Many times I've come across that there is an "X" added to the end of network-related names on equipment, like how copper cables have wires in them called TX and RX, and ports on switches can have names like "100BASE-FX". Why is the X there? Does it mean anything?

  • I thought we already resolved this question for Rx and Tx
    – This
    Mar 25 '14 at 16:24
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin
    Aug 8 '17 at 16:25

Source: Ethernet_Nomenclature_GA-TB-357.pdf


Optical link that uses short wavelength (850 nm) lasers over two FDDI grade multimode optical Fibers, with eXternal sourced coding. Supports up to at least 2 km.

So, F=fiber, X=external sourced coding

  • 1
    Allright, but what does "external sourced coding" mean :P? Mar 25 '14 at 16:15
  • 1
    Did you try searching for this term in the pdf I linked? Page 5, under "Fast Ethernet (100Mbps)"
    – mulaz
    Mar 25 '14 at 16:23

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