Optical Taps are passive devices that enable one to monitor Optical fiber links to identify faults & help trouble shoot an Optical network. They are generally placed in-line (in-between) the two devices that are connected with an optical fiber cable. Let us learn more about Optical Taps, in this article.
An Optical tap is a passive device that can split an optical signal into two identical data streams using a prism. One of these streams is passed through the network in its normal route, and the other is sent to an analyzer/ monitoring station for monitoring the data passing through a Fiber cable. So, if you want to continuously monitor the data flow between a SAN Network and the Optical Fiber Switches that are connected using Fiber Cables (for example), you can use an Optical Tap /Fiber Splitter to do so.
Generally, the Optical tap is connected in-line. That is, the Fiber cable from the Optical switch terminates on the splitter and from the splitter two fiber cables go to the Network destination (like SAN/ Server/ Another Optical Switch, etc) and Monitoring device respectively, as shown in the first diagram. The optical signal is split into a ratio of 50:50 to 80:20 (Network Destination : Monitoring Device), depending on the type of optical splitter used.
There are two types of Optical Taps/ Splitters. Single Channel splitters take one input and give two output signals (as shown in the first diagram) & Multi Channel splitters accept multiple inputs and connect to multiple outputs (as shown in the second diagram).
Optical Taps are mainly used to give network visibility, which makes trouble-shooting of networks easier. Copper Taps provide a very similar function like Optical taps (In copper networks using Cat 5/6 Cables) but they duplicate the data using electronic circuitry, instead of using a prism.
Advantages of Optical Taps:
- Optical taps are passive devices and hence they don’t need any power supply.
- The monitoring station/ network analyzer receives an exact out-of-band copy of the data stream traveling through the optical cable.
- The data stream that is flowing through the cable is not affected due to an Optical splitter.
- Optical taps do not induce any latency of its own.
- One can use a span port (on the Optical switch) to monitor the Optical ports, but the capacity of the analyzer is limited to the speed of the span port. In a heavily used network excess traffic (beyond its capacity) is dropped by the span port. Since Optical taps use individual splitters for each cable, there is no dropping of packets.
- Optical taps are useful for monitoring a Fiber Channel based SAN without interrupting the data flow.
- Optical taps can operate in multiple line speeds – 100 Mbps, 1 GE & 10 GE.
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