do not cheap out on access points -- just don't do it. The venerable Cisco 1130AG (indoor office) and Cisco 1240AG (rugged/challenge RF) are top notch 802.11a/b/g access points. For 802.11n the Cisco 1140 (indoor office) and Cisco 1260 (rugged/challenge RF) are great choices. The state-of-the-art (as of now) is in the Cisco 3500 series supporting "CleanAir" which is Cisco Marketing-speak for including spectrum analysis hardware inside the access point itself allowing the access point to isolate, avoid, and communicate interference back to the wireless control system.
  • Use a centralized/controller ("Unified" in Cisco speak) based wireless LAN system. This at a minimum will involve a wireless LAN controller (WLC) and may involve a controller for the controllers (WCS in Cisco speak) if you get big enough. At a minimum WLC's offer central administration of that which they control. Cisco's WLC's offer what is dubbed as radio resource management (RRM) -- a set of capabilities and features that maximize the use of spectrum by dynamically sizing transmit power levels on access points, among other things.
  • In very high-density station areas, consider reducing your cell size by intelligently placing more access points and reducing your transmit power on the access points. Cisco refers to this as "pico cell" mode and allows for more access points, stations, and combined throughput in the same volume of physical space when deployed properly.


I'll stop now as I feel like this is turning into an advertisement for Cisco wireless products. I have not used HP or Juniper wireless solutions. 3Com (prior to HP buyout) was fine for small environments on a budget but would not use in high-density cells. I have heard good things from fellow engineers using Aruba gear but can't speak firsthand.

-Weaver
Back to top
View user's profile Send private message
moondoggie
Lurker
Lurker


Joined: 27 May 2005
Posts: 19


Offline

PostPosted: Fri May 20, 2011 6:42 am    Post subject: Reply with quote

I appreciate the insight, but the client is not going to approve all new cisco equipment just yet Smile i will keep it in mind, but i'm pretty sure they're not going to go for it. they would prefer to keep their existing equipment if possible.
Back to top
View user's profile Send private message
Weaver
Trusted SF Member
Trusted SF Member


Joined: 04 Jan 2003
Posts: 0
Location: WI, USA

Offline

PostPosted: Fri May 20, 2011 4:54 pm    Post subject: Reply with quote

As the consultant, MSP, or friend it is your professional obligation to determine the "correct" solution and work with the client to have it implemented.

Whether that solution is making better use of existing hardware, software, and licensing or involves the purchase of one or many additional pieces of hardware, software, and licensing is up to you. As a consultant this is precisely for what you are paid -- your expertise in solving problems.

The problem your client is facing *may* be solvable with existing infrastructure. However, with what information I have read it appears as if the wireless infrastructure is an "autonomous" wireless infrastructure.

The problems you describe and the solutions to the problem you describe have been developed -- in the form of "centralized/controller/unified" wireless infrastructure which includes such vendor agnostic concepts as centralized management and configuration, radio resource/spectrum management and others.

Whether your wireless vendor is HP, Juniper, Aruba, or Cisco -- these vendors have solutions for your problem -- called by different marketing and product names.

The concept is the same -- move from an autonomous to centralized model and benefit with reduced management, increased capacity, and increased reliability.

-Weaver
Back to top
View user's profile Send private message
Sheena
Forum Fanatic
Forum Fanatic


Joined: 24 Jun 2011
Posts: 16777215


Offline

PostPosted: Fri Jun 24, 2011 10:33 am    Post subject: Reply with quote

hey buddy i am new to this field so dont know so much about the wireless network ... i am here to learn more from you people .. hope that you all will help me out . Smile
Back to top
View user's profile Send private message
AdamV
SF Mod
SF Mod


Joined: 06 Oct 2004
Posts: 24
Location: Leeds, UK

Offline

PostPosted: Fri Jun 24, 2011 10:46 am    Post subject: Reply with quote

Weaver wrote:
In very high-density station areas, consider reducing your cell size by intelligently placing more access points and reducing your transmit power on the access points.


This is particularly important - you need to figure out what the coverage area is for each of the four APs at the moment, and if it is overlapping too much.

Four APs says to me that at least two of those must be on the same channel, so you want to make sure they are as far apart as possible. Neighbouring (or overlapping) APs need to be using channels as far apart as possible, so 1, 6, 11 or 1, 7, 13 (depending on your country's regulations).
Some "high bandwidth" APs will be using more than one channel at once which can make this situation even more important to check out.

As number of connections to an AP increases, everyone gets a smaller and smaller slice of the cake (only one station can actually communicate at a time, in tiny time slices). Only way to really increase throughput is to use more APs, which means more care taken over placement and transmit power.

Bear in mind that even if you tune the transmit power of your APs so they don't interfere with each other, the clients may still be turned up to the max and interfering with each other when they are connected to different APs on the same channel.
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   

Post new topic   Reply to topic   Printer-friendly version    Networking/Security Forums Index -> Networking All times are GMT + 2 Hours
Page 1 of 1


 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

Looking for more Windows Networking info?

Sign up to the WindowsNetworking.com Monthly Newsletter, written by Enterprise Security MVP Deb Shinder, containing news, the hottest tips, Networking links of the month and much more. Subscribe today and don't miss a thing!
View a sample newsletter.

Become a WindowsNetworking.com member!

Discuss your Windows Networking issues with thousands of other Windows Newtorking experts. Click here to join!

Community Area

Log in | Register

Readers' Choice

Which is your preferred data recovery solution?

Follow TechGenix on Twitter