Over the next year or so, second generation wireless local-area networking (WLAN) technology will mature and become mainstream. During this period, IT and telecom managers will face a new range of planning considerations.
First-generation WLANs are based primarily on stand-alone access points
(APs) and have limitations in security, quality of service (QoS) and handoff capability — good enough for small offices and hotspots. Second-generation WLANs will address these limitations by adopting new standards, which will foster the deployment of enterprise-class WLANs. However, as usual, vendors are using different approaches while the industry arrives at a consensus. One approach requires proprietary client software, thereby raising the ugly spectre of vendor lock-in. Hopefully, this will not become a trend.
The first key standard is 802.11e, which addresses QoS and paves the way for voice and other real-time applications. Second is 802.11i, which addresses security. Third is 802.3af, which covers power over Ethernet (PoE). Fourth is 802.11n, which is intended to enable throughputs of at least 100 Megabits per second (Mbps) but might not be completed for one to three years. Also further out is Fast Roaming (Fast Handoff would be a better name) which is being addressed by a study group of IEEE 802.11. Its main objective is to reduce handoff time, which is particularly useful for voice.
Perhaps the most contentious issue is the search for a standard protocol between WLAN switches and APs.
At one level, the issue may be seen as a battle between supporters of “”thin”” APs and supporters of “”fat”” APs. At another level, it may be interpreted as protection of proprietary systems. By centralizing more of the intelligence in the switches and routers, the “”thin”” AP approach could result in lower costs and easier network management. But, without a non-proprietary interface, customers would be forced to purchase all their APs from one vendor.
One of the biggest WLAN drivers will be the growth of voice over WLAN (VoWLAN or VoWi-Fi), which will increase with the demand for IP PBXs and IP Centrex. Network planning activities should link WLAN plans with IP telephony plans. Dual-network handsets (cellular and WLAN) will further drive demand, in some cases challenging the need for desktop telephones at all. In all likelihood, the first dual-mode handsets will not enable handoff.
Planning for 2G WLANs will differ among enterprises, depending on requirements, planning horizon and the amount of legacy equipment already deployed. Nevertheless, a framework for planning can be created by considering each of the above developments along with the following choices:
1 — Move early or wait until standards are incorporated in the products;
2 — If moving early, consider only solutions that use elements of standards, or risk using proprietary solutions;
3 — Maximize use of legacy equipment, or write it off;
4 — Consider a single-vendor solution or a multi-vendor solution;
5 — Tightly couple WLAN planning and IP telephony planning, or loosely couple them;
6 — Include dual-network handsets in plans, or do not.
In addition to these choices, plans should address possible interdependencies between the enterprise WLAN, WLAN hot-spot services, and cellular services.
