![]() ![]() Link Fault Pass-through operation with a single media converter The fact that this is not happening can lead to network failure.įig 4. Due to this reason, the switch will continue transferring data to the media converter assuming data to be transmitted to the switch on the left. The problem is that the switch will not understand an LFP message and, so, it will be dismissed. If the connection over a copper cable between the left switch and the media converter gets disrupted, the media converter sends a message to the right switch saying that the transfer has been unsuccessful. Firstly, one should keep in mind that LFP is a function that is implemented within a media converter. Actuality, it is easy to realize why application of LFP function causes problems in this situation. Let us consider what will happen if only one converter with LFP function is used (see fig. Moreover, one manufacturer may use different microchips in various models that will lead to interoperability between various models. This follows from the fact that various manufacturers may use proprietary protocols for “Far End Fault” and “Link Fault Pass Through” functions. Not only media converters must be applied in pairs, they must come from one manufacturer and belong to one model, preferably. The problem of using only one converter lies in the fact that, if activated, “Far End Fault” or “Link Fault Pass Through” function will not work properly. Many design engineers ignore this condition and use only one Ethernet-to-Fiber converter. The illustrations above show that media converters are used in pairs. Please note: use media converters in pairs Figure 5: Converter A switches off copper cable connection.Figure 4: Converter B switches off the second optic fiber cable core going to converter A.Figure 3: Converter B switches off copper communication.Figure 2: One of optic fiber cable cores going from converter A to converter B gets broken.Figure 1: Normal operation of two media converters.The detailed operation of FEF is given in fig. Here is where the Far End Fault function comes in. However, if another optic fiber cable core is still safe, the switch on the right will continue transferring data to the switch on the left, which can lead to transmission errors within the whole network. ![]() In this case, the left converter will not be able to transfer data to the right converter. Let us consider, what will happen, if one of the optic fiber cable cores connecting the media converter on the left with the one on the right breaks. 2 Link Fault Pass-through in operationįar End Fault (FEF 802.3u) – function serves to notify on a breakdown of one of the optic fiber cable cores (!). For that reason, there appeared such functions as “Link Fault Pass-through” and “Far End Fault”.įig. ![]() That may sound rather simple, however, when used together, such “cable” actually comprises two copper cables and two fiber optic cables (see Fig. Basically, a media converter must “simulate” a cable. The converter must remain invisible to network devices. Needless to say, that the basic role of a media converter lies in data transfer between two devices that can’t be connected to each other directly. This is true, however, modern media converters also support the functions that, if applied correctly, can enhance network reliability. One might think, that the sole purpose of a media converter is to convert a signal from one transfer medium (copper wire) to the other (optical fiber). This article includes recommendations on application and choosing media converters, operation principles of “Link Fault Pass-through” and “Far End Fault” functions, as well as converters behaviour in redundant networks. Meanwhile, they have their own application specifics that must be considered when building a network. Ethernet -over-Copper to Fiber converters (media converters) are rather simple devices with no complex additional settings. ![]()
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