Residential and small office users have been enjoying the benefits of 802.11g products since the beginning of this year. For corporate customers who crave technological stability on the other hand, the letter “g” was not in their alphabet owing to the lack of a final standard.
With the recent ratification of 802.11g, enterprise WLAN vendors are no longer adhering to “Plan b” and are starting to embrace the newer technology. Proxim was one of the first out of the gate with an 802.11g version of their ORiNOCO AP-600.
The AP-600 is a strong product that gives administrators a great deal of control over both the WLAN itself and how it interacts with the wired distribution system. On the other hand, the unit’s plethora of features can sometimes make the AP-600 difficult to configure, increasing the product’s learning curve.
The newest AP-600 carries a street price of about $339, and utilizes the Atheros AR5002G wireless chipset. The newest AP-600 has the same physical configuration as previous versions, using a miniPCI radio module and a proprietary connector for an external antenna. Its metal stand facilitates placement on a desktop, or wall or ceiling mounting, and if you remove the plastic cover it’s rated for installation in a ceiling plenum. The unit supports Power over Ethernet
As is befitting of a corporate or enterprise access point, the AP-600 offers a wide variety of customization features and affords administrators wide latitude to configure countless access point settings. Seemingly every characteristic of the AP-600 is adjustable, save the unit’s color.
Configuration and administration of the access point can be performed a variety of ways. There is of course the ubiquitous browser-based method, but you can also configure the unit via a CLI through either a Telnet or serial connection. The AP-600 also offers seven groups of SNMP traps, so you can access or monitor the device via a management application like HP OpenView. (Each access method, incidentally, carries its own individual password.)
The AP-600 is easy to get quickly operational at a basic level, but mastering the product’s feature set will likely take some time. The browser-based, tabbed configuration interface is clean and well-designed, but it’s not always obvious under which category or sub-category a specific feature can be accessed. Interdependency between certain features can lead to configuration mistakes, which the AP-600 notifies of with the unhelpful generic message: “error updating parameters”.
I also had the browser-based interface lock up on me on numerous occasions. Fortunately, simply closing and restarting the browser was all that was necessary to regain access to the unit.
There’s a link to online help provided within the interface, but unfortunately it was not operational. This ensured frequent trips to the online documentation (provided in both HTML and PDF format) hunting for particular items or information. As it turns out however, the docs pertain to a number of different devices in the product line, making it a bit harder to find the information on features relevant to your particular model.
Once you get past these usability issues, the AP-600 reveals itself to be a capable and powerful access point. The AP-600 offers administrators the ability to firmly control the flow of traffic within the wireless network, as well as between the WLAN and the wired network. Numerous filters can be applied (by Ethernet protocol, TCP/UDP port number, or MAC address), at either the WLAN or Ethernet interfaces — or both.
The AP-600 also offers several ways to optimize and conserve WLAN bandwidth availability by cutting down on unnecessary traffic. One is to block communication between WLAN stations (also useful as a security feature in public access scenarios). Another is by supporting Proxy ARP, which lets the access point respond to ARP requests on behalf of wireless clients, letting them remain in power saving mode and cutting down on broadcast traffic.
If you don’t mind spending a little bit of wired bandwidth, the AP 600 has a link integrity feature which will periodically ping up to fiv addresses on the wired network to verify connectivity (if distribution system connectivity is lost, the unit drops all WLAN associations).
Like most WLAN devices, the AP-600 enables administrators to perform firmware upgrades and download and upload configuration files via the browser. It does, however, require the use of a TFTP server in order to perform these functions, and Proxim provides the SolarWinds 2001 Standard Edition on the product CD for this purpose.
The AP-600’s radio has four operational modes: 802.11g-only, 802.11b-only, mixed b/g, and “g Wi-Fi”. The b-only mode in particular could be useful for organization that wants 802.11g in the near term but are content with a garden-variety 802.11b device right now. All modes offer selectable transmit rates, as well as an automatic channel select feature which scans the airwaves and sets the unit to an unoccupied frequency.
The current iteration of the AP-600 doesn’t have the ability to reduce actual transmit power, for purposes of contouring of a coverage area. Proxim said this feature will be introduced in version 2.4 of the firmware, due for release in October.
One handy capability of the AP-600 is the ability to segment the wireless network by defining up to 16 VLANs
For WLAN encryption the AP-600 supports either WEP (when paired with Proxim ORiNOCO client cards, it supports up to a 152-bit key length for 802.11b or g) or WPA. In addition to WPA, MAC filtering and 802.1x client authentication via RADIUS are supported as well. It can specify both primary and backup RADIUS servers, and because the AP-600 can be a DNS client, you can specify them by FQDN as well as IP address.
Throughput performance was tested against an ORiNOCO 11/a/b/g Client ComboCard. In g-only mode, the AP-600 posted a very typical 20.99 Mbps of throughput at 10 feet. Throughput performance remained high and within double digits up to 100 feet, where it dropped to the 5.5-6 Mbps range for the final two distance intervals.
In my experience, AP’s without external dipole antennas tend to provide weaker signals at the more distant ranges in my test environment, so I attribute this to the vagaries of my particular location rather than any inherent characteristic of the AP-600.
I did not conduct a test run with WPA enabled. Although it was fairly simple to get it working on the AP-600, it couldn’t be enabled on the client card.
In mixed mode, the AP-600 throughput dropped about 10%, to 17.79 Mbps as a result of the switch to mixed b/g mode. Associating an 802.11b client with the AP during a test run degraded performance 35% from maximum, to 12.9 Mbps. A run with both clients simultaneously resulted in an aggregate 8.07 Mbps of throughput with each client getting roughly equal amounts — 4.39 Mbps for the g, 3.71 for the b.
This last test scenario was the most interesting and surprising, since many previous 802.11g access points (albeit from the SOHO segment of the market) typically provided higher levels of 802.11g and aggregate throughput (10 Mbps or more) in mixed mode, at the expense of the b client, which typically struggled to achieve 2 Mbps.
Part of the explanation would seem to be the fact that the AP-600 doesn’t currently support the Atheros Super G frame-bursting mode. That’s not a shock, since each chipset vendor has their own proprietary method, and vendor-specific technologies often don’t do well in mixed (i.e. corporate) environments. Also, according to Proxim, the AP-600 uses the RTS/CTS method rather than the lower-overhead CTS-to-self in order to ensure 802.11b clients have access to the medium in mixed mode. These two facts seem to explain the mixed-mode throughput results. Clearly, the AP-600 is, if not prioritizing access for b clients, is giving them generous access to the airwaves.
On that subject– according to Proxim, the AP-600 can support a theoretical maximum of 250 clients with WEP disabled (WPA figures weren’t available). That number drops to 120 with WEP turned on and 88 with 802.1x authentication enabled.