All about DART

Yes, I’m writing a blog post on a connector. Just a connector. If you’re like me, you can appreciate the little things in life. This is one of those times that something little snuck past me and it wasn’t until now that I’m starting to fully appreciate it’s impact and importance. When Cisco launched their 2800/3800 APs, dual 5GHz was certainly at the top of the list of the most talked about features (see #MFD session here!). This came with some caveats (as all new features do) and using a separate set of antennas for the second 5GHz radio was the biggest. This is handled on the internal antenna models with an in-built extra set of antennas, but on the external antenna models, this presented a bit of a challenge. In the wide world of antenna connectors, in the Wi-Fi space, we commonly deal with RP-SMA, RP-TNC, and N-type connectors depending on your vendor and the deployment type. In the Cisco world, that’s RP-TNC for indoor APs. With a single, 4 element antenna today, that’s four connectors (or four, single element antennas). With two antennas, that drives the number of antenna connectors up to a whopping 8 cables you’re looking to have coming out of your AP! 8 cables, 8 connectors, it gets messy quick. Enter the DART connector:

All covered up!

All covered up!

DART revealed!

Inconspicuously located on the side of the AP, behind a little door, the new DART connector reveals itself in a complex looking array of pins and connectors in a tight external facing form factor. Here’s the interesting part though, this isn’t a new connector! In fact, it’s been shipping to the public for a little bit now in the form of the Cisco Hyperlocation module and antenna!

Hyperlocation with DART

Hyperlocation with DART

DART on Hyperlocation Exposed!

DART on Hyperlocation Exposed!

So, that’s all great and all, but what’s really *in* the DART connector? DART stands for Digital Analog Radio Termination and it does all of those wonderful things. Firstly, the analog antenna connectors that we use (so we don’t have 8 RP-TNC ports on our AP) are the 4 larger pins across the bottom of the connector.

Look at all those pins!

Look at all those pins!

When we use the DART to RP-TNC pig tail for backwards compatibility with shipping antennas, these are the connectors that map directly to the 4 RP-TNC connectors. In short, these are the 4 analog ports that carry the actual analog signal through the connector.

DART to RP-TNC Cable!

DART to RP-TNC Cable!

Fully assembled!

Fully assembled!

For existing RP-TNC based antennas

For existing RP-TNC based antennas

On the cable end!

On the cable end!

Which leave us with the extra 16 pins. Those are the ‘Digital’ piece of the DART connector and can be used for a variety of uses. Initially, this is used to identify the type of cable that is attached to the DART connector. For example, in the Hyperlocation module, this shows up on the AP details:

Circular Antenna

Circular Antenna

For the DART to RP-TNC connector, this is in the form of a simple resistor that maps two of the pins back to each other:

DART disassembled

DART disassembled

It’s easy to see that there’s quite a bit of left over functionality that could be used in a connector of this type. Today if we use very high gain antennas we have to have multiple models of APs (see the 3602p and 3702p). If we could identify the gain of the antenna by way of an automated mechanism, we could have the AP auto adjust itself to not exceed EIRP. Another potential use case is DART native versions of our existing antennas in a simple to use connector. Imagine not having to screw on connectors anymore! With a quick-connect antenna mechanism that auto-IDs the antenna capabilities to the AP, this could certainly be the new connector of choice for external antennas in the future!

With DART connector on edge.

With DART connector on edge.

Note the DART connector on the left.

Note the DART connector on the left.

The Cloud giveth, the Cloud taketh away

We all love ‘The Cloud’. It’s flexible, fast, always (mostly) available, and takes our business agility to heretofore unknown heights – but what happens when the service you’re using in the cloud goes a different direction than you need or want it to?

Meraki has been touting the Cloud flexibility as *the* single most important reason to move to their infrastructure management platform. This brings with it a whole host of great things like access-anywhere management, rapid feature development, and a whole new paradigm of how to configure your infrastructure equipment. In one move, Cisco has rocketed past the CLI based days of old, past ‘here’s a pretty GUI’ to 100% web driven, ‘don’t worry your pretty little head about it’ dashboards for everything from configuration, monitoring, troubleshooting, and deployment. It works and it works well.

Today marks the closing of Copy – a Cloud based file sync service from Barracuda and it got me thinking. When someone shudders their doors and it’s ‘just files’, you go to another Cloud based service provider – in this case Dropbox or box.com. What happens when/if Meraki goes away? Okay, they’re under the wing of big-brother Cisco now, so the chances of that happening are basically nil, but what if you ratchet that concern back a notch? What if they make a change you don’t like? What about ‘perpetual beta’ features such as the Remote Control that have been in beta since prior to the Cisco acquisition? What happens if you don’t pay your bill? Those of us familiar with Cloud services like Office 365 know that when you stop paying, you stop playing and for software based services (like Copy today) that doesn’t seem to as big as a deal to most people. What happens when that service is your network?

Remote control

Perpetual Beta features

When Meraki adds a new feature to their product, the Cloud enables rapid deployment of those features. This is good. What happens when they remove a feature you use such as WAN Optimization? As you an see here Meraki decided to retire what they perceived to be either a little-used feature or a feature that was too difficult to maintain to keep functioning properly.

WAN Opt

WAN Optimization, gone baby, gone!

What happens when Meraki decides to artificially cap the performance of your router (intentionally or unintentionally) to 50M?

Z1 Cap

Astute reddit users, always on the lookout.

While the WAN Optimization removal is clearly an intentional move and the Z1 cap is clearly unintentional, these both raise very significant questions about allowing someone else to be the ultimate authority for the features that are deployed on hardware you’ve purchased. What is your recourse when this happens? Open a support ticket? Make a wish? Roll back the firmware (hah!)? With no fail-safe mode of operation by design, when you lock yourself into a Cloud based infrastructure product, you are ultimately at the mercy of using features how and where they determine are best suited. Your only recourse is to scrap your gear if they make a decision to go in a direction that you no longer support. What is the environmental impact to this business model? How many Cloud-only products end up in landfills because of expired licenses? How much eWaste is generated because the product has stopped functioning (not through MTBF, but intentionally crippling through code)? You used to have options like Cucumber Tony and OpenWRT, but apparently Meraki has fixed the technical loophole that those folks used to use for the MR-12 and MR-16 Access Points by way of a Trusted Platform Module.

What is your take on Meraki and other Cloud based services that you operate your business with? Cloud based products are great and work as designed – but is loss of features something you consider prior to your investment in a solution? Does your organization rely on perpetually beta features that never seem to make it into production? Has a feature been ‘pulled out from underneath you’? What are you doing with that old AP/switch/firewall that is perfectly good hardware but you let the license lapse on? Inquiring minds want to know – please leave me a comment and let me know how you and your organization handles this kind of quandary!

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!

UX Domain APs

In the wireless world, we’re constrained by regulatory requirements. These are, at their core, different rules by which we must abide by when we’re operating wireless equipment. Each country has their own set of requirements and restrictions – each manifesting itself in some iteration of channel availability or power limitation of some sort. Until now, this meant that each country had to have it’s own regulatory SKU to prevent a wireless professional or other ‘non-professional’ installer from exceeding or violating that countries requirements. Cisco has worked around this particular issue with a universal SKU Access Point. In the past you would order a specific AP for a specific country. The astute Cisco-configurator would identify the country code in an AP model number (A for North America, N for Mexico, I for Egypt, etc.). The gory details of country code mapping changed occasionally which meant that it was almost a full time job for international companies to wrangle which SKU went where.

Note the UX domain model of AP, last in the list.

UX domain model of AP, last in the list.

Enter the ‘UX’ SKU of AP. These APs are designated by the country code ‘UX’ and are universal SKU APs, meaning one SKU can be installed in any country. The way we’re able to do this is by way of software defining which country the AP is operating in. Now, the FCC won’t just allow you to ‘claim’ a country code, so there are some specific restrictions to deploying a ‘world capable’ AP. Today, this means tying the AP to a specific user, then using a non-hacked device to determine GPS coordinates of where the AP is installed to ‘prime’ or ‘unlock’ the AP based on what country it’s physically located in.

This blog will review the two ways to ‘prime’ a UX domain AP and get you up and running in no time at all! The first thing you need is an un-compromised (not jailbroken) device with both online capabilities (an Internet connection) and GPS capabilities. Enter the smartphone. Most of todays smart phones meet this requirement:

Step 1) Head to your devices respective app store and grab the Cisco AirProvision application.

Don't ask me what the Android store looks like!

Cisco AirProvision in the Apple Store

Step 2) Plug in your AP and let it join to your WLC (this assumes you have things like discovery already taken care of). There are no UX specific join requirements so if you have regular Cisco APs joining your WLC, this part should be easy. Note that at this point the AP will be flashing ‘bad colors’ at you despite it’s radios being up and operational.

Unprimed AP

Unprimed AP

Step 3) Enable ‘Universal AP Admin’ on one of your secure (PSK or .1x) SSIDs that has internet access (WLAN tab -> WLAN ID -> Advanced tab -> ‘Universal AP Admin’).

Universal Admin

Universal AP Admin

Step 4) Join the above SSID on your unprimed AP.

Step 5) Launch the app on your smartphone and log into CCO (page 1) then your WLC (page 2).

Step 6) Click Configure!

Click Provision!

Configure!

That’s it! It’s a relatively straightforward way for your AP to know what country it’s at.

Primed AP!

Primed AP!

The good news is that you only ever need to prime a single AP in this fashion. Once it’s primed and comes back online, it will automatically include in its Neighbor Discovery Packets (NDP) UX domain info. Any other unprimed AP in earshot of these discovery packets will hear them and automatically pickup the country code of the already primed AP! Once you have primed a second AP by way of the NDP the priming sticks with the AP and you can then prime others off it in a cascading fashion – you can even re-prime the AP that you previously primed with the app!

NDP Primed AP!

NDP Primed AP!

While this may seem like unnecessary work for those that are single country entities, those that have to operate in multiple country codes may find that simplified ordering is a lifesaver – assuming your installers have a smart phone and a free CCO account. This can also help if your company accidentally ordered several hundred of these and you don’t want to RMA them. Remember that the country code priming sticks with the AP across reboots, regardless of location (unless you re-launch the mobile app to reconcile your installation).

Things to remember:

  • Your smartphone must allow location access (it has to know where you’re at after all).
  • You must join the SSID on your unprimed AP. Joining on a different AP won’t help you any.
  • You have to have 2.4GHz enabled on your WLC and SSID – an unprimed AP operates in 2.4GHz only so you have to be able to see your SSID.
  • You must have the country code you’re provisioning enabled on the WLC (Thanks Andrew!).
  • Your SSID must have internet access to allow CCO to be accessible.
  • NDP priming only works on other NDP primed UX domain APs or app primed UX domain APs – not ‘regulatory domain APs’.
  • Did you screw something up? You can reset the UX domain AP by performing a ‘Clear All Config’ on the AP page in the GUI (along with all of it’s other settings)!
  • When your AP primes, it reboots. This is the same if you use the app or NDP. Don’t be surprised if you app-prime one AP and it cascades a bunch of NDP reboots.
*Oct 26 14:16:35.003: %CLEANAIR-6-STATE: Slot 0 enabled
*Oct 26 14:16:41.783: %CLEANAIR-6-STATE: Slot 1 enabled
*Oct 26 14:17:08.719: %CDP_PD-4-POWER_OK: Full power - NEGOTIATED inline power source Writing out the event log to flash:/event.log ...
*Oct 26 14:19:50.339:  **************************** UNIVERSAL AP PRIMING ***********************
*Oct 26 14:19:50.339:  Action completed: regulatory domain values 0x0 0xB are written. Now trigger AP reload
*Oct 26 14:19:50.507: %SYS-5-RELOAD: Reload requested by UAP DIE process. Reload Reason: UNIVERSAL AP PRIMING SUCCESSFUL .
*Oct 26 14:19:50.527: %LWAPP-5-CHANGED: CAPWAP changed state to DOWN
*Oct 26 14:19:50.727: %CLEANAIR-6-STATE: Slot 0 down
*Oct 26 14:19:50.727: %CLEANAIR-6-STATE: Slot 1 down Write of event.log done

You can see above the log from an AP that was previously online. This AP was unprimed when it powered up, came online with radios up and then after several minutes received the NDP prime message and auto-rebooted. Easy, but potentially disruptive!

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

MythBusters WiFi: Xirrus

I’ll be the first to admit that when I see something ‘out of the norm’ I shudder and have a knee-jerk reaction that is not always positive. There is so much success around the tried and true enterprise approach to wireless of using omni directional antennas that when you see someone intentionally deviate from it, it can be jarring to say the least! I’ve had the pleasure to be present at the Xirrus Wireless Field Day sessions for WFD5 and WFD6 and I can honestly say that they did a superb job of taking a contentious topic and addressing it head on. For those that are unfamiliar with the Xirrus product, their unique approach to wireless is to stack multiple Access Point radios into a single housing and use highly directional antennas to create an ‘Umbrella Corporation logo’ of coverage:

Image likely copyrighted by Capcom

(it should be noted that I do not believe that Xirrus is somehow evil, involved in genetic engineering, or otherwise a bad company – the logo is simply an easy way to represent a high degree of directionality from a centralized point)

Adding multiple radios into a single housing is not a unique approach. Most everyone on the market starts with two radios in their Access Points and you can even find a handful of three-radio solutions, but Xirrus takes this approach to the next level by stacking as many as 16 radios into a single Access Point! The challenge that other manufacturers do not need to address is overlap. In a standard two or three-radio approach, you typically operate one radio in 2.4GHz and the other in 5GHz (and for those rare 3rd radio guys, they usually stick that radio in monitor or listen-only mode). Tack some omni directional antennas on those bad boys and you’ve got yourself an AP! Xirrus however, intends to have multiple radios in a single AP operate on in the same frequency. This presents some challenges about the efficiency you can gain from having more than one radio in the same frequency in the same physical package (AP). At WFD5, there was much gnashing of teeth regarding how you accomplish this in one package. I’ll not go over the gory details, the video is posted here. Xirrus came back to WFD6 and brought with them their Director of RF Engineering, Avi Hartenstein and tacked the conversation head on.

My goal was simple with this post. I wanted to prove that directionality does exist in the Xirrus product once and for all. I was able to acquire a 4 radio array and decided that the best approach to visualize this purported phenomenon was to actually survey with an AP in an area with no obstructions (scientific, no?). I took the array, statically assigned one of the radios to a fixed channel, turned its power down to -15dBm (yes, they go *that* low!), and took it outside. The results speak for themselves:

 Umbrella logo likely copyrighted by Capcom

Ladies and gentlemen, you saw it here first (or maybe not) – the myth of the Xirrus wedge is real! You can see near the bottom of the image where the AP was placed (at random orientation). I peeled this wedge view out using Ekahau’s Site Survey application after quite a walk outside in the cold. This directionality is fairly easy to see even with my coarse sampling outside. It should be noted that it will be near impossible to visualize this dramatic of a wedge indoors however due to the prevalence of those pesky attenuators otherwise known as walls and furniture.

I’ve seen my fair share of wireless deployments, I know what I’m comfortable with, I know when I move outside of my comfort zone. An experience I reference often is an educational facility that was using directional patch antennas indoors on 10 ft ceilings pointed at the ground. While this is a startling design, when I dug deeper into their design methodology, I discovered that they surveyed using the exact model of antenna and AP that was deployed, correctly visualized the resultant zone of coverage, and validated that this met their applications need. While not a solution I would lead with, there was no fault with their design methodology or implementation, and the infrastructure operated as designed. When you tackle a Xirrus deployment, I would advocate the same approach: understand your needs (throughput, density, coverage, etc), and design to meet those needs using the gear you will be deploying. Survey what you deploy, deploy what you survey. In the Xirrus world, this presents a few design choices to consider:

1) Orientation of the AP.

The Xirrus array has a compass in it. Use this compass to determine the orientation of your array during the survey and ensure that when it gets deployed that this lines up correctly (use the logo on the housing if you need to).

2) Oversubscription.

You must pay close consideration to the number of uplinks to your array and balance this with your deployment expectations. Oversubscription is nothing new so don’t let this scare you – just be aware that you’re moving your uplinks (and potential bottlenecks) further up the line (closer to the AP). This is going to be particularly important as you consider updating your array to newer technologies such as 802.11ac.

3) Powering the Array

Ensure that you have made concessions for powering the array. This will likely require an external power injector but sourcing them along with the array should not be problematic.

4) Antennas change with the modules.

One of the most insightful things I learned from the WFD sessions are a reinforcement that the antenna is part of the radio module. When you replace that module, you replace the antennas that are a part of that module. This could potentially impact the RF of your deployment and will most assuredly change the visualization of your survey data.

Xirrus uses highly directional antennas in a unique way to extend the reach of a radio. This coupled with a low powered radio gives you a number of excellent design pieces for most any wifi environment or need. Pay close attention to the number of radios that you need, apply some logic and reason to your design (don’t expect 8 of your 16 radios to operate in 2.4GHz for example) and make sure your celling has sufficient mount points. The arrays can be weighty. 🙂