I am dedicating this article to an experience I had with connecting switches using 10/100 Base-T 100Base-FX fiber converters (Transceivers).
It is a pain when the transceivers goes bad especially if it is not identified as causing packet loss or slow link connection on the switched network.
I had an experience were a location was complaining of having slow connection to the server resources and the IP phones were having poor call quality. When the user is on a call, the caller will hear the person very clearly but the other user would constantly hear drop in the conversation.
When a ping test was done, for every 5 or 10 ping response, the packet will drop, even to the uplink switch. When a ping test is done to the same switch, it was successful with no packet loss.
Looking at the interfaces status, there was no indication of any CRC errors or other parameters such as runts or interface reset indicating no problem with cable.
I connected my laptop directly to the transceiver and did a ping test and the same result. This is where I concluded that the problem was with the transceiver; low and behold when I swap out the transceiver for the direct fiber connection to the switches, all connection issues just disappear.
Conclusion: Avoid using transceivers to connect switches over fiber links, as much as possible use SFP modules because when the transceivers goes bad, they cause latency to the connected location. Also I have noticed that the devices are very unreliable and are fragile hence they are high maintenance and a waste of time, effort and money which most of us Engineers don’t have time to waste.
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