What is a suitable AP for a high density location?

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A1den

8 posts

Wannabe Geek

#177150 23-Jul-2015 21:42

I am currently working in a large project where BYOD and contractor internet access is provided over a basic Spark business broadband plan and uses Spark's default Huawei HG659b modem. Unfortunately this modem/router cannot handle ~30-40 concurrent users connecting for the course of a work day and as result kicks many from the network and has overall very bad performance.

I have been tasked to find a replacement modem and access points to solve the problem. I was thinking of keeping the existing modem, disabling WIFi access and installing two Ubituiti access points from PB Tech at each end of the large room.

Do you think this solution would be adequate or is a different configuration needed?

ubergeeknz

3344 posts

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Vocus

#1350828 23-Jul-2015 21:46

Any reason you can't provide wired access? I'd still put in a better AP, but if you provide wired access for those who can make use of it, you will take a lot of load off.

Sideface

9353 posts

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#1350831 23-Jul-2015 21:50

What is your "basic Spark business broadband plan"?
With 30-40 users, it may be more than a wireless problem.

Sideface

sbiddle

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Biddle Corp

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#1350835 23-Jul-2015 21:56

The first step before even thinking about APs is to look at the router and connection. If you're on ADSL2+ you're not going to be able to handle that many users, and I'd be very surprised if the NAT table on such a device could handle 40+ concurrent IPs either.

Zeon

3916 posts

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#1350877 24-Jul-2015 00:08

Definitely look at a faster connection like VDSL or UFB. What is that new Ubitiuiti router like? You could go all ubiquiti if you got their router and UniFi access points...? Have a look at Gowifi.

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Aredwood

3885 posts

Uber Geek

#1350890 24-Jul-2015 00:55

Also have a look at the DHCP lease times and IP pool size. As if the lease time is 1 week, and the pool size is 128. Then if you have more than 128 unique computers / devices connecting over the course of a week. You will run out of IP addresses. Devices will still be able to connect but won't get internet access.

The Ubiquity edge router will definitely suit this situation. As the latest firmware supports FQ_codel. Which allows you to saturate the upstream without ping spikes or major packet loss. Which will be very important if the connection is ADSL or something else with a low upload speed. As currently if 1 device starts syncing photos to dropbox or iCloud ect. It will saturate the ADSL upload. And then the net will slow right down for every other device.

pdath

252 posts

Ultimate Geek

#1350906 24-Jul-2015 07:52

WARNING: I work with and love Cisco products.

A perfect solution for something like this is a Cisco Wireless Lan Controller 2504. Currently their is a promo on where you get the WLC controler and 2 access points for a massive discount. It would be a very reliable solution. You can also easily scale it up.

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chevrolux

4962 posts

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Inactive user

#1350941 24-Jul-2015 08:35

Unifi Pro AP's and a Mikrotik router. Set up some queueing to rate limit wireless users (or maybe just use captive portal for rate limiting) and all will be good. Queuing would allow you to set burst rates though too so those that are well behaved are allowed the odd bit more bandwidth every now and again.

Would definitely look at a better connection though. Vdsl as a minimum.

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BTR

1527 posts

Uber Geek

#1351052 24-Jul-2015 10:31

A Ruckus R710 will support up to 500 users if thats enough :-)

A1den

8 posts

Wannabe Geek

#1351112 24-Jul-2015 12:13

Thanks for the suggestions guys, heaps of good to use info.

@ubergeeknz: Wired access is provided, however WiFi is specifically for contractors and BYOD phone/tablet/laptop use.
@Sideface and sbiddle : Broadband is also being upgraded to UFB/VDSL
@Zeon: Looking now, thanks for the suggestion
@Aredwood: Thanks for the suggestion, I initially looked at modem settings and all checks out. It seems to be a concurrent connected user limit more than anything
@pdath: PMd
@BTR: Cheers, looking now at this option.

1101

3122 posts

Uber Geek

#1351202 24-Jul-2015 15:21

on a related note
just wondering..

just how many simultaneous wifi connections can you reliably have on a single low spec wifi router ?
assuming its running WirelessG , as wifi will drop down from N to G if even a single G device is connected (I assume)

I guess there are 2 issues, wifi bandwidth needed for all the connections & ability for cheap AP's to cope with 20-30 connections & the AP's ability to process the data for 20 -30 connections ?

I have seen a cheap AP have issues with 8 wifi connections (but that was fixed with a firmware update)

pdath

252 posts

Ultimate Geek

#1351206 24-Jul-2015 15:34

That question is impossible to answer with no other information.

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raytaylor

4014 posts

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#1351427 25-Jul-2015 00:31

Collision Collapse:

Wifi is based on CSMA as a method of multiple access - old thinnet and 10mbit LAN networks used the same method.

When a packet is sent between a an AP and client device, an acknowledgement is returned to say the packet is recieved in good order. If the acknowledgement fails, the packet is resent.

When a user streams data, the packets flow nicely between the AP (router) and the client device (ipad / laptop)

When User-2 comes along and tries to send an http get request for www.google.co.nz their device will interrupt the stream of data between the AP and User-1

CSMA kicks in.
The interference from User-2 causes the packet traveling between User1 and the AP to be malformed. The acknowledgement fails.
Both devices therefore go through a process of

1) Both devices stop sending data
2) Both devices pick a random amount of time. Hopefully they dont pick the same number.
3) Each device will attempt to resend their packet. If they picked a different time, they will hopefully get their packet through.
4) Each device will continue to send more packets
5) If two packets try to be transmitted at the same time, the process begins again.

When this happens over and over and over again, its called collision collapse.
The total throughput of the AP drops to almost nothing due to all the stopping, waiting and restarting.

Now all wifi routers suffer from this. Even the best.
But some of the fancy ones like the Ruckus can do things to mitigate the damage.

So basically unless you are willing to spend thousands on a centrally managed system, your typical maximum usage through a $100 to $500 wifi router is
30 users doing nothing idle -or-
25 users pinging 8.8.8.8 -or-
18 users lightly surfing trademe -or-
1 user streaming youtube and 1 user trying to lightly surf trademe/

Once you have the wifi sorted, then your next step is to get the broadband fixed.

My suggestion is to simply buy 3 wifi routers, set them all to 20mhz, one on channel 1, another on channel 6, and the third on channel 11.
That way the client devices can be spread over the 3 access points so the collision collapse isnt so bad on each one.
Even if you just get two routers that have an "AP Only Mode" (most belkins do) and just plug those into the ISP provided router.

A school can easily run on a reasonably fast ADSL connection - i doubt your subcontractors are going to be looking at videos so you should be fine there.

Ray Taylor

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webwat

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#1351668 25-Jul-2015 18:24

To improve the congestion you can set a feature called RTS to something like 1024 or whatever works for you. This means that total throughput will be slower but there should be less collisions because the router gives a warning that its "ready to send" any packets over that size. This way you reduce the workload on the AP as well as reducing the number of collisions. Not sure if it would help to share the bandwidth around more fairly.

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jnimmo

1097 posts

Uber Geek

#1351752 25-Jul-2015 22:35

A Meraki MR32 would do very nicely
Also has the benefit of being cloud managed, you can easily see online who is using what traffic and rate limit if needed

EDIT: And probably a more solid router - although I think you could use the Meraki as the NAT router and just bridge the ADSL modem through to it