Best WAP For Dense Crowds? 178
An anonymous reader writes "A local community organization has asked me to help them set up Wi-Fi access for an upcoming event, with some unusual (to me) requirements. All users (up to 500 people) will occupy a relatively small area and more-or-less have line-of-sight to the WAP, so issues like signal strength and wall penetration don't matter. Security also does not matter, as we plan to open this to anyone wanting to connect. Cost always matters, but we realize a $50 Linksys or three won't cut it here.
In the past, I have used Cisco AP1200s for a few dozen users to great satisfaction, but they only handle 50 connections at a time, and practically count as antiques at this point anyway. My research on the matter tells me that 802.11n performs far better in this regard, but I want to support 802.11g as well. I have no objection to using two APs to split those apart (with n limited to 5.8GHz, as per the suggestion of several comments in a recent Ask Slashdot), but physical constraints make it preferable to minimize the total number of APs needed — Ten WRT54s might cost about the same as one Aironet, but I only have three good places to mount these.
I welcome any suggestions and real-world experiences with similar situations, including the ever-popular Ask Slashdot refrain of 'What kind of idiot would do it like that, when you can just do this?' Ideally, I would like to know model numbers and how well they held up under real-world loads comparable to my situation."
how cheap? pfsense? (Score:5, Informative)
consider running a small pfsense box with a number of wifi adapters. You could pick up some cheap directional antennas to help limit connections to any one radio somewhat. Alternatively you could just run 4 sids and do a script to hide a sid when the user count got so high so the next users would only see the less loaded ones.
you will need more than 2 APs (Score:5, Informative)
there was a slashdot the other day about the wifi at a python conference.
any AP is only going to handle 50 users or so because 802.11x is contention based.
So go ahead and get yourself 10 APs, spread them out, and make sure the ones near eachother are on different channels.
Re:how cheap? pfsense? (Score:5, Informative)
I might add that you are going to be stuck with 4 channels ( 1,4,7,10 ) which means that 500 people will be hard to support without highly directional antennas. Maybe try to split the space into 4 with directionals.
Re:WAP? (Score:5, Informative)
sounds like Xirrus. But I'd recommend... (Score:2, Informative)
But I'd say, a few Aruba AP-105s [arubanetworks.com] (with 802.11abgn and band steering - which tries to put clients on the 5Ghz band), or maybe even AP125s [arubanetworks.com] (which have more MIMO) for the core. You can fill in the corners with cheap little AP-65s [arubanetworks.com]. The ARM (adaptive radio management, shoves clients from one AP to another or something like that) means that Aruba works very well in dense deployments. (You'll also need a controller behind them... probably an Aruba-200 or a 651 - the latter has a built in AP. Having the controller limits the configuration you'll need to do.)
I work for Aruba, but I never look at a price list. I believe, however, the pricing should be rather competitive with Cisco .... Also, I'd cite some super awesome deployments and customers but I forget who's a super awesome reference customer that my parents would recognize and who's just "a major hospitality win in the Middle East" (which is so much less impressive-sounding!) here's their press release page anyway [arubanetworks.com].
Asus RT-n16 (Score:3, Informative)
Run your favourite 3rd party firmware on it (openwrt, dd-wrt, tomato, whatever) - it's specs are pretty awesome for the bucks. 128M Ram, 32M flash, two usb ports, N wireless, 480Mhz Broadcom/MIPS cpu (~twice as fast as most others).
Re:Mikrotik a possible choice? (Score:4, Informative)
p.s. if running cables is a problem... (Score:2, Informative)
and here's the press release about the Australian Open [arubanetworks.com], whose organizers said
Aerohive (Score:1, Informative)
You may want to look into Aerohive. If you are interested in pricing or more technical information let me know http://www.aerohive.com/products/overview/hiveAP300.html
Comment removed (Score:5, Informative)
Not cheap, but... (Score:5, Informative)
Re:how cheap? pfsense? (Score:5, Informative)
I did a little googling because I was worried about the number of clients. 802.11 uses CSMA which means that every client must wait for every other client to go silent before transmitting.
That means that you would have to take the minimum latency and multiply it by 500 since all clients will be equals. That puts you into 500ms of theoretical latency per packet.
What this means practically is that with 500 clients using all roughly the same bandwidth at 54Mb (unrealistic BTW) you would have just 110Kb per second available to each with 500ms+ latencies, which will compound exponentially.
Though on paper you might be able to show that ability to connect this many clients but realistically, on HIGH end hardware your are going to have a 50 client MAX simply because of CSMA requiring everyone to take turns but less any bandwidth sharing.
To make things worse, the amount of data having to be moved just to keep everyone connected and to communicate who is 1st,2nd,3rd, etc in line to speak is going to cut your bandwidth to a tiny fraction of the link speed.
I highly suggest that you take one of the early poster's advice and drag some cat5e around. You might have some lucky with 'CELLS' of WRT54g type routers with a carefully selected channel scheme where a set of 4 routers would have channels 1,4,7,10 and the next closest 2,5,8,11 and the next 3,6,9 and then start over. The channels will overlap somewhat but having 11 SSIDs for 500 people even with some channel interference would get you to somewhere around 50.
you could extend that to put some 5Ghz band routers in each router bunch and hope that people are fairly evenly split between G and 5Ghz N
Meraki (Score:3, Informative)
Seriously, try Meraki. Their software is pretty neat, and it'll auto configure to give you the best situation.
A case study: http://meraki.com/general/2009/12/09/does-it-scale [meraki.com]-absolutely-blazing-fast-meraki-wireless-at-leweb-conference-in-paris/
consumer equipment is the wrong answer (Score:5, Informative)
Background on me to qualify my comments: I am a cisco engineer specialising in wireless and security. My product recommendations later come from this experience but there are other products capable of the same performance such as the aruba equipment which would be my close second recommendation but i have no specific product knowledge.
I think you need to refine your requirements. It is highly unlikey that a crowd of 500 people will create 500 connections. You will probably end up serving 100-150 clients simultaneously but not all of them requesting data at the same time unless there is something specific that all users need to connect to at the same time throughout the event.
Without much better information everyone is just throwing out a product, not a design. And as you clearly are not a wireless expert (as you asked for 802.11n "as well as .11g) i would recommend finding someone who is to consult properly.
And for those suggesting consumer products, your dreaming. Without some form of spectrum management in this situation the asker is doomed to provide a very poor service with no roaming and massive 2.4ghz congestion. In addition, those people recommending wired access, WTF? You very clearly do not understand what you are talking about. Are you expecting 500 desks with RJ45 ports, or multiple 48 switches places around the room for people to huddle around with their laptops (and only laptops as no mobile device even has an RJ45 port). This is clearly a fallacious argument.
Answer the following questions and we can all get very specific.
3 points to place APs. Is this to physically mount or a cabling limitation? Can you mount more but have no cabling? Un-manged switches can help with this for less than $50 each. If only to mount then you are stuffed, There is nothing out there that will handle 500 clients with any useful service. It's not a limitation of the products it's the contention of the medium as mentioned earlier.
What services are they accessing? Are they local or is it just the internet? If the internet, what is the upstream bandwidth available? If local access at high speed (100Mb/s +) then you will end up with contention issues. If it is the internet and the pipe isn't fat you are not looking at contention issues you are looking at number of users connected. Most modern APs do not have practical limits of associated clients but most recommend around 25 per AP.
What is the nature of the event? Basically, are you providing a service that is required constantly throughout the event leading to 100% of attendees connecting all the time. Also, are users accessing a high bandwidth service (streaming video for example) all the time or things like static web pages delivered via http? The later will deliver small amounts of data to each person but will then take time to read by the attendees al will also be cached locally meaning subsequent connections will require even less bandwidth. If streaming video, someone should have though of this earlier and you will need a consultant/engineer 100% or expect to fail.
An off the cuff answer without the above knowledge assuming http type data required, cabling limitation not mounting, the more realistic 150 simultaneous users and internet link at less than 30Mb/s:
1x Cisco 2112 Controller (100Mb ports not important as limited upstream)
5-9x Cisco 1142 APs (very nice 802.11n dual band with the ability to force people to move to 5Ghz if they have it 6.0+ code)
3x gigabit unmanaged switches (something like dlink DGS-1005D)
It would not be far fetched to contact decent size Cisco/Aruba/VendorX partner and get loan equipment for a price + a consultant as part of the deal.
Aruba Networks = Wireless Win (Score:2, Informative)
The chains of Cisco are removed, and an extraordinarily simple setup process - which will help you figure out AP placement and type, after uploading a site map, including all sorts of calculations that I'd really have a computer do.
I seriously recommend you take a serious look at Aruba Networks offerings.
Seriously.
Re:Not cheap, but... (Score:3, Informative)
I'll second the Xirrus arrays. They're absolutely amazing for high-density wireless. If it's a one-time event, you may be able to get Xirrus to sponsor it by providing the gear, especially if it's a gathering of geeks.
My Pick (Score:2, Informative)
Re:you will need more than 2 APs (Score:5, Informative)
Re:Use ALL 14 WIFI channels ! (Score:3, Informative)
You can't use all the channels due to overlap / interference. 1,4,7,11 OR 2,5,8,12 - BUT - the issue is going to be how they are allocated. If everyone tries to connect to the same AP / channel, it's still not going to work. You solve this by using directional "sector" antennas. However, these cost a small fortune. Best bet in THIS application, with budget constraints, is to use decent commercial AP's on 4 different channels around the middle of the corners of a 3x3 grid and hope that user devices will pick AP with the strongest signal. The number of devices that support 5Ghz is soooo limited right now that a single device at that freq in the middle is probably all that is needed. Hopefully this changes over the next few years and we get more 5Ghz adoption.
Precise placement and number of units, etc., depend on the details of the space, and for that you pretty much need a walk-through.
Depending on usage, etc., be prepared for crappy performance anyway since whenever you have tons of devices all working on the same frequency range. It's going to suck no matter WHAT you use because all the devices will be somewhat chatty and interfere with each other. Remember - it's not just communication between Bob and the AP - you have all of Bob's neighbors interfering with him too - even if you had a super-highly directional antenna pointed right at his laptop, Bill, Lisa, Frank, Biff, Buffy etc. etc. sitting at the same table as Bob will be interfering with his communications since they are NOT directional (and neither is Bob.)
Re:Use ALL 14 WIFI channels ! (Score:2, Informative)
There is only so much spectrum. Either force everyone to N-only or tell them the WiFi might not support everyone. You can only use channels 1, 6 and 11 in 2.4GHz due to overlap of the other frequencies. Look at figure 10 in this paper that studied throughput vs. channel overlap. [upc.edu]
Only one vendor can do this right... (Score:3, Informative)
- Band Steering: Use dual-radio access points. The Aruba gear detects if a client supports both 2.4g and 5g, and moves the client automatically to the 5g band, which is cleaner and has more channels available.
- Spectrum Load Balancing: Every vendor offers load balancing: there are 10 users on AP-1/Channel 1, and 20 on AP-2/Channel 6, so put the next user on AP-1. This ignores the fact that the only resource you're really constrained by is the amount of spectrum in use, not the number of users on an AP. If those 10 users are using most of the spectrum of Channel 1, while Channel 6 isn't being used as heavily by the 20 users, you'll get better performance by balancing the user to the less-utilized spectrum, rather than the lowest user-count AP.
- Co-Channel Interference: The Aruba architecture knows when a client is within range of two APs on the same channel, and schedules transmissions out of the APs so they don't collide in the air.
- Adjacent channel interference: Aruba ecognizes that there *will* be some bleed between transmissions on adjacent channels, and manages transmissions to avoid that.
- Airtime Fairness: Aruba recognizes the different client phy types (802.11a, b, g, and n-2.4/n-5) and allocates certain amounts of airtime to each client, so those old 11b clients don't drag your 11n clients to a screeching halt.
- Channel Reuse: modifying the collision threshold on the channel to allow you to reuse channels in much closer proximity to one another than normally possible.
- Dynamic Multicast Optimization: The APs can detect a multicast stream and determine if it's better to send the stream to all multicast clients at one, but at the normal lowest data rate, or convert the stream to a series of unicast transmissions that can be sent to each client at a much higher rate.
- Mode-aware Adaptive Radio Management: Deploy as many APs as you want. The Aruba architecture will automatically turn on (or off!) individual radios based upon RF needs; too much RF is worse than not enough, in most cases.
- Client bandwidth contracts: Set a rate limit for each user, so one person can't use half your bandwidth.
- Policy Enforcement Firewall: Allow your users to only do what protocols you want (http, https, dhcp, dns), and block all the others. iTunes/Bonjour/MulticastDNS from Apple products will KILL your network otherwise.
If you want more information on the physics of these methods, check out this white paper which has more info than you'll want to read:
http://www.arubanetworks.com/pdf/technology/whitepapers/wp_ARM_EnterpriseWLAN.pdf [arubanetworks.com]
Now, all of that said, here are some BAD ideas that people have suggested:
- Use all 14 channels!
------ Not only is this illegal almost everywhere, but most clients will use the operating system's country code and only use the channels that are supposed to be available. In the U.S. for example, only channels 1-11 are valid; client devices won't try to use channels 12-14.
- Use channels 1, 4, 7, 10 on one group of APs, then 2, 5, 8, 11 on the next set....
------ TERRIBLE idea. Because 802.11a