Please stop asking for an 802.11ac site survey

You are likely reading this post at the recommendation of someone. You have likely asked something along the lines of ‘Will you do an 802.11ac site survey for me?”. This is an easy mistake to make, and I hope that this clarifies a few things for you. First and most importantly, any site survey should always start with the customer requirements, then you position the technology to fit those requirements. If you ask me for an 802.11ac survey, this means that you want a deployment that supports 802.11ac modulation. Modulation occurs at most areas of your cell and as you get further away from your Access Point, your speed decreases, but this does not mean that you don’t ‘get an 802.11ac data rates’. The 802.11ac specification allows for as low as 6.5Mb/s and as high as ‘gigabit wifi’ and all sorts of speeds in-between. With 802.11b/g/n it was possible to ask for ‘the best, and make it pervasive’ and you could theoretically design an environment to support the highest supported data rates in all locations. With 802.11ac, this is no longer possible due to the very strong signal strengths required and the very wide channels required to achieve ‘max throughput’. It is unreasonable to expect an enterprise wireless deployment to support 1300Mbps (or whatever your Access Points spec sheet claims as the max) in all locations for all clients.

If you ask for an 802.11ac site survey without any other clarifications, you can safely expect massive cell sizes and generally poor throughput which is likely not what you want. Examining your Access Points data sheet will give you some idea of the wide range of signal strengths required (not to mention channel widths) to support a variety of 802.11ac data rates. The Cisco AP3700 data sheet for example, shows that -61dBm is required to support VHT80, MCS 9, 3 spatial streams (the ‘highest 802.11ac’ supported on the Access Point at 1300Mbps) all the way down to -92dBm for VHT20, MCS 0, 1 spatial stream (the ‘lowest 802.11ac’ supported on the Access Point at 6.5Mbps). All of these qualify as ‘supporting 802.11ac’. This wide swing in capabilities is the reason that you cannot simply ask for ‘an 802.11ac site survey’. Instead, you should always start by gathering your requirements upfront:

  • What are my throughput requirements?*
  • What are my density requirements?*
  • What are my client types?*

Then turn those expectations into leveraging a technology for the deployment. If you do not set those expectations upfront, or have a good understanding of what your clients requirements are, how can you claim success? You need to mutually agree upon design requirements, then prove that design back in whatever fashion you agree on. Set expectations, design for those expectations, meet those expectations, then prove that you’ve met those expectations. And please, stop asking for an 802.11ac site survey.

* There are many things that go into a proper RF design, not to mention supporting other applications such as BYOD technologies that I’m intentionally glossing over. This is just a small sampling of some of the questions you can use to suss out your customer requirements and is by no means the only way of doing it.

Aruba just doesn’t get Investment Protection

This week, Cisco launched their modular 802.11ac Access Point, the AP3700. The FUD that started almost instantly was unbelievable. This petulant mud slinging is coming from from none other than our good buddies over at Aruba who are trying with all their might to convince all of their AP134/135 users to go buy a new Access Point. While this rip-and-replace mindset has boosted their volume sales over the past several years, I think it’s time that we all revisit what modularity means and why it’s good. We’ll get this bit out of the way first however since it seems to be a common misconception about modularity: Modularity is not only about 802.11ac, it is about investment protection. Aruba wants to spin this to convince you that you a) need to buy a new AP and b) while you’re at it, let’s try and sell you a controller! This slight of hand and misdirection is really in poor form and we should all take a moment to bring this conversation back to the real world. The 802.11ac wave 1 module is one of 4 modules, and one of two Cisco 802.11ac platforms to select from. No one is forcing you to purchase a module to get 802.11ac. Cisco has a ‘rip and replace’ option as well. If you’re okay with the rip and replace approach to 802.11ac (as an Aruba customer you should be used to this by now), by all means – let’s compare a head to head AP3700 against the AP-225 (I’d do this, but for some reason they’re reluctant to send me an AP-220) using clients that are available in a the real world today. By the way, wasn’t it Aruba just a few months back complaining about Cisco using Miercom and proving that the 5760 beats the stuffing out of the 7240 controller and that the AP3600 whomped all over the AP134/135?

Let’s recap the FUD: When the AP3600 was announced, Aruba predicted:

  • That modularity doesn’t work: FALSE – Modularity does work, and has worked since the Cisco 1220 (802.11b to 802.11g migration).
  • That Cisco won’t ship modules ever: FALSE – Cisco has shipped two modules and is on track to ship an additional two.
  • You’re better off buying a new AP: FALSE – well, maybe not false. If you’re an Aruba customer, you have no choice.

This last one is really the sticking point. Most of the customers I talk to can’t stomach a new AP upgrade every year. They’re more along the lines of 3 to 5 year refresh cycles. Realistically speaking, if my upgrade cycle hit last year I could have done one of two things:

  1. Purchased Aruba AP134/135s. This means that I cannot get any sort of 802.11ac without ripping and replacing.
  2. Purchased Cisco 3602s. This means that if I need it, I can deploy 802.11ac (wave 1 or wave 2!), monitor mode, or indoor cell DAS modules at a fraction of the price of a new AP.

At the end of the day, modularity is not intended to be a one size fits all approach to technology. It’s right for some people, it’s not right for others. When it comes down to it, you can either buy more Access Points, or less Access Points, and still get current technology. If you’re considering the Aruba platform today, I’d encourage you to ask the following questions:

  • What do I do with last years APs?
  • How do I get to 802.11ac wave 2 when it comes out?
  • How do I deploy indoor cell DAS leveraging my existing APs?
  • How do I do wIPS without buying a whole new overlay solution?
  • Why aren’t you comparing against the AP3700?

In the meantime, let’s keep Aruba pointed in the right direction shall we? The modular platform argument is one that Cisco battles time and again – look at all of the people that used to hate on the Catalyst 6k platform? They had nothing to compare so, certainly modularity was bad! Modular is good, investment protection is fiscally responsible, and flexibility means that I can get some of todays technology where I need it, when I need it without breaking the bank on forklifting my infrastructure. By the way, let’s do a speeds and feeds with an AP220 and an AP3700 and see how those bar charts look…

In short, it doesn’t matter who’s infrastructure gear you’re buying. Moore’s law means that there will always be a pie chart or bar graph trying to convince you to buy something shiny and new. Modularity is about getting some of that shiny new, without having to forklift your gear – investment protection.

First look: Cisco 802.11ac module for the AP3600

Last year Cisco launched their 3rd modular Access Point, the 3602 featuring 3 Spatial Stream 802.11n, dual radios, and CleanAir support. One of the much touted features was the introduction of a ‘future-use’ modular slot across the back of the Access Point (now called Adaptive Radio Modules ). This was to future proof your investment and at the time, Cisco took a lot of heat for this modular future proof approach to investment protection. Sometime after the Access Point was launched, Cisco announced that there would be at least two modules available, one being the WSSI module (for full time monitoring of off channel events) and the 802.11ac module (to support the yet-to-be ratified 802.11ac standard). I’ve gotten my hands on an 802.11ac module and here is what I know:

a) It’s easy to install:

With two thumb screws on the module itself, you simply grab the AP off of the ceiling tile, unplug the ethernet cable, flip it over, remove a piece of tape to expose the connector, place the module on the back, screw down the thumb screws, re-attach the network cable, and rehang the AP.

802.11ac module

802.11ac module

802.11ac module installed

802.11ac module installed

b) It can require up to 20 Watts*:

#show power inline gigabitEthernet 0/2
Interface Admin  Oper       Power   Device              Class Max
--------- ------ ---------- ------- ------------------- ----- ----
Gi0/2     auto   on         20.0    AIR-CAP3602I-A-K9   4     30.0 

Interface  AdminPowerMax   AdminConsumption    
             (Watts)           (Watts)           
---------- --------------- --------------------  

Gi0/2                 30.0                 30.0
#show power inline gigabitEthernet 0/2 detail 
 Interface: Gi0/2
 Inline Power Mode: auto
 Operational status: on
 Device Detected: no
 Device Type: cisco AIR-CAP3602I-
 IEEE Class: 4
 Discovery mechanism used/configured: Unknown
 Police: off

 Power Allocated 
 Admin Value: 30.0
 Power drawn from the source: 20.0
 Power available to the device: 20.0

 Actual consumption
 Measured at the port: 8.6
 Maximum Power drawn by the device since powered on: 10.2

 Absent Counter: 0
 Over Current Counter: 0
 Short Current Counter: 0
 Invalid Signature Counter: 0
 Power Denied Counter: 0

 Power Negotiation Used: CDP
 LLDP Power Negotiation --Sent to PD--      --Rcvd from PD--
   Power Type:          -                    -
   Power Source:        -                    -
   Power Priority:      -                    -
   Requested Power(W):  -                    -
   Allocated Power(W):  -                    -

c) It ‘just works’:

The 802.11ac module shows up as you’d expect – as a ‘slot 2 radio’ and you can Admin Enable and Disable it. Aside from that, it takes all of it’s RF specific configuration from it’s parent radio – operating in tandem with the integrated 5GHz radio that services your 5GHz 802.11n clients. As with all hardware updates, you’ll need to update your WLC code to a version that supports the module but this is only mentioned as a ‘well duh’ requirement. 🙂

Since the module is adding a radio specifically to support 802.11ac clients, it increases the total client capacity of the AP3600 to a whopping 450 (200 for 802.11n 2.4GHz, 200 for 802.11n 5GHz, and 50 for 802.11ac)! While the jury is out about it being a good idea to try and support 450 clients on a single AP, the capacity numbers are listed for the inevitable vendor-bashing that is sure to ensue!

d) Clients will be the next big challenge:

As with the transition from 802.11b to 802.11g, then to 802.11n, the transition to 802.11ac will derive most of it’s pain from client adapters. Driver updates, marginal modulation benefits at distance, etc. The biggest benefit from 802.11ac will be the cleaner frequency requirement (5GHz) but poor roaming choices from clients will most certainly be the biggest pain point we all grapple with.




*Does the module require more than 15.4W PoE?

No! The module can be operated at *full* 802.11ac performance in class 3 power by disabling the 2.4GHz radio on the AP. This is the only solution on the market that offers *full* 802.11ac performance in Class 3 power. This means that you can deploy 802.11ac today even without switch upgrades! Here is a show power from a AP and module servicing 802.11ac clients:

#show power inline gi0/2
Interface Admin  Oper       Power   Device              Class Max
--------- ------ ---------- ------- ------------------- ----- ----
Gi0/2     static on         15.4    AIR-CAP3602I-A-K9   4     15.4 

Interface  AdminPowerMax   AdminConsumption    
             (Watts)           (Watts)           
---------- --------------- --------------------  

Gi0/2                 15.4                 15.4

Is this Cisco’s 802.11ac Access Point?

No! This is a 3 spatial stream 802.11n Access Point with an 802.11ac module. While I cannot comment on future or unannounced products, it stands to reason that Cisco will continue to evolve products and announce those products when they’re ready. It’s my opinion that a fully fledged 802.11ac Access Point will be announced at some point.

Can you tell me more about a dedicated 802.11ac Access Point from Cisco?

No. I have no disclosable information on an 802.11ac Access Point from Cisco.

How much does the module cost?

The list price for the module is around $500. Engage your Cisco Account Manager and Partner team for your discounted pricing (and don’t pay list). 🙂

What other modules are there for the AP3600?

There is a small cell 3G module available.

Will there be future modular Access Points from Cisco that support these modules?

I have no disclosable information on an unannounced products from Cisco.

Is this the end? What about speeds and feeds? What about a take apart so we can see what’s inside?

There will be a followup post. What would you like to see?