Clueless about wireless?

Enterprise WLAN systems are still far from becoming commodity products, which is good news for consumers looking to benefit from the increased choice and value that competition will bring. There is now a multitude of choice and the introduction of newer architectures, in place of the regular switched AP topology we have become comfortable with over the last couple of years. But all of this means that without a solid knowledge of their advantages and drawbacks, window shopping for such products is a little like riding without a saddle. So what do you need to know to deploy wireless, and how can you get through the bewildering array of options with the least blood, sweat, and tears? Here’s some of my own insight.

The first choice you need to make is on the deployment topology. Large enterprises favor a datacenter appliance that can manage several hundred access points simultaneously. This has the side effect of separating the administration of the wired and wireless networks, creating an additional management burden, but also increasing the ability to secure the network without disrupting the existing wired infrastructure. Medium enterprises can choose to deploy a wireless system managed by PoE edge switches. These devices are designed to have a low cost premium over regular non-WLAN switches, and allow for a very expansible deployment with gradual buy-in, as the demand for WLAN increases.

In general, it is important to understand the implications of varying levels of centralisation or decentralisation of management, control and intelligence. In some environments, such as in conference facilities, it makes sense to use a device that integrates multiple access points and sectorised antennae – providing both throughput density and range through signal gain in one box.

In the headquarters and the carpeted space, many early WLAN deployments started in the conference room or the executive suites, and then were expanded to encompass other parts of the facilities, mainly for connectivity purposes. The prmiary downside of a ‘creeping connectivity zone’ approach is that the deployment that results is often unsuitable for providing more than connectivity. For example, an organization could choose to host voice or asset tracking (also known as active RFID or locationing) services over the WLAN. As opposed to a connectivity deployment – which can have coverage holes but has the benefit of being operable with a minimum number of access points – voice requires ubiquitous coverage and a consistent signal quality throughout the facility. Asset tracking is even more demanding, requiring a well-planned arrangement of APs that allows for triangulation, with accuracy ranging from several dozen to ten feet, depending on deployment planning and signal quality.

For branch offices, there is an option to provide a completely unwired office. This turns out to be a balancing act among competing usage scenarios. On the one hand, as utilization goes up, performance at the air interface will inevitably decline. The 2.4Ghz spectrum is already rather crowded and interference prone, and, in a small office that is bordered by multiple networks from neighboring offices, maintaining a high level of performance will be difficult. Moving to the 802.11a standard in the 5Ghz spectrum is a possibility worth considering, since it is much cleaner from an environmental interference standpoint, far less utilised, and since the costs have come down significantly over the past year. Ultimately, this is a question of the kind of applications that the WLAN will be used for. Almost anything will suffice for basic connectivity, but VPNs and apps requiring session-continuity could be somewhat impaired. Heavy-load apps like multimedia and file transfers would be difficult to host altogether. However, a wireless office could also bring considerable organizational benefits, especially in combination with collaborative apps.

For providing outdoor campus connectivity, there is the option of going with a dedicated mesh network deployment. Simple 1-radio solutions will perform fine in most cases where basic connectivity is the goal, and performance can be purchased at a premium with multiple radio systems. There is also the option of going with outdoor APs from your primary WLAN vendor. Some of these combine features of mesh-networks and are able to tunnel back to the indoor network wirelessly over a separate backhaul radio, drawing power from standard electrical fixtures on lighting poles.

Small branch offices can benefit from a remote AP, which plugs directly into a broadband connection, securely tunnels its way back to the corporate network, and acts like an extension of the corporate network, with the same management capabilities and enforcing the same security policies that govern in the headquarters. This low maintenance approach is ideal for small teams of mobile workers, and especially for locations that are too temporary to merit installing more substantial infrastructure. For more permanent solutions, there is a selection of remotely-manageable business-class routers that can coordinate several access points, and this can be a good alternative to either a one-AP solution or to putting in more substantial infrastructure.

802.11n has been a buzz-worthy topic, probably as much for the antics of the standards committee, as for actual benefits that it will bring. Many vendors are now touting n-readiness through replaceable radio cards and software upgrades. This is certainly good, and a benefit for investment protection. However, the incremental benefit of 802.11n over 802.11abg will be lower than the initial boost offered by 802.11g over 802.11b, and there are few practical reasons to hold off on deployment.

Finally, guest access has emerged as a leading WLAN application and remains one of the most immediate ways to derive value from the WLAN. Most vendors offer a guest access solution (integrated or as a software add-on), and this is always worth exploring. There is great benefit to being able to create security and network access profiles for several different kinds of temporary visitors, which can be activated by the receptionist upon the guest’s arrival on the premises.

The cost of acquiring a WLAN system marks it as one of the cheaper investments in the IT universe, even after factoring in the installation and integration costs. For this same reason, it is able to deliver excellent value for the money spent, and substantial return on investment. Our research at IDC has consistently shown a number of positive trends in WLAN deployment. For example, organizations of all sizes are increasingly treating WLAN as a strategic investment – moving it to reside under the purview of the CIO’s office and planning to use it to host mission-critical or money-saving applications. From a connectivity perspective, while most organizations that have a WLAN have it deployed only to a limited portion of the workforce, most of those organisations are also expanding or planning to expand their deployments to a larger proportion. Finally, there is a social aspect to WLAN in that has become important to attracting and retaining human capital. Corporate purchasing of computers has been shifting toward mobile form-factors and WiFi has become pervasive in the public space. Accordingly, an expectation has arisen that organisations that look to provide their employees with a productive work environment should also provide wireless connectivity, and this expectation has been particularly strong in organisations that are engaged in engineering and creative work. As IP convergence continues apace and the enterprise IP network becomes ever-more strategic to the operations of the organisation, there is certain advice you should keep in mind when architecting your WLAN deployment. Include both wired and wireless in plans to support 802.1X authentication, plan for a comprehensive security strategy at the client, transport and link layers that involves both wired and wireless and ensure that your network supports segmented guest access. Also, design a network that can support location and voice, and have a plan to get wireless into areas where you currently don’t need it, but might in the future, such as stairwells or elevator shafts.

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