Is Mission Critical Wireless ‘Mission Impossible’?

Date April 25, 2017 Author Comments Leave your thoughts

Mission Critical Wireless LAN

Mission Critical or Mission Impossible?

An increasing number of businesses place massive importance on their wireless networks and how critical they are to the day to day success of their operations – ‘Mission Critical’ is the most common expression of this.  Fair enough but how do you actually define ‘Mission Critical’ and, probably even more difficult, calculate what the consequence of failure in the network is?

In some instances the consequences are obvious; for example, a critical care unit in a hospital relying on transmission of patient data to a central monitoring point is truly a life and death scenario.

Other situations, for example, control of goods out scheduling and dispatching in a Distribution Warehouse could have purely monetary consequence in penalties for late deliveries, loss of customer business, etc.

Ultimately, of course, too many events could lead to the demise of the whole business.  Education is another great example; if loss of the network means that lessons cannot be delivered then the school has a real problem in meeting the needs of the students.

An Appetite for Risk?

It’s easy to say that the business must operate 24 x 7 but does it have to operate at full capacity all the time?  Would the loss of a couple of elements for a short period have significant consequences?

If the answer to these and all similar questions is ‘yes’, then we are probably into ‘Mission Impossible’ (or at least impossible within any reasonable budget!).

On the whole, though, we tend to look at the risk/reward equation; if the cost of failure coupled with the risk of it happening is greater than the cost of protecting against that failure then more protection needs to be added into the network.

It would be good if all these factors were purely objective; they’re not, of course.  Everyone has a different (subjective) appetite for risk; the costs of failure are estimated generally based on a wide range of factors, and the degree of protection required is some combination of the previous points leading to a price point which may, in itself, change the risk appetite.  Full circle!

We’re All About Wireless

So, what to do?  The total network including all internal and external connections is way beyond this article but Ensign is all about wireless networking so let’s take a look at that (some elements do, of course, apply to many other parts of the end-to-end solution as well).

First of all, eliminate those single points of failure! 

Even the wireless kit needs to connect into the core wired infrastructure somewhere so don’t route all the Access Points to a single switch – spread them around; you might lose some APs but with an intelligent distribution across switches, you won’t lose them all!

Think about the overall design; would you prefer a controller-based wireless solution or an inherently resilient controller-less AP only solution (such as Aruba HPE Instants or Ruckus Unleashed) with a centralised management platform?  If the former, use a resilient pair configuration and make sure that the two controllers are powered from separate sources so that a local power failure doesn’t take them all out.  A UPS will fix the power failure problem (although there’s then more decisions to be made on how long the UPS must hold the systems up for and how many batteries would that need…).

For extreme resilience, a three controller configuration will give that extra level of security.  Look at the AP layout; a ‘thin’ layout will run the risk of an RF black spot if an AP goes out while adding a few more with intelligent RF power management should be able to cover any RF holes resulting from a single AP failure (or possibly multiple AP failures if they’re not adjacent to each other).

Maybe 100% coverage 24×7 isn’t critical if most employees or systems are mobile – moving out of a black spot for a couple of hours probably wouldn’t be a drama.

Wireless Networks Designed for Success

The point of all this as you might have noticed in previous articles is to figure out up front exactly what is and what is not important.  Then the network can be designed to meet those needs.  Figure out the risk/reward piece.

Two controllers or three? Save a little cash at the risk of the occasional sleepless night at times of high activity on the network…up to you, but whatever you decide, at least you’ll have thought about it and will understand the risks rather than just worrying all the time about what might happen.

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Author Ian Price

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