Designing The Next-Generation WLAN

Designing a WLAN has never been easy, but today it's exponentially more complex with an explosion of smart phones, tablets and other devices, a wide array of applications, and workers who are accustomed to working anywhere, anytime.

"It's a moving target," Lee Badman, wireless network architect at Syracuse University and a Network Computing contributor, said in a workshop at Interop Las Vegas last week. "There are a lot of wrong ways to do things, but no one right way."

Badman teamed with Keith Parsons, a WLAN consultant and managing director of Wireless LAN Professionals, to present "From BYOD to 820.11ac: How to Build A Next-Generation Mobile Infrastructure."

Designing this next-generation WLAN requires a shift from a control paradigm that focuses on securing devices and controlling application access to an open paradigm of 100% wireless access, Parsons told attendees. In this open paradigm, users can work anytime on any device, video and voice are everywhere, and identity is the new perimeter.

"We're designing the next-generation of networks that need to be around five years. What will employees be using in five years? We need to design for things we can't even imagine," he said.

Moving to 100% wireless requires a detailed WLAN design process, Parsons said. Coverage is the easiest part of design, but he warned against adding access points without ensuring the design can provide frequency reuse. "Know when to say no," he said.

For added WLAN capacity, more spectrum is needed, and it must be efficient, he said. The WLAN design must also minimize medium contention (the number of APs and clients that can "see" each other) and reduce co-channel interference (which can occur from neighboring WLANs).

The design must account for a wide variety of devices with various data rates, applications and throughput needs, Parsons said. Define requirements in as much detail as possible, then once the WLAN is installed, "you need to come back and validate it," he said. "It's the same way we've designed wired networks -- define requirements, design to meet the requirements, and verify."

[Can the WLAN industry and its highly proprietary systems play nice with a technology that's poised to be a poster child for interoperability? Read Lee Badman's analysis in "SDN And Wi-Fi: Will They Ever Be Friends?"]

The workshop also included a discussion of client issues in the next-generation mobile enterprise. Badman said organization must have a policy that details what users can and can't do on the WLAN. Onboarding tools that provide some level of basic checks on a device before allowing network access are another must-have item.

On a BYOD policy, it can be easy to say no to certain devices such as Google Glass, but keep an open mind, Badman said. At the same time, "know your BYOD limits," he said, and advised saying no to devices with radios that require legacy (802.11 and .11b) data rates. Also, heavily scrutinize those that can't do enterprise WLAN security or that require hyper-specific design, such as Bonjour-based devices, he said.

802.11ac also was a major topic during the workshop, which examined the technical benefits of 11ac over 802.11n, what the second wave of 802.11ac products will bring, and the pros and cons of switching to the new standard. Badman described the reasons why an organization would want to consider adopting 802.11ac:

- Shopping for Wi-Fi for the first time

- Upgrading from a/g or early 11n and have good Cat5E or better cabling

- Anticipating lots of mobile clients

- Equal or near-equal cost on 11n vs 11ac

- Have long refresh cycles and are due

- Have spaces where dense coverage is of concern

- Looking to draw down Ethernet access in favor of highest-speed possible mobility and portability

- Want to leverage new features that often are delivered alongside WLAN standard updates at the AP/controller/cloud management code

802.11ac concerns include: the availability of only Wave 1 products currently, with a hardware swap required for Wave 2 products; most APs require 802.3at PoE+; you need a minimum of one Cat5e or better cable run per AP; and client device pools that aren't 802.11ac capable.