4/7/2023 0 Comments Rapidlink inc linkedin![]() ![]() A backup path, such as an 802.11b RF link, may be required for mission-critical applications to maintain connectivity during low-visibility periods. The rule of thumb seems to be that below 50-percent visibility, the optical link will suffer. Rain did not bother the link, but fog caused some problems. Link status and throughput tests were then conducted anew, with identical results to the previous tests. I placed one transceiver out in the elements, linked to the other through a window. Due to the 300-foot distance limit on copper, this may not be possible in some installation scenarios.Īfter the tests in the lab, it was time to head outside. Unfortunately, as the port is 10Base-T, a copper run must be made to the transceiver location. SNMP data is provided by the management port, permitting the transceivers to be integrated into most network management systems. The rear panel includes a DB9 serial console connector, a 10Base-T management port, an SX or LX SC fiber port, and a rich set of status indicators, including separate lights for fiber and optical links, as well as an LED optical signal strength meter. But even the karate-chop movement of a hand through the light path is enough to trigger packet loss.Įach transceiver has an array of management options. When cutting straight through the air, the link is quite stable. Another test included flood pinging between the servers on either side of the transceivers and measuring the packet loss created by interruptions in the light path. I measured raw TCP throughput at a consistent 920Mbps. For all intents and purposes, the link performed like a gigabit fiber link. I also ran raw TCP and UDP (User Datagram Protocol) throughput tests using wildly different packet and window sizes. Tunable parameters within the DT-130, such as a configurable hold-down timer, can also be used to prevent rapid link flapping.Īfter setup, I pushed billions of packets through the DT-130s. Integrating switching and 802.1q trunking capabilities would remove the need for the separate copper management interface and provide fiber link stabilization. In a layer-3 switching environment, spanning-tree will have similar problems. ![]() For example, should OSPF or another routing protocol be running across the link, twitches to the optical link could cause frequent route recalculations and increased load on the routers and switches. ![]() This shortcoming means that fluctuating optical links could cause deeper network problems. Until an optical link is achieved, the fiber remains dark. When fiber is run from a switch to a transceiver and the transceiver is powered on, no link is established. One unfortunate facet of the DT-130s is its layer-1 characteristics. The farther away the other transceiver, the better the tracking works. I also found that active tracking works well when the motion is smooth and steady rough motion will cause link failure. In practice, I found operation to be quite binary: either there is a link, or there isn’t signal strength does not necessarily affect throughput. Using their integrated scopes, I was able to quickly aim each unit and establish a link between them. In the lab, I set up the DT-130s about 30 feet apart, running from the SC-SX multimode fiber port of each transceiver to a single layer-3 switch. The DT-130s also boast active tracking that can sustain a link even if the transceivers move slightly, such as when mounted atop two swaying skyscrapers. Using free space optics, a pair of Canobeam DT-130 transceivers is able to securely pump data via a beam of light at gigabit speeds across distances of as far as 0.75 miles. Canon’s Canobeam optical transceivers take the RF out of wireless networking, overcoming many of Wi-Fi’s limitations. Then again, distance, bandwidth, or security requirements may rule out Wi-Fi. In places where fiber can’t reach, whether due to physical or economical constraints, you might resort to an 802.11a, b, or g link. ![]()
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