Building a Wireless LAN for Your SMB


I wrote about common Wi-Fi misconceptions earlier this week to address common mistakes made by businesses setting up a wireless LAN (WLAN). There is no denying that deploying a WLAN for the first time can be intimidating for SMBs that may not have the relevant expertise. To help decision makers or influencers along, I've made a short list of key decisions that companies deploying a Wi-Fi network will eventually be confronted with.


Security and Authentication


I think it is fair to say that businesses should not even consider the use of wireless access points (AP) that do not support the WPA2 encryption standard. In fact, some vendors even offer proprietary implementations where pre-generated encryption keys are used to further enhance security, while other capabilities on the security front include the ability to detect rogue, or unapproved, APs within the company walls.


Moving on, an unobtrusive and reliable way of correctly identifying and validating clients for their legitimacy is of equal importance. As such, businesses should ensure that common authentication and accounting services necessary for managing larger numbers of users such as RADIUS and Active Directory are supported. In addition, some companies may want to check for the availability of captive portals to facilitate "hotspot" services, or support for multiple SSID with VLAN tagging to segregate vendors or guests from employees; other WLAN solutions may even come with frills such as self-service guest registration for automated granting of Internet access.


Of course, many of the services mentioned above are generally only available on controller-based deployments, which we shall talk about below.


Figuring out Your Network Density


One factor that will heavily influence the budget is the anticipated count of laptops or wireless devices that will use the network. While a single AP should be adequate for small businesses with under a dozen users, scaling beyond 20 or 25 users could necessitate the deployment of additional APs for optimal performance.


In this context, a common mistake is to compare the maximum bandwidth offered by an AP with that of wired networks as the basis for estimating AP requirements. This is erroneous on two fronts: Wireless mediums require a far greater overhead than wired networks, and the radio channels used by Wi-Fi are effectively a shared medium. From my experience, it would be more accurate to compare the performance of an 802.11n (300Mbps) AP to that of a Fast Ethernet (100Mbps) hub. In addition, my simplified analogy above also does not factor in the potential interference from microwave ovens, cordless RF phones and APs from neighbors.


Given the explosive popularity of tablet devices and smartphones with built-in Wi-Fi capability, the caution here is that businesses are likely to underestimate the number of wireless devices that could start appearing on their premises.


2.4GHz, 5GHz or Both?


The decision for a 2.4GHz-only deployment or opting for more expensive dual-band equipment is likely to become a moot point very soon. For now, however, this decision is still relevant as dual-band gear is still substantially pricier, while the majority of wireless devices still do not operate on the 5GHz spectrum. Of course, it can be argued that new laptops are starting to support 5GHz, though businesses with old laptops and wireless adapters are out of luck.


The advantages of going 5GHz is multifaceted and relate primarily to the lessened interference on the 5GHz frequency range. Moreover, dual-band APs that can operate simultaneously on both bands effectively double the available wireless bandwidth (picture two hubs instead of one). Finally, certain brands of WLAN equipment can perform backhaul operations using the less-crowded 5GHz band while continuing to serve users on the 2.4GHz channels.


Managing the Access Points


The question is whether a dedicated WLAN controller applies when more than two APs are deployed. Of course, it is not impossible for administrators to independently configure up to half a dozen APs (or even more) without too much trouble. Ease of management aside, the presence of a controller offers compelling advantages that range from the more efficient sharing of radio frequency (RF) resources to achieving a better spread of clients between adjacent APs.


The downside is that these proprietary controllers do add some costs to a wireless deployment-and ironically is the reason why WLAN equipment from different enterprise vendors is not interoperable. I shall be writing more about the use of controllers in my next blog, so stay tuned!