Musings on Multigigabit and APeX

Cisco Live is always a whirlwind of information and the 2017 US event was no exception! Between the Catalyst 9k launch, the focus on Software Defined Access, and Intuitive Networking, it’s easy to miss some of the nuance that was to be uncovered on the show floor. In the Enterprise Networking booth there was a hidden nugget that was focused on developers called APeX (short for Access Point Extensions). One part of this APeX program is the Extender Module Hardware Development Kit – EM-HDK for short (or just HDK for even shorter!) that plugs directly into the often-overlooked module port on the AP3800. The board itself is a neat springboard for developing on – it allows you to attach a Raspberry Pi, Arduino, XBee or other Small Board Computer directly to the AP. Of course, you wouldn’t deploy a production solution like this, but you would take the solution you’re working on, and compress it to a design that’s purpose built for the modular slot that’s part of the AP3800.

Or HDK for short.

The APeX EM-HDK

The thing that struck me though is that while the HDK is neat – and if you have any SBC experience at all, a very interesting platform, the hidden secret of the HDK is that it also sports two Gigabit Ethernet connections supporting PoE out. It is worth noting that if your host AP had a single 1 Gigabit link, and you put two additional 1 Gigabit links on the back side of it, you can safely assume you have an automatic bottleneck. This is the genesis of my epiphany – those that were shortsighted enough to make claims that 802.11ac wave 2 doesn’t justify uplink speeds beyond 1 Gigabit, clearly did not take into account that 2x 802.11ac wave 2 radios moves you a lot closer to that 1 Gigabit bottleneck, and when you want to pass an additional 2x 1 Gigabit Ethernet interfaces on the same link as your 2x 802.11ac wave 2 radios, your use case for Multigigabit becomes pretty clear.

HDK with Raspberry Pi attached to an AP3802i.

Remember folks, your wired infrastructure is expected to last much longer than your typical switches will. As you start seeing very obvious use cases for breaking the 1 Gigabit uplink requirement, make sure you’re considering the cost savings of investing in multi gig technology today – especially if you can get it for a nominal uptick in price.

Multigigabit!

Multigigabit interfaces, left. 10G, right.

Go here for more information on Cisco’s mgig (or NBASE-T) and here for information on the APeX program over at Devnet.

Cisco Wave2 site survey how-to

So, you have a shiny new Cisco 802.11ac wave 2 Access Point and you went to go grab the autonomous code for it to do an APoS survey – but then realized there isn’t autonomous code for the 2802 or 3802 (or any other wave 2) Cisco AP, huh? You may have noticed that there is a new product called Mobility Express. You can use this ‘controller on an AP’. Here is a guide I co-authored for doing just this.

-Sam

Summary:

Cisco 802.11ac Wave 2 APs do not run IOS like previous platforms. This presents a challenge when trying to perform an AP on a Stick site survey with only a battery pack. The standalone mode for these Access Points is achieved using Mobility Express – or the function to use the integrated WLC on the Access Point to control the radio functionality in a standalone fashion.

Prerequisites:

  • 8.3MR1 code supporting Mobility Express for your Access Point
  • Local power source for your Access Point (AIR-PWR-C or site survey battery with sufficient power)
  • Operational Standalone or Virtual Wireless Lan Controller running 8.2MR2 or 8.3 for configuring the Access Point mode and moving the images
  • TFTP server
  • 802.11ac Wave 2 Access Point (Please note, the 1810 platform is not supported at the time of this writing)
  • A serial console cable to watch/configure your AP

Process:

Step 1) Join your Access Point to your local WLC as you would during a normal deployment.

For the 2800/3800 platforms, you must be running a minimum of 8.2MR2 or 8.3 for step 1. For 1830/1850, there is no similar requirement aside from running a release that supports those platforms. Please note that this is not the above referenced ME image version which will be used in step 2.

Step 2) Convert the Access Point to Mobility Express mode using the correct image.

This is accomplished by going to the console of the AP and logging in, then enabling, then using the ap-type command to convert the AP over to Mobility Express and download the new image from your TFTP server. To get the correct AP image file, you will need to decompress the image bundle and use the correct image for your AP platform. For example:

  • 1830/1850 you should use ap1g4
  • 2800/3800 you should use ap3g3

Note: You can also use the platform specific ME image from CCO if you have that available. If you’re using a Universal SKU AP, you should wait for it to regulatory prime before trying to convert the image to make sure you don’t incur a reboot mid-code change.

Once your AP goes down for a reboot, disconnect the LAN cable and ensure its powered by local power or your survey battery pack:

Step 3) Wait for your Access Point to boot completely.

At this point your Access Point will do several things. It will boot and you will see about 2 minutes of the following messages:

Once these timeout, the Access Point will boot the Mobility Express WLC automatically:

Step 4) Configure the WLC using the following values:

Would you like to terminate autoinstall? [yes]: yes
Enter Administrative User Name (24 characters max): admin
Enter Administrative Password (3 to 24 characters): Cisco123
Re-enter Administrative Password : Cisco123
System Name [Cisco_11:aa:1a] (31 characters max): ME_WLC
Enter Country Code list (enter ‘help’ for a list of countries) [US]: US
Configure a NTP server now? [YES][no]: no
Configure the system time now? [YES][no]: yes
Enter the date in MM/DD/YY format: <date>
Enter the time in HH:MM:SS format: <time>
Enter timezone location index (enter ‘help’ for a list of timezones): 7
Management Interface IP Address: 192.168.1.2
Management Interface Netmask: 255.255.255.0
Management Interface Default Router: 192.168.1.1
Create Management DHCP Scope? [yes][NO]: yes
DHCP Network : 192.168.1.0
DHCP Netmask : 255.255.255.0
Router IP: 192.168.1.1
Start DHCP IP address: 192.168.1.10
Stop DHCP IP address: 192.168.1.200
DomainName : me.local
DNS Server : [OPENDNS][user DNS] OPENDNS
Create Employee Network? [YES][no]: yes
Employee Network Name (SSID)?: survey_ME
NOTE, USE YOUR INITIALS INSTEAD OF ‘ME’ TO DIFFERENTIATE YOUR SSID
Employee VLAN Identifier? [MGMT][1-4095]: MGMT
Employee Network Security? [PSK][enterprise]: PSK
Employee PSK Passphrase (8-38 characters)?: <temp key>
Re-enter Employee PSK Passphrase: <temp key>
Create Guest Network? [yes][NO]: no
Enable RF Parameter Optimization? [YES][no]: no
Configuration correct? If yes, system will save it and reset. [yes][NO]: yes

It is highly recommended to use the values above. Once the Access Point reboots continue on.

Step 5) Clean up the AP

Some of the defaults are not completely friendly. We’ll clean those up now. Discover the name of the Access Point using ‘show ap summary’ and rename it to something more friendly like ‘ap’. It should be noted that renaming your Access Point to ‘ap’ will make configurations easier and in line with the examples below, but if you’re part of a larger team and require unique Access Point names, this is where you would set them, making note to use your defined Access Point name instead of the shortened name ‘ap’ as described in the rest of this document.

Next we want to disable the PSK security on the WLAN for easier association and testing and enable Aironet Extensions to include the AP name in beacons. This step is optional, but recommended. You must first disable the WLAN, the disable the PSK, then re-enable the WLAN:

(Cisco Controller) >config wlan disable 1
(Cisco Controller) >config wlan security wpa disable 1
(Cisco Controller) >config wlan ccx aironetIeSupport enable 1
(Cisco Controller) >config wlan enable 1
(Cisco Controller) >save config
Are you sure you want to save? (y/n) y

Once you’ve made these changes, perform a ‘save config’ as shown on the WLC to ensure the changes aren’t overwritten.

Step 6) Configure your radios for site survey specifics including channel and TX power.

To set these values, you must admin disable the radio, make the change, then re-enable it. Remember, these are the same commands you’d use on a production, bare-metal WLC and are not new. Here are a few examples:

To change the 2.4GHz radio to channel 6:
(Cisco Controller) >config 802.11b disable ap
(Cisco Controller) >config 802.11b channel ap ap 6
(Cisco Controller) >config 802.11b enable ap

To change the 2.4GHz radio to power level 3:
(Cisco Controller) >config 802.11b disable ap
(Cisco Controller) >config 802.11b txPower ap ap 3
(Cisco Controller) >config 802.11b enable ap

To change the 5GHz radio to channel 44:
(Cisco Controller) >config 802.11a disable ap
(Cisco Controller) >config 802.11a channel ap ap 44
(Cisco Controller) >config 802.11a enable ap

To change the 5GHz radio to power level 5:
(Cisco Controller) >config 802.11a disable ap
(Cisco Controller) >config 802.11a txpower ap ap 5
(Cisco Controller) >config 802.11a enable ap

To change the 5GHz radio width to 40MHz:
(Cisco Controller) >config 802.11a disable ap
(Cisco Controller) >config 802.11a chan_width ap 40
(Cisco Controller) >config 802.11a enable ap

Of course, you can couple all of these commands together to reduce the number of times you’re disabling your radio if you’re doing an initial configuration. Here is an example of setting the radios both to power level 2 and the 2.4GHz radio to channel 11, and the 5GHz channel to 100@40MHz all in one script:

(Cisco Controller) >config 802.11b disable ap
(Cisco Controller) >config 802.11a disable ap
(Cisco Controller) >config 802.11b channel ap ap 11
(Cisco Controller) >config 802.11b txPower ap ap 2
(Cisco Controller) >config 802.11a channel ap ap 100
(Cisco Controller) >config 802.11a txpower ap ap 2
(Cisco Controller) >config 802.11a chan_width ap 40
(Cisco Controller) >config 802.11b enable ap
(Cisco Controller) >config 802.11a enable ap

To see the channel of the Access Point currently configured, use the ‘show ap channel ap’ command:

To see the power level of the Access Point currently configured, use the ‘show ap config slot 0 ap’ (for 2.4GHz) or ‘show ap config slot 1 ap’ (for 5GHz’ command and look for the following data:

Alternatively, use the grep command to just pick out the data you’re interested in:

Step 7) Alternative management via the WLC GUI

If you’ve followed this guide up till now, you can also access the management interface of the WLC by using your PC and joining your open survey SSID. Then open a web browser and navigate to https://192.168.1.2/ .

Step 8) Putting it all back the way you found it

To convert the AP back to capwap mode and undo this configuration, you must goto the AP console using ‘apciscoshell’ and perform the ‘ap-type’ command again:

Addendum:

Dual role radio notes:

The AP2800 and AP3800 both include the ability to change the slot 0 radios personality from 2.4GHz to 5GHz. This presents some unique configuration considerations as follows:

To convert the XOR radio from the default 2.4GHz to 5GHz and change its channel to 40 @ 40MHz wide use:
(Cisco Controller) >config 802.11-abgn disable ap
(Cisco Controller) >config 802.11-abgn role ap manual client-serving
(Cisco Controller) >config 802.11-abgn band ap ap 5GHz
(Cisco Controller) >config 802.11-abgn channel ap ap 40
(Cisco Controller) >config 802.11-abgn chan_width ap 40
(Cisco Controller) >config 802.11-abgn enable ap

The following should be noted for this configuration:

When you convert the XOR radio into 5GHz mode, you must use a channel that is 100MHz apart from the slot 1 radio in the Access Point. When you configure the XOR radio into 5GHz mode on an ‘e’ model of AP, you must have an external antenna plugged into the DART connector or this configuration will fail. When you configure the XOR radio into 5GHz mode on an ‘i’ model of AP, the tx power will be fixed and not modifiable (by design) to its lowest possible value to retain micro-cell integrity.

To change the XOR radio from a configured 5GHz to 2.4GHz and change its channel to 6 use:

(Cisco Controller) >config 802.11-abgn disable ap
(Cisco Controller) >config 802.11-abgn band ap ap 2.4GHz
(Cisco Controller) >config 802.11-abgn channel ap ap 6
(Cisco Controller) >config 802.11-abgn enable ap

NETSCOUT AirCheck G2 unleashed!

This blog post is part 1 of a multipart series on the new generation of Wi-Fi tools. There has been a dramatic evolution of the various tools that the WiFi professional uses over the past year or so . I wanted to take a moment and spell out my thoughts on the current state of tools in our industry.

First shown at the Wireless Field Day 1 in San Jose the Fluke AirCheck rapidly became the staple of the ‘serious’ WLAN troubleshooter. It made a huge splash and was immediately lauded for it’s easy straightforward to getting down to the serious data that you need to see when troubleshooting your wireless network. All of the heavy hitters in the industry have been talking about them since then and it’s almost unbelievable that it was just assumed that people would have them on anything but the most entry level of jobs. The platform had very few deficiencies overall and almost became part of the de-facto tool that you would be expected to know and use – almost like site survey software.

The G2

AirCheck G2 – The green is a nice touch!

It’s hard to think of something replacing the Fluke AirCheck but the inevitable has happened. There is and Application & Network Performance Management company called NETSCOUT recently acquired the Fluke team responsible for the AirCheck – which was in the midst of developing the next generation of the product. Launched late last month, the AirCheck G2 promises to best it’s predecessor in several areas. Head on over to the official announcement and keep a keen eye out for a quote or two from yours truly! 🙂

 

IMG_2593

I was fortunate enough to be included early on in the development conversations of the AirCheck G2 and so like to believe that I helped shape in some small way the look, feel, and usability of the product as it exists today. From early on, there was a focus on the ‘gimme’ features such as inclusion of a color touchscreen. Other features didn’t develop till later on such as the built in ethernet port for wired testing in the field. Those of you that love the LinkSprinter functionality, this is aimed squarely at you! In fact, there is a laundry list of features that read like a who’s who of todays troubleshooting gear – 802.11ac support, long life battery, external antenna support, USB expansion ports, on screen keyboard and navigation menus, auto testing, and rapid boot & shutdown, just to name a few.

Note the External Antenna port on the far right (capped) for the directional antenna attachment.

Note the External Antenna port on the far right (capped) for the directional antenna attachment.

By far and away though, the feature that I’m most enamored with at the moment is the Link-Live.com integration. Starting with an easy way to claim the devices online, a one stop shop for getting your software and updates, and of course, upload notifications of the testing you’ve just done – the ability to bring Organizational structure to such an outstanding troubleshooting tool really brings the product full circle. NETSCOUT has done a superb job of rolling functionality and usability into a cloud based product and included it with the product! This wraps up all of the auto-testing into an easy to use and store place for testing and validation. While this may seem like simple functionality, for an organization with multiple units in the field, this sort of automated cloud-rollup functionality is hands down one of the best features of the AirCheck – and that’s saying a lot!

Useful for making sure the link you're using is functional!

Useful for making sure the link you’re using is functional!

If you haven’t had a chance to get your hands on an AirCheck or have been waiting for a refresh to make the product ‘perfect’, now is the time. You should go ask your VAR, NETSCOUT rep, or beg borrow or steal one to get some time under your belt with one. The simplicity of the product, ease of use, intuitive navigation, and ready access to some very in-depth and advanced data in a straightforward way to consume it.

10 reasons to take another look at 2015 Cisco Mobility

Let’s face it, Cisco is huge. They’re massive, and occasionally they get things wrong. If you’ve strayed away from Cisco in the past year (or longer) because of a specific issue or gap, it’s high time you took another look. The Cisco Mobility offerings today are a far cry from what they were just an easy year back. Here are 10 great reasons to go get reacquainted with the 2015 Cisco Mobility offerings:

1) 5520/8540 WLCs

The introduction of a Converged Access 60G solution highlighted the gaps in the WLC portfolio in the 20/40G of throughput range. Both of these new controllers (one 20G, one 40G capable) are based on the more mature AireOS codebase running 8.1 and later. While this doesn’t mark an EOS/EOL announcement for the 5508 (clocking in at 8G), it does give that 7 year old platform some good alternatives for lifecycle management.

2) Prime Infrastructure 2.2 then 3.0

Ever since WCS was taken over and moulded into the NCS then Prime Infrastructure products, it’s always bore the scars of a legacy mired in Adobe Flash performance issues. Couple that with a dramatic uptick in features and you’ve got a recipe for disaster. The new versions of Prime Infrastructure are actually performing as well as they should be starting at about the 2.2 version and the new UI of Prime Infrastructure 3.0 completely moves away from Flash and demonstrates a significant re-think of the product – including ‘Make a wish!’.

3) 802.11ac wave 2

Let’s not forget the fun stuff – APs and radios. With competitively positioned 802.11ac Wave 2 products, Cisco is staying in the lead of the latest and greatest standards. With impressive throughput numbers, multiple gigabit uplinks, and fancy new features like MU-MIMO, the 1830/1850 APs are clearly paving the way for the next generation of some pretty obviously numbered future platforms. The only question is, what does Cisco have in store for us next?

4) HALO

No, not the game – the new Hyper-Location Module and antenna array. Cisco is delivering on the promise that the industry made to us oh so many years ago about leveraging your WiFi network as a platform for tracking your enterprises assets. Touting down to 1 meter accuracy, this module for your AP3600/AP3700s will take your location fidelity ‘to the next level’.

5) Mobility Express

Those that don’t like having a bare metal controller and don’t see the need for controller based features (such as centralized data plane), we now have a ‘controller on the AP’ option! This allows us to focus on the smaller deployments without the extra cost and complexity (such as it is) for those customers. This isn’t a ‘one size fits all’ approach that we’ve seen in the past, but rather an evolution of a well thought out strategy to bring enterprise features to every market segment.

6) UI improvements

Along with the Mobility Express product, the ‘metal WLCs’ are sporting a new user interface and out of the box setup experience (Day 0 and Day 1 support). If you’ve felt the WLC interface was a bit dated in the past, go take a gander at the plethora of new graphs, charts, and actual usable data about your infrastructure – all without having to goto a larger NMS platform!

7) CMX Evolution

The MSE product is finally getting some legs under the advanced location pieces. This easy to deploy ‘for everyone’ product starts to bring some pretty insightful analytics to any sized deployment – all the way down to a ‘no maps required’ presence analytics and all the way up to a Hyperlocation enabled, social media engagement platform. With both on premises and cloud based offerings available, it really is very easy to start getting very insightful data out of any sized network.

8) CCIE Wireless version 3

The dated CCIE (Cisco Certified Internetwork Expert, Wireless) exam has been updated to include software and hardware platforms from this year. You can now tackle one of the industries most challenging certifications on contemporary labs that are actually relevant to solutions you’re deploying today!

9) UX domain APs

See my previous blog on the topic for a more in-depth look at the UX products, but for those buying and deploying APs spanning multiple countries, this is a pretty good way to reduce a ton of deployment and ordering complexities. By standardizing on a single SKU globally, you can make quick work of some of the logistics nightmares of the past.

10) Cisco ONE licensing

Yes, licensing is boring, complicated, and expensive. Cisco ONE addresses all three of those pain points in one easy go. With a ‘count the AP’ approach to licensing, you can now start to take advantage of all of the above products in an easy to consume, deploy, and license fashion – without breaking the bank. For example, if you wanted to replace your old WLC with a new one, in the past, you would end up repurchasing your AP licenses. In this model, all products start at 0 APs and you pick the size that’s right for you – at any scale. Pick the solutions you want to deploy: ISE, Prime Infrastructure, advanced location analytics, etc – and go! A significant departure from the traditional licensing model in Cisco-land.

I know that a ‘recap overview’ blog sometimes seems too lofty, but there really is a ton to see if you’ve been unplugged from the Cisco world over the past year or so. Take a deep breath and plunge back in at any level and you’ll find something new that wasn’t there before. The Cisco ship sometimes turns slowly and sometimes it’s easy to forget that there is innovation happening all over the mobility space in San Jose.

Disclaimer: I was part of the Wireless Field Day 8 delegation to Cisco where we learned about several of the above topics. For more information on Cisco’s appearance at WFD8, go check out the video!

The evolution that will start the revolution

You’ve heard it all before, evolutionary technology versus revolutionary technology. Everyone wants their newest technology to be revolutionary – expecting it to be life changing and a wide-sweeping, compelling reason to spend tons of money. This is rarely the case and more often than not marketing fluff to try and get you onto the next big thing. Occasionally we get such an unassuming technology announcement that fits squarely in the ‘no big deal’ from a speeds and feeds perspective that it’s easy to overlook. This is clearly the case with the recent multigigabit announcements from Cisco during Cisco Live, Milan. Multigigabit is a technology that allows your existing cabling to support speeds in excess of 1G, without having to make the jump all the way to significantly more costly 10G. Since we already have technology that address speeds and feeds above what we’re talking about here (how many 10G uplinks have you deployed recently?), it’s easy to overlook the impact this will bring to our daily lives. The ability to move to 2.5G and 5G link speeds without having to make the jump all the way to 10G will allow us to get improved link speeds without having to pay a premium for them. The expected cost increase is estimated to be anywhere from 0% to 15% according to the rumor mill which makes the 250% to 500% speed bump quite attractive!

802.11ac wave 2
The reason I’m taking about it is the fact that this brings with it the promise of addressing the 1G bottleneck that people have been gnashing their teeth over in the wireless space for the past couple of years. While we’ve been able to reasonably deflect the speeds and feeds conversation with 802.11ac wave 1 (speeds approaching 1G wired requirements), there has been no good way to move past that without having a two-cable conversation. The assumption up till now has been that 2x 1G links will be the way forward and many people have been running two copper runs out to their Access Points for the past several years in anticipation of this approach. 802.11ac wave 2 will undoubtedly break the 1G barrier in fairly short order with speeds being promised of (best case) 6,930Mbps PHY rate (about 4,900Mbps on the wire). Multigigabit solutions will allow us to address these concerns without having to invest in 10G links. Better yet, it will allow us to address these concerns without having to consume two 1G ports on our switches. Regardless of the solution you choose (1x 10G or 2x 1G), the cost for deploying a single Multigigabit link supporting up to 5G will be less at scale.

Power
The other unassuming byproduct of this conversation is that Access Points require power to bring up all of those components. It will be nearly impossible to power up a 10G ethernet interface in an AP in the power budgets that we have today. By reducing the link speed requirements to 5G, we can save power at the edge device and still fit in modern negotiation. Multigigabit solutions today will provide PoE, PoE+, and UPoE to ensure that the wave 2 APs that we’re going to be hanging will have ample power for whatever they’re going to bring.

The Revolution
I predict that the incremental cost and intermediary speeds will allow us to start having conversations about the jump to 10G. Multigigabit solutions on Access Points, switch uplinks, and desktop and server nics will be the next big thing. Stackable solutions today promise backwards compatibility so you don’t have to rip and replace – just add a stack member and you’re good to go in that closet/IDF! Regardless of your future proofing plans, enabling faster wireless, or just ensuring that you’re not spending money after (can you believe it?) now legacy 1G infrastructure, make sure you’re having a conversation today about ethernet to bridge the gap to 10G.

For more information about the NBASE-T alliance, go here.
For the Cisco Live, Milan – Tech Field Day Extra event with Peter Jones, go here.

Drag racing the bus

Picture it. You’re a school district transportation engineer. You’re in charge of purchasing a fleet of new school busses for your district. The big ones. The expensive ones. The ones that will last you for the foreseeable future. So, you call up Bus Vendor A, B, and C and inform them that you’re in the process of selecting a fleet of new school busses. The following week each vendor dutifully delivers their ‘bus of choice’ to be evaluated. You then grab your intern, put him at the midway point of the bus from ‘Vendor A’ and take it for a spin! You see how fast it goes from 0 to 60. You see how it corners. People hear tires screeching from all over the city as you and your one other occupant sling this bad boy around town ‘evaluating’ the bus. You then repeat the same process for ‘Vendor B’ and ‘Vendor C’. You aggregate your data. You correlated your data. You make pie charts about your data. You do ROI calculations on your data. You do comfort analysis on your data. You do handling analysis on your data. You made your ‘educated’ recommendation and purchased a fleet.

Day 1 of school rolls around and the first thing your brand spanking new fleet of school busses does is immediately do the one thing you neglected to test: they loaded up with kids and trudged along at 20 MPH safely around town. You start getting complaints. They don’t stop well. They don’t handle well. They don’t get good gas mileage. They bounce all over the place and your district has to send 2,000 kids to chiropractic care because you didn’t evaluate the bus under the conditions it’s going to be used in. Instead, you took it for a joy ride. You drag raced it. The one bus that went the fastest with a single guy in it, you bought. When you deployed it, it broke because you didn’t test it using real world scenarios.

Please, don’t drag race your evaluation Access Points. Test them like you’re going to operate them. That way you get a realistic view of how they’re going to behave in the real world. Do your self a favor. Stop joy riding your vendors gear and put it in the real world to test it.

This blog inspiration courtesy of @florwj . Go follow him. He’s awesome.

-Sam

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.