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."
Best WAP For Dense Crowds? (Score:5, Funny)
You don't have to hit 'em, mate. Just find another crowd that's brighter.
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I tagged the article "open handed slap"
What's the event? (Score:4, Insightful)
Will all 500 users connect at the same time and continuously (like some type of LAN party w/o the LAN) or is this much more haphazard and random with far less users at any one time?
Re:What's the event? (Score:5, Funny)
And why wasn't I invited?
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A story about crazy behavior at a party (Score:2)
was meant to be a story about crazy behavior at a party:
"Come on, man... After the last time... The lamp shade, two Chihuahuas, and the weed whacker, do you really have to ask?"
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There seems to be an echo in here.
Oh, and please compare:
waker [google.com]
wacker [google.com]
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the lamp shade, two Chihuahuas and the weed waker,
The Weed Waker - isn't that the new Zelda game?
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Simple: Bad ping.
Seriously? A WLAN party? What next? Wireless mice and keyboards?
Good luck hitting me before I rip you apart with my connected-by-wire devices. ^^
Because you ain't dense. or are you? (Score:2)
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.
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.
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You might want to select USB wireless devices that have as much of the firmware running in the host as possible to avoid overloading the little microcontrollers that are built into the radios. You might also want to have a bunch of cat5 cables hanging around the perimeter of the place in case people who need the net cant get it wirelessly.
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
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
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they have been getting best-in-class service.
I hate this phrase. Is the service class they are getting First Class, Coach, or Baggage? Every MarketingDroid who uses this phrase never says which one...
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Probably Sewer Class...
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Use simultaneous dual band APs. Push everyone possible to 5Ghz.
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
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i would mod you up had i not already commented
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Yes, we should be able to mod people up to remove our comments.
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Re:how cheap? pfsense? (Score:4, Interesting)
Re:how cheap? pfsense? (Score:4, Interesting)
This is the thing, more than one problem to deal with in the same physical space. Cheap AP equipment may give you issues under load. With just a couple connections a cheap Linksys will work fine, push the load on it and I find that performance degrades exponentially with traffic increase. Home routers are not built/designed for business loads, or 500 user environments.
The problems: limited mounting space, limited frequencies, limited to mix mode, client movement, (re)registration issues and so on.
Since none of us know the exact physical construct of your problem, suggestions of directional antenna systems, alternating channels etc. have to be used. Cellular systems work in similar ways. 11g mode pointing north/south on chan 2 and 8, 11g mode east/west on chans 5 and 11, ne corner with chan 3 etc etc etc. The low tech testing/wardriving to find the right power levels is a solid suggestion, though this might limit your choices of AP equipment. Pick AP gear that can give you flexibility with antenna systems, power levels, op mode and channel settings.
You will also have to adjust your planning to account for movement of clients. If they are likely to move from ne to se physically, will they need to re-register? Is that a problem? It takes a lot of thinking to get this job done. Enterprise gear will take you toward meshing, and on the pricier end of things move the control out of the AP to allow better performance independent of physical movement.
All of this can get a bit trickier if you have multiple floors with large signal loss between floors. At that point, antenna systems become a stronger tool. At some physical point you'll find clients seeing enough sig strength to end up bouncing on/off one ap and off to another, then back again, never really staying registered long enough to do any good. There you have to fine tune signal strength. Some of the higher end meshing gear gives you options to deal with that, but that becomes a budget issue.
Start with your fixed constraints, evaluate how fixed they are. With some antenna systems, you might find that you have room in more than three places to use APs which would dramatically change your overall problems. The actual AP gear you choose will help discern what you can do about the remaining problems. Don't be afraid to call a sales/marketing engineer for advice, it's usually given free at some level of interest. That's not even to mention this: http://lmgtfy.com/?q=how+to+set+up+mesh+mode+wireless+networking [lmgtfy.com]
I think that the process of trying more to understand what the real problems you will have is going to help you further figure out what you need to do.
One last thought, an extra 1500 bucks on the limo now is a lot less than you would spend to find one ready to go on prom night, so to speak. Read to see what the equipment on your short list does under load, how it works in high volume situations etc. that lmgtfy link might show you some good examples to read about.
Re:how cheap? pfsense? (Score:5, Insightful)
And that's a pretty serious problem. In my experience (which admittedly is mostly as a user, not an admin), most OSes aren't happy with high-latency wireless networks. With a fast, low-latency network with no packet loss, it can take a couple of seconds to do a DHCP request. With a slow, high-latency link with packet loss, I've seen it take a couple of *hours* to do a successful DHCP request. Sadly, such connections are easy to get when you have a few dozen people on an AP downloading porn^H^H^H^Hmovies^H^H^H^H^H^Hlegitimate software bits.
Something you might do to alleviate this is to use the 10 network for all your access points. Never reuse IPs and set your DHCP server to cache IP assignments and always ack when a host requests to extend its assignment. Oh, and set the lease time to a month or something. Doing this should reduce the number of DHCP packets that have to be sent. IIRC, for a re-request, you're down to one packet in each direction instead of (at least) two in each direction. Of course, if you can't get the response back within about two seconds, the client is likely to give up and fall back to a full-blown DHCPDISCOVER....
You should probably use a fast switch with a fast backbone between the APs and your core router/DHCP server to minimize latency between the AP and your DHCP server.
I would not use the same machine for the upstream router and the DHCP server. By keeping those separate, you are further reducing the wired portion of your latency because your DHCP discover/request packets aren't getting backed up behind outbound network traffic on the wire. Be sure to use a reasonably fast box for the DHCP server and a FAST box for your router/firewall/NAT box. Do not, under any circumstances, use the NAT built into any consumer router boxes.... The CPUs just aren't anywhere near fast enough.
Get several radios going, crank the gain down as much as is practical without losing bars of signal as seen from the devices, use directional antennas to dice up the space into as many distinct zones as possible, and organize the zones to maximize the distance between APs on the same channel. I'd probably put external antennas spaced periodically down each wall in alternation, forming a series of alternating cone-shaped zones. The exact distances depend on the spread angle of the antenna and the width of the room. Alternatively, you might consider hanging them from the ceiling pointing down, spaced in a grid formation.
If you can, try to make your APs give top priority to DHCP messages, thus minimizing the number of these packets that get dropped before they make it out (in either direction).
Oh, yes, and turn off 802.11b support if you can. Allowing 802.11b means that every packet sent at high speed requires additional crap before and after it so that the 802.11b radios don't choke. If that's not possible, set up a separate segregated network for legacy 802.11b clients and stick it on its own channel---probably one AP for the whole room.
Finally, if at all possible, make sure your DHCP server sends ACK using unicast where possible. AFAIK, every major OS should be able to handle this. IIRC, broadcast packets on 802.11 are particularly expensive. The more you can minimize them, the better off you are. While you're at it, crank up the multicast rate (basically, the minimum signal level that a client must maintain before the AP throws you out). This will force clients to associate with new stations more frequently, but should increase network performance and decrease latency under (particularly multicast/broadcast) load.
Oh, and one more thing. I'd like to echo the comments about not using home router gear. Get yourself Cisco APs. Most home routers just don't have the CPU to keep latency low enough when routing that much traffic, and many don't have sufficient control over power levels, external antenna jacks, etc.
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a few dozen people on an AP downloading porn^H^H^H^Hmovies^H^H^H^H^H^Hlegitimate software bits
I'm about to buy me a double barreled sawed off shotgun and show Linus what I think about backspace and delete not working.
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DHCP (Score:2)
> Finally, if at all possible, make sure your DHCP server sends ACK using unicast where possible. AFAIK, every major OS should be able to handle this
Windows Vista by default (stupidly/evilly pick one) sets the broadcast flag for DHCP, so it requires broadcast responses. While it can handle unicast replies if configured accordingly, by default it doesn't ask for unicast replies and thus should not be getting unicast replies.
See: http://support.microsoft.com/kb/928233 [microsoft.com]
Windows 7 probably handles it better: h [technet.com]
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Windows Vista by default (stupidly/evilly pick one) sets the broadcast flag for DHCP
The first time I read that, I saw "sets the broadcast flag [wikipedia.org] and HDCP [wikipedia.org]". Perhaps I just have DRM on the brain.
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In many of the possible futures you will have DRM in the brain.
After all once they start adding "videographic"+"audiographic" memory as an option, or even mere photographic memory, the Media Monopolizers will start requiring that either you get crippled in order to watch a movie, or you use brain augmentation that has DRM in it.
Then it'll be not a penny for your thoughts, it'll be USD0.99 to recall "their" stuff.
Good luck trying to share experiences with your friend
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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.
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He's only got physical room for three access points (or, more likely: three clusters of access points).
There are three non-overlapping channels. So, 3 channels * 3 clusters = 9 APs, maximum. But 9 APs * 50 users each 500.
It's important to remember that 50 is just a useful number, and needn't be a hard limit: It's not spelled out in 802.11 that "there shall not be more than 50 users per node."
And besides, it's not like folks are going to physically locate themselves for optimum WiFi distribution. They'l
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And besides, it's not like folks are going to physically locate themselves for optimum WiFi distribution. They'll be wherever they are.
They will if they are any sort of nerd who has done any wardriving. Don't tell me you have never held your laptop vertical in just the right spot out the car window to get a connection.
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Well, sure I have. Just like any other self-respecting geek.
But we're a pretty small cross-section, and this task seems to involve a more generalized crowd.
Re:you will need more than 2 APs (Score:5, Informative)
Mikrotik a possible choice? (Score:5, Interesting)
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mikrotik is cheap, and flexible, and can do lots of things, but there are lots of advanced features that only work half way, half the time, or are half-way documented.
if you are going to keep it simple, or don't mind spending hours reading old forum threads then it might be the way to go!
Re:Mikrotik a possible choice? (Score:4, Informative)
Choices (Score:4, Interesting)
I have a Netgear WNDR3700 that I use as an access point. It has a lot of good features including two independent radios (2.4 and 5 GHz), gigabit switch and a pretty fast processor. It is about as good as it gets for hardware of its type.
The firmware based on OpenWRT. Some of the features like the attached storage are dodgy, but that doesn't matter for this application.
For your application though - high density, lots of users why don't you take some of the load off the airwaves by offering wired connections too? People who aren't actually physically roaming will appreciate the choice and better performance of wired.
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).
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The RT-N16 is 2.4GHz only which will be terrible for this scenario. The OP needs to use dual band routers to utilize both bands and maximize the number of clients that can be supported in a small area. 2.4GHz only has 3 non-overlapping channels and if you figure 50 per channel then that's 150 users for 2.4GHz. The 5GHz range has far more usable channels and the majority of N adapters can utilize either band.
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Turn down the TX power Re:Asus RT-n16 (Score:2)
Use more WAPs and adjust the TX power down - then you can have greater density.
Comment removed (Score:5, Informative)
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I've been really disappointed with Aruba. Our office runs on Aruba access points + controller. Coverage is universally bad even quite close to the access points, and there are occasional drop-outs. Maybe I'm just not smart enough to set it up properly.
Not cheap, but... (Score:5, Informative)
ballroom surfing (Score:3, Funny)
So you put 240 people in a single ballroom, and all they do is surf the web?
Why..? Did you forget to turn on the music?
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239 of them are male, and the 1 potential "other" has a mustache.
Anyway, joking aside, have you seen kids today in a net cafe or Starbys ? Even when they're there with friends, they don't talk to each other, they IM each other via Facebook.
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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.
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I read bathroom and started to wonder...
Me too... (Score:2)
My brain got hung up on that thought for a while trying to figure out if it would even be possible to fit that many devices in my bathroom.
Re:Not cheap, but... (Score:5, Insightful)
The parent means Xirrus will cause the event organizers to mortgage a house. Still, Xirrus can have tons of radios in one device, all with segmented antennas, and they really are a good fit for this kind of stuff. They even have a pole/tripod mounting option where you can set up more if need be. See about the sponsoring or maybe renting.
Alternatively, get external 60 degree segment antennas for something like Cisco 1250s and do hexagonal cells, like wireless carriers do. For dual band MIMO you need six antennas per AP, so it'll get out of control mighty fast.
Worst case, get a bunch of APs, have three of them use the three 2.4 GHz channels with MIMO (but no channel bonding!) and as many 5 GHz ones as you can, since you have many more non-overlapping channels to work with. Chances are that anyone stuck on 2.4 GHz is going to hate life. Plan power levels as well, and don't run radios hotter than they need to be, despite the temptation.
Also, very, very important: DISABLE LOW DATA RATES. Mandate 5 or 11 Mbps as the lowest supported rate at all the radios. Otherwise the 1 Mbps Nintendo DS's and phones will eat up all the airtime and starve everyone of access. If you can get away with turning off 802.11b support and only offering 802.11g on 2.4 GHz, do so.
Finally, ignore any comment suggesting consumer gear.
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We (citylink.co.nz) provided the wireless (the AP's, not the DHCP and routing) for the recent LinuxConf AU conference in Wellington, NZ. There were something like 700 attendees, and you can guarantee every one of them had at least one wireless device.
We used the Xirrus devices and apart from a couple initial teething issues I believe they coped well with the load.
I think we were using the big 8 radios in a single flying saucer like device, and we used multiple units.
We have used the Mikrotik AP's in the pas
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/
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I have to second the Meraki, I've worked with them a little and they are stupid simple to setup and maintain. From a price perspective they kill Cisco and a lot of the other big vendors as well so it can be a big win all around.
airport extreme (Score:5, Funny)
If you want fall-down easy to setup and manage, they'll get the job done. If you want granular control, don't waste your time. I got sick of trying to make dd-wrt work with WAP, wireless-n and g at the same time a year ago, and just bit the bullet on the apple units. I can say it's been one purchase I don't regret.
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Hey, move your elbow! (Score:2)
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.
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AC knows his stuff. Pay attention. (I have no mod points today. :( )
+1 on renting an expert and equipment to help assure the event is a success, and not a headache because nobody can get online.
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I'd say this is the best answer so far. To be a bit more precise - it really depends on how many people and how reliable you want to be.
A professional event (well paid) should definitely consider getting a real setup - you can rent the equipment and get a setup as part of the deal.
However, if this is a less formal event (e.g. free or near free), then you could probably get by with 3-4 good AP's, some directional antennas, turn the power down, and spread the channels out. Good luck!
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.
Baseball bat (Score:2)
Baseball bats work quite well against one or two. Any more waps than that, you'll need to look for an alternative.
HP/Colubris (Score:2, Interesting)
HP ProCurve has dual radio products from their buyout of Colubris... check out the MSM422. You can run 2-3 of these @ low to mid power with one radio on N (@ 5ghz) and one on b/g (channelized). That should split the traffic up a bit (most newer laptops have 802.11n cards) You should be able to get 200+ users per AP as long as no one tries to connect from the parking lot (hence the low power).
You can also use some narrow-field sector antennas and "columnize" your signals across a room.
If it is a more pe
My Pick (Score:2, Informative)
the best type of setup for that sort of thing... (Score:2)
the best solution is to set up a lot of APs with very very low power and low gain antennas all over the room, in bridge mode, all with the same frequency and SSID, all connected to the same lan, and sprinkle them all around the room.
I've had very good results with Ubiquity picostation 2 attached to the chairs in a keynote style setup (one stage and plenty of chairs...
as for how it works, easy...
the "low power" part, takes care of there being a lot of people. laptop will connect to the closest ap (aka best r
turn of 802.11b!!!!! (Score:2, Interesting)
I addition to my other comments...
Turn off 802.11b. Very few devices still use it but if you enable it the backwards compatibility mechanisms will slow the network to a crawl. It is usually done by disabling the speeds 1, 2, 5.5 and 11Mb/s.
In such close proximity and no signal strength issues i would also recommend making sure you add higher basic rates ( i have no idea what vendors other than cisco call it) as if everyone is connecting faster (whether or not there is more throughput is irrelevant) then t
Linksys routers with simultaneous dual band (Score:2)
http://www.linksysbycisco.com/US/en/products/WRT610N [linksysbycisco.com]
It should be less than $160 and will probably give you the best performance when using N. Never tried it though.
Aruba (Score:3, Interesting)
offer good old Ethernet as well? (Score:2)
other ideas (Score:2)
1. Push everything into 5.8 range you can. Whereas 2.4 (b/g/cheap N) only has 3-4 non-contiguous channels, 5.8 (A/N) has dozens of fully non-shared channels available which should make spectrum contention less of an issue in this band.
2. depending on the geographical area required, back the power levels down using either commercial gear that allows it by default or using one of the freeware (DDWRT/Tomato) firmwares so that it doesn't exacerbate cross AP contention in B/G ranges
3. Directional antennas
4.
Wrong kind of hardware (Score:2)
in your situation i would suggest getting a Bulk reel of Cat6, fittings, PROPER CRIMPERS and then a bunch of that wire channel stuff and then some rack type routers
(hint folks i did say crimpers as in more than one)
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
Meraki and dense deployments (Score:2)
Hey everyone. I'm a software engineer at Meraki (mentioned earlier in the thread by dotwaffle) and wanted to chime in and offer what I can. Our gear is commonly used at conferences, including the most recent LeWeb, a conference in Paris with about 2,000 attendees and VERY heavy WiFi use (social media types that are tweeting, blogging, posting photos and accessing WiFi from their cell phones and laptops). We covered a 12,000 square foot room and other areas without any downtime or customer complaints. This w
Re:WAP? (Score:5, Informative)
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Bad attempt at a funny. But if you have to explain...
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I knew it was a joke! :)
However your joke pointed out that some people might now know what WAP stands for in this context, so I thought I would just put out the definition for those that might not know.
- James
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Fair enough then, happy to hear I didn't have to resort to a smiley!
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:)
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Use ALL 14 WIFI channels ! (Score:4, Interesting)
I have read very good recommendations of having cells of WIFI routers giving 1,4,7,11 in one, 2,5,8,12 in another and 3,6,9 in the third, why lock yourself in?
In Japan, you can use all the 14 WIFI channels, and if your event is the ONE TIME thingy, use all 14 channels !
Do a 1,5,9,13 on router A, then 2,6,10,14 on router B, then 3,7,11 on router C and 4,8,12 on router D on group them into one cell.
Try push all the users of router C and D to 5 GHz band, router B to 3.6 GHz band and router A to 2.4 GHz band.
Use directional antennas, aim router A to North, router B to East, router C to South and router D to West.
Then set up cells within the premise.
In that way the signals that overlaps are not of the same channel, and not in the same frequency band either.
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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
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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]
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Due to the bandwidth, narrow beam antennas will go a long way in partioning the space into sectors for frequency re-use, much like cell phones. See if you can partition your space into cells.
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While using directional antennas will help to some extent, keep in mind that your clients will NOT have directional antennas, and will interfere with each other. A larger number of access points with lower power will help to some extent, but with this many people using the service concurrently, you may have a problem, regardless of how you do it. Also, make sure you don't use a single /24 subnet for client addresses if you have more than 500 clients; you'll run out of address space.
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that is only when ubiquity clients are used, not ordinary 802.11n cards.
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Hey there... I have a vaguely similar project (a campground, more spread out users and outside, and I plan to use ChilliSpot in UAM from a dedicated Chilli/Radius/Squid backend server) coming up in a few months, and I see a lot of people swearing by Ubiqiti (particularly their Rockets), and certainly can't complain abou
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Really these things are just computers that control radios. You're right, all their products can operate as APs, Bridges or Stations. There's a few differences in what the A/B/G products can do vs the M series (AirMAX/MIMO) but they can all operate in any main mode. You should expect that from any vendor.
At lea
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True, and I'll credit them as giving more detailed product info than many companies - Except sometimes that information really doesn't help without knowing their baseline performance (ie, to me as a potential new customer). You mention radio power and CPU/memory, which I can see clearly on their spec sheets - But that doesn't really translate readily into "if you have LOS
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