Wireless Bridges Span the Divide

May 1, 2000

RadioLAN Wireless Campus BridgeLink Model 347

Most vendors have a tendency to overstate the performance capabilities of their products, but RadioLAN's claims are justified. The company advertises its Campus BridgeLink as a 10-Mbps product--the most modest performance rating among the devices in our tests--but imagine our surprise when the BridgeLink far and away outperformed every other unit we tested. That's why it won our Editor's Choice award. Even without many of the features offered by some of its competitors, including the ability to do point-to-multipoint bridging or IP routing, its simple setup and impressive performance put it on top. RadioLAN's product consistently yielded wireless transfer rates of 6.5 Mbps to 7 Mbps, second only to Western Multiplex's Tsunami. The BridgeLink's next-closest competitor, Cisco's AIR-BR340, gave us an average transfer rate of 5.5 Mbps. The BridgeLink's software also let us do some packet-filtering by protocol (IP, IPX, NetBEUI and NetBIOS), and provided options to regulate packets that were either accepted or denied by MAC (Media Access Control) address.

The BridgeLink is unique in its design, looking nothing like any of the other products we saw. Each bridge consists of two small units: The first has an RJ-45 jack to connect to the network and an RJ-11 serial connection for configuration. The box has an interface that connects to the second unit, which has only an N-type connector to go out to the antenna. The antennas that RadioLAN ships with the device have a range of only one mile, which is on the lower end of the distance ranges we saw, especially in contrast to BreezeCom's BreezeNet. BreezeCom's product can send packets over distances of up to 15 miles without amplification. We spoke to several users who claimed the BridgeLink can go as far as 30 miles using higher-range antennas and amplification devices, but we were unable to test these assertions.

The BridgeLink's setup gave us no trouble at all. The first step is to run a utility that finds all the bridges connected on the network and lets the user assign an IP address to each. Once this is done, the program loads the user's default Web browser and connects to the bridge. The Web interface let us configure all the options we needed on both bridges, including a Java applet that assisted with antenna aiming. The software lets the administrator monitor bridge information, including status and signal strength. The product also has SNMP support for configuration. The BridgeLink implements RadioLAN's 10BaseRadio technology, and is unique in that Differential Pulse Position Modulation is used as the communication protocol. The bridge also uses narrow-band microwave transmission. While this partially explains the high throughput results we saw, it's also one of the reasons the BridgeLink has limited range out of the box; the only way to combat the distance issue is to use amplification devices. The BridgeLink is also the only product to operate in the U-NII transmission band rather than the ISM band. U-NII does not allow the use of spread-spectrum devices, and therefore can handle more capacity, which improves the bandwidth. However, distance suffers without the use of a spreading method.

Certainly the Campus BridgeLink's lack of options is a disadvantage. However, the product's strong performance, simple yet intuitive interface and solid design makes it a good choice for many sites.

Wireless Campus BridgeLink Model 347, $2,999, RadioLAN, (888) 2RADIOLAN, (408) 616-6300; fax (408) 524-0600. www.radiolan.com or sales@radiolan.com

Western Multiplex 12-Mbps Tsunami 5.8 GHz 10BaseT

Western Multiplex, which developed the original spread-spectrum T1 product in 1992, is no stranger to the wireless market. We tested its 12-Mbps Tsunami wireless Ethernet bridge operating at 5.8 GHz in the ISM band, as well as its 45-Mbps version operating at 5.8 GHz in the U-NII band (see "Wireless Bridging Beyond 12 Mbps"). Western Multiplex also had the only true full-duplex 12-Mbps radio among our tested products, with the ability to transmit a total of 24 Mbps over the air.

Western Multiplex's 12-Mbps wireless bridge turned out great data-throughput results, but the device lacks significant management options necessary for internetworking data devices. The product's operation is straightforward: Simply plug it into your network port and it begins transferring everything. There's no additional software and absolutely nothing to configure. Any options, such as choosing full- or half-duplex, are set by DIP switches in the back of the unit; that's not very attractive as far as manageability is concerned. Optional SNMP support does let you make this bridge manageable by integrating it with network-management software that can handle a TBOS bit stream.

Tsunami bridges are plug-and-play devices, so installation is very easy. We liked the option for an order-wire interface to allow intercom capabilities between units, and remote-monitoring front-end display via front-panel controls. Data throughput was by far the best of the nine products we tested: We found it to be the most consistent, without any fluctuation in the signal. The bridge also has T1 DSX-1 capability, which lets it transmit a T1 channel over the air.

12-Mbps Tsunami 5.8 GHz 10BaseT, $6,995, Western Multiplex, (800) 258-8383, (408) 542-5200; fax (408) 542-5300. www.wmux.com (Western Multiplex has been acquired by Proxim Corporation)

Cisco Systems Aironet 340 11-Mbps DSSS Bridge

Cisco's Aironet 340 Series AIR-BR340 came in third, held back somewhat by its performance and options. One of the dominant players in the indoor wireless-LAN market, Cisco has stated that the AIR-BR340 will let it compete in the outdoor market as well. (Cisco completed its purchase of Aironet Wireless Communications in March.) Using a design and interface similar to the company's indoor line, the AIR-BR340 made a solid showing. We had to use a serial connection to set up the bridge. Once an IP address is assigned to each bridge via the serial link, a telnet session or Web browser can be used to access the additional features. But navigation through both the telnet and Web interfaces wasn't easy, and it took us some time to learn our way around the different screens.

The AIR-BR340 has one of the most thorough sets of configuration options we saw. Affording the ability to configure nearly every aspect of your radio connection, Cisco crams a lot into its setup programs. Compared with the RadioLAN BridgeLink's Web interface or Lucent's software for its Orinoco WavePoint II, however, Cisco falls behind in usability. We question how much of what Cisco lets you modify is really necessary. With a raw data rate of 11 Mbps, the AIR-BR340 demonstrated reasonably strong results during throughput testing, operating at significantly faster speeds when transferring large amounts of data (averaging 5.5 Mbps) as opposed to smaller burst segments (averaging 4.8 Mbps). The AIR-BR340 supports point-to-multipoint applications, providing a maximum of three simultaneous channels. The AIR-BR340 also did well when it came to range: It was in the upper third of the tested products, beating the entrants from Lucent, Pinnacle and Wave Wireless handily. Cisco claims the product can cover eight miles using the right antenna configuration, and that assertion proved credible in our tests. The AIR-BR340 was the only device we tested that uses an RP-TNC interface for antenna connections. The vendor also provides a wide variety of antenna options, from directional Yagi and dish antennas to omnidirectional point-to-multipoint solutions that connect to the TNC interface.

Aironet 340 Series AIR-BR340 11-Mbps DSSS Bridge, $1,899, Cisco Systems, (800) 553-6387; fax (408) 526-4100. www.cisco.com