Tuesday, November 26, 2013

802.11 AC and the Cisco AC Module for 3600 Access Points

Hi Guys

This blog post is about the Cisco 3600 access point, the 802.11 AC Module (wave 1) available for that access point and finally the software called "chanalyzer" available to help you with detecting interference and leveraging your Cisco Cleanair access points.

So Incase you where not aware, Cisco have had some access points out now for quite some time called the Cisco 3600 Access Points:

The picture above shows them in all there glory, along with the 802.11 AC Module.

The 802.11 AC module is I believe, an industry first in that your existing 802.11N access points (the 3600's) can be field upgraded to 802.11AC.

The module simply plugs into the back of the AP, as shown in the following pictures:

As you can see, it's quite straight forward! Simply place the module into the slot shown on the AP and then tighten the finger-tight screws

- If 802.11 Ac can offer "gigabit wifi", and its maximum theoretical speed is 1.3 Gigabits per second, don't I need more than 1 gigabit connection from the AP to the switch?

No! 1.3 Gigabit is the maximum theoretical PHYSICAL speed of the radio media, the actual throughput onto the LAN will be less, quite a bit less as we will see.

- Does the 802.11 AC Module require more power?

Yes, you need to make sure your switch supports POE+, the output below shows the wattage required for a 1142 vs the 3602 with the 802.11 AC Module:

homeSwitch3750#show power inline

Module   Available     Used     Remaining
          (Watts)     (Watts)    (Watts)
------   ---------   --------   ---------
1           480.0       35.4       444.6
Interface Admin  Oper       Power   Device              Class Max
--------- ------ ---------- ------- ------------------- ----- ----
Gi1/0/5   auto   on         20.0    AIR-CAP3602I-N-K9   4     30.0
Gi1/0/18  auto   on         15.4    AIR-LAP1142N-N-K9   3     30.0

- Is it really just plug and play?

Yes! Simply turn the AP off, plug the module in, turn it back on and make sure your running WLC Code of version 7.5 or later, then enable 802.11 AC in the controller.

What kind of speed can we really get from 802.11AC?

I tested with the following equipment:

ASUS PCE-66 802.11 AC Wireless Card
Windows 7
Cisco 3600 Access Point
 Laptop connected to gigabit network.

The enviroment was a home setup with quite a bit of wireless interference.

The first step was to establish a gigabit ethernet (wired) benchmark, which resulted in:

722 Megabits per second

The following tests where undertaken:

802.11AC (5.0ghz only, 80 Mhz)
5.0Ghz, TCP, Close Average Speed: 166 Mbits/Sec
5.0Ghz, TCP, 1 Room away Speed:  102 Mbits/Sec

As you can see, it's not even in the same ballpark as what we can get for wired, but it's a significant improvement over 802.11N:

802.11n (5.0Ghz. 40MHZ)
5.0 GHZ TCP Close average speed: 108 Mbits per Second
5.0 GHZ TCP, 1 Room Away Speed: 69.3 Mbits Per Second

802.11n (2.4 GHZ)
2.4 GHZ TCP, Close Average Speed: 71.1 Mbits Per Second
2.4 GHZ, TCP, 1 Room Away Speed:, 50.1 Mbits Per Second

The results above show that 802.11 AC could potentially be a worthwhile improvement, but is certainly not the gigabit wifi we have been led to believe it could be.

The speeds, as rough as they are closely match those achieved by Tom's Hardware:


I discovered Chanalyzer at a customers site and wanted to share it with you guys, it' s an exceptionally useful tool when combined with Cisco Clean Air


The software can be used to connect to a Cisco Access Point running clean air to retrieve spectrum information in real-time!

The above screen looks quite busy but is essentially showing interfering  devices, in this case an xbox controller. This real-time analysis can really help you realize what might be affecting the network.

After dowloading Chanalyzer, you will need to connect to the AP:

The NSI key stands for "network spectrum interface key" and can be found on the WLC Access point page:

This can be very useful for troubleshooting Clean Air Problems.

I hope you enjoyed this blog!

Incidentally, this is my first blog post as a Cisco Data Center Champion, an honor I was recently bestowed by Cisco. Hopefully I can live up to the name!


  1. Hi Pete,
    Near Gigabit speeds are coming, but your talking about Phase 2 stuff. (160MHZ channels and different modulation schemes)
    Here's a good reference:

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