Venturing Into the Wireless Future

The AirStation g54 is based on another first--Broadcom's 11g chipset (the company never offered an 11b or 11a chipset)--so I was not surprised to encounter problems with performance, range, interoperability and management. If there's a silver lining, it's that early-release products help us find problems that need to be addressed before the technology is enterprise-ready.

The AirStation g54 is intended to support clients of the faster 802.11g standard while maintaining legacy support of 802.11b users. To be backward-compatible with 802.11b, 11g relegates administrators to the three nonoverlapping channels of 11b--five short of its 54-Mbps rival, 802.11a. This, along with the device's lack of PoE (Power Over Ethernet) capability and the fact that it isn't designed to mount on a wall or in a drop ceiling but rather to be placed on a desktop, make it difficult to deploy the AirStation g54 even in a SOHO setting.

I configured the AirStation g54 through a simple utility and then accessed the Web management pages from a PC on the same subnet. Because the device is an access point and broadband router in one, it is set up to run NAT (Network Address Translation), which shares one external IP address with multiple, privately addressed PCs, and to hand out addresses via DHCP. However, both these features can be disabled.

I wanted to get a feel for how the AP handles file transfers to mixed nodes and how well it can handle the load of many clients transferring simultaneously, so I tested throughput using 11g and 11b clients alone and simultaneously. I plugged the 11g and 11b clients into a 1.2-GHz Microsoft Windows XP laptop and batch-transferred 1,000 iterations of a 1-MB, TCP-based unidirectional long-file receive to the various setups. The results were less than spectacular (see "Throughput Results," below).

The AirStation g54 offers a proprietary turbo mode for 11g clients. Unlike the turbo modes of 802.11a APs, the g54's turbo mode doesn't boost the data rate higher than 54 Mbps; it simply makes more efficient use of the available bandwidth. To do this, the g54 operates using only the packet timing of 11g clients--9 milliseconds--ditching the 20-ms timing required by 11b traffic. But when using the turbo mode, I was afforded only about one extra megabit per second in most test environments, and had to sacrifice compatibility with 802.11b. Still, you want high performance and are willing to forgo 11b compatibility, 11a is a better solution.SUB: Range Counts

To test the device's range, I placed the g54 in an elevated position in a hallway of the building where our lab is located and ran a continuous ping to the unit's static IP address from various locations. Range results based on packet loss proved to be one of the g54's stronger points, but the device's 11b range results were still just 75 percent of our 11b control tests based on Cisco's Aironet 350 AP. Interestingly, the maximum ping range for 11g slightly exceeded that of 11b. I expected the range of a 2.4-GHz OFDM system to exceed that of a 5-GHz 11a system, but the AirStation g54 appears to closely match the range of our top-performing 11a AP, Proxim's Harmony.

The ranges for AirStation are limited when compared with those of other competing APs, but they should suffice for most SOHO installations. Additionally, their near-concentric nature will please administrators interested in simple deployment. The AirStation g54 has support for an external antenna as well, which would likely extend its range, but true to its SOHO roots, the unit doesn't let administrators alter output power levels.

SUB: Interoperability

Because part of 802.11g's appeal is that it protects current 11b investments, interoperability with the broad array of 11b devices is of paramount importance. My initial tests using Cisco 350, Proxim Orinoco and Symbol Spectrum24 cards, three of the most widely deployed 11b NICs, resulted in only the Orinoco Gold cards associating with the g54. Buffalo shipped me a replacement gateway just prior to deadline that resolved this, and reps promised that subsequent versions won't have the compatibility problem.Roaming was also problematic and required that the 11g cards be reinserted to regain connectivity. Typically these devices aren't used for more than creating hotspots within an office or home setting, so the need for roaming with a SOHO gateway such as the g54 isn't great. Unfortunately, this problem wasn't fixed by the updated firmware, but Buffalo says it will look into this once the company can re-create the problem in its own labs.

The AirStation g54 fails to address some of the key security concerns in wireless networking. The device supports WEP (Wired Equivalent Privacy) keying up to 128 bits and basic filtering options, and its much touted integrated IDS (intrusion-detection system) will detect basic intrusions and can alert administrators via e-mail or popups, though it can only send alerts to the computer on which Client Manager is running. Compatibility with the common 802.1x standard is noticeably absent but Buffalo promises upgrades to provide for AES encryption and VPN support in the near future.

Although Buffalo says its product is intended for more than home and SOHO use, the unit's lack of SNMP support, central management utility (other than the limited Client Manager) and inability to save an access point's settings to be pushed to other APs makes for quite an administrative ordeal for larger installs.

Currently, a dual-mode 802.11a/ 802.11b system, with all its deployment challenges, is the best solution for organizations that need higher speed and backward compatibility. And though 11g has the potential to deliver a viable and easy-to-deploy dual-mode solution, the technical problems associated with running multiple radio technologies in the same band will likely force some performance trade-offs. Meantime, products like the AirStation g54 may fill some niche needs in the home and small-office market.

Jesse Lindeman is a research associate at the Center for Emerging Network Technologies at Syracuse University. Write to him at [email protected].Post a comment or question on this story.