May 8, 2000
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Wireless Bridging Beyond 12 Mbps
By Michael J. Utell and Asad Irshad
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our situation: You have hundreds of nodes, simultaneous voice and data capabilities, or bandwidth-hungry applications. You may also need a backup to your wired buildings. If your business requires more than 12 Mbps of data throughput, help may be at hand: We evaluated two high-performance wireless bridges: the Proxim Stratum 100 and the Western Multiplex Tsunami 5.8 GHz 100Base-T, operating at 100 Mbps and 45 Mbps (full-duplex), respectively.If there were just one word to describe the Stratum 100, it would be impressive. It pushes unlicensed wireless technology to its limits. Transmitting at 100 Mbps, full-duplex, with two T1 DSX-1 channels simultaneously, Proxim's device definitely commanded our attention. The Stratum 100 uses the U-NII band for high-speed data throughput and offers Simple Network Management Protocol management features.
Setting up the Stratum 100 bridge was relatively painless, though not quite as straightforward as with the 10-Mbps to 12-Mbps products we tested. The radio is mounted on the antenna, and fiber is run from the bridge to the antenna and the radio. The radio gets DC power from the bridge via a copper cable. The bridge unit also has two DSX-1 interfaces to connect any T1 equipment directly. Common applications would be to connect to a PBX and have voice communication over 48 DS-0 channels instead of relying on voice over IP. The LEDs on the antenna make it easy to position and align. All these features come at a steep price, however: The Stratum 100 is $45,000 per link.
To get an idea of the Stratum 100's real-world throughput capability, we tested the device using Netcom Systems' SmartBits 200 network performance-analysis system; in our tests, we were able to achieve 98-Mbps throughput. We then attached TTC's Fireberd 6000A T1 test equipment to the Stratum 100. The Fireberd flooded the T1 channels, and we used the SmartBits to perform data-throughput tests. We got the same 98-Mbps data throughput with dual T1 channels with a zero error rate. The dual T1 DSX-1 channels had no effect on LAN performance.
We liked the Stratum 100's performance and features; this product will serve you well if your needs call for high-end networking over the air. It's priced at $45,000 per link, which consists of two bridges.
The Tsunami 100Base-T wireless bridge will deliver rock-solid performance-it proved extremely reliable in our tests. It operates in the U-NII band (5.725 to 5.825 GHz) and has data interfaces for 10Base-T, 100Base-T, and 100Base-FX. It also offers a wayside T1 channel for telecommunication applications. One of this bridge's most important features, lacking in its 10Base-T cousin, is its built-in management support.
We evaluated this Tsunami bridge by running Ganymede Software's Chariot network-testing system over the link and were very pleased with the results: We saw 38-Mbps throughput, on average, which is quite impressive if you take into account the wireless overhead and data gaps. The bridge produced consistent results, with extremely low fluctuations in data throughput.
A technologically advanced product, the Tsunami 5.8 GHz 100Base-T demonstrated stability and strong performance in our tests. While the bandwidth it offers is about half that of the Stratum 100, you can purchase it for $9,995-less than a quarter of the Stratum's price. It's a good choice if your throughput requirements are in line with its capabilities.
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