By Jim Geier
There are many access point vendors now with products on the market, leaving you with a tough decision on which one to use. Some of these access points barely satisfy the 802.11 standard, making them most suitable for homes and small offices. Others have rich features that extend well beyond the standard, which are ideal for higher-end, enterprise-wide solutions.
If you’re deploying a small wireless LAN, then you’ll likely search online for the least expensive access point using a site like WirelessCentral.net or purchase them at your local office supply or home electronics store. For enterprise solutions, you need to spend some time comparing access points to make the best decision based on requirements. Features that seem insignificant in a smaller wireless LAN often have tremendous payoffs in larger ones.
Selection criteria to consider
Standards. There are two primary standards for access points today: 802.11a and 802.11b. Carefully decide on which standard to use before shopping for access points. If you opt for 802.11a, the list of available vendors will be smaller. Not many are offering 802.11a yet.
Interoperability. To guarantee interoperability, choose products with WECA (Wireless Ethernet Compatibility Alliance) Wi-Fi certification. This maximizes cross-vendor interoperability: Wi-Fi-certified radio NICs will interface effectively with a Wi-Fi compliant access point. Keep in mind, however, that Wi-Fi uses 802.11b as a basis. WECA is still working on Wi-Fi5, which focuses on 802.11a product interoperability.
You should also ensure that the 802.11b access point vendor has a migration path to 802.11a in case the future dictates needs for higher bandwidth. Some companies solve this problem by offering dual slots in the access point or replaceable Mini-PCI wireless NICs. Interoperability will become less of an issue as multimode radio NICs and access points become available, but that won’t occur until late 2002.
Upgradeability. Because wireless LAN standards are evolving rapidly, the access point should support firmware upgrades. It’s also advantageous if the firmware upgrade can be done from a central access point, which then automatically distributes the upgrade to the other access points on the network.
Ruggedness. If the access point will reside in an office, plastic casing should suffice; however, warehouses and manufacturing plants will likely require the more rugged, aluminum casing. Thus, consider the operating environment and select an access point that is tough enough.
Regulatory. Vendors must certify access points with the appropriate regulatory body before offering them for sale in a particular country. This is a slow and tedious process. As a result, be sure the vendor has products available for the applicable country, especially if you’ll be deploying the wireless LAN outside of the U.S.
Operating Temperatures. Access points don’t have any problems operating within typical office environments where temperatures are comfortable for humans. A warehouse or manufacturing plant, however, can have temperatures that are very hot or cold depending on the local climate. Consequently, ensure the access point can withstand extreme temperatures if requirements call for these types of locations.
Security. The 802.11 standard offers wired equivalent privacy (WEP) for encrypting data sent between wireless stations. Many sources, nevertheless, have shown the vulnerabilities of WEP. As a result, vendors offering enterprise-grade access points generally include enhanced security features, such as IEEE 802.1X along with dynamic key allocation and management. Carefully assess needs for security, and choose an access point having adequate security mechanisms.
Range. Access points with range enhancements are beneficial to minimize the number and overall costs of access points. In general, longer range reduces overall costs because of the need for fewer access points. Be careful, though, when comparing access point specifications from different vendors. One vendor may boast long range capability, but they may be using a higher gain antenna. Other access points, if using this higher gain antenna, may offer the same or better range. The idea here is to read the test specifications carefully.
Installation and Support Tools. For enterprise wireless LANs, installation and support tools become an important aspect when choosing access points. In general, most access points will have various methods, such as Telnet and HTTP, for support staff to configuration and management purposes.
Be cognizant of other enhanced features that can reduce installation and support headaches. For example, installers must choose proper radio channels when installing multiple access points within close proximity to minimize inter-access point interference, which can degrade the performance of a wireless LAN. Some access point vendors make life much easier by offering automatic channel selection. The access point senses the presence of other access points and attempts to adjust to a quieter channel.
Transmit Power. Most access points will transmit at different power levels, such as 30 and 100 Milliwatts. Some applications may require relatively lower power levels, such as when deploying access points close together to boost capacity. If you need extremely low power levels, your list of potential access point vendors will be much smaller. Some access points will go as low as one milliwatt, but not many do.
Antennas. Even though the antenna is a passive device, it’s a vital element of a wireless LAN. Various access points have non-removable antennas, and some have external connectors to provide flexibility in choosing antenna types. Those that support external antennas provide the most flexibility, which is especially important for enterprise solutions. Vendors generally sell different types of antennas, or you can buy through a third party company specializing in antennas.
Price. Price obviously plays an important role when making a decision on what products to purchase. An access point with a higher price, though, could be the best one to choose. As a result, carefully consider the installation and support tools that a higher priced access point may include. It could be worth the extra money if the higher priced access point saves considerable time when installing and supporting the wireless LAN.
Availability. Even though a vendor may have a particular access point on the market, they may have difficulty fulfilling your order in time. This is especially true if you’re purchasing a new model. Allow some padding in time estimates for new products, and consider availability when comparing vendors.
You can use the above criteria to produce a list of the top several access point vendors and possible select a preferred vendor for satisfying your requirements. For larger projects, however, also consider evaluating several of the products through testing before making a final decision. For example, you could install a small prototype in a lab setting to compare and contrast security mechanisms and performance of your top three vendors. There’s nothing better than a live comparison, but be sure to judge them equally using common test criteria.
Jim Geier provides independent consulting services to companies developing and deploying wireless network solutions. He is the author of the book, Wireless LANs (SAMs, 2001), and regularly instructs workshops on wireless LANs.
Reprinted from www.80211-planet.com.
