#583 Payload for network cable testing

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opened 1 month ago by swiftgeek · 0 comments

Turns out most PHYs support cable testing (TDR/frequency response)

  • Marvell (VCT - Virtual Cable Tester)
  • Atheros/Qcom (CDT - Cable Diagnostics Test)
  • Intel (TDR, channel frequency response)
  • Broadcom (Cable Diagnostic Mode)
  • Micrel (now Microchip) (LinkMD Cable Diagnostic)
  • Realtek (UTP cable tester / RTCT - RealTek Cable Testing) (very uncommon for NIC/PHY to have it, so far it's only limited to switches with R(G)MII interface(s))
  • Universal method - remote fault (will only indicate whether issue with cable exists, could be only useful when RJ45 lacks LEDs)

They have relatively simple interface so most likely UI will take 90% of code, 9% result interpretation, and 1% for chip specific code

This will come handy when loading OS over network without any other storage attached than flash on motherboard

Interface mockups welcome (on libpayload, so curses kind)

Some ideas:

  • Color selection for pairs according to T568A/T568B/none
  • Color selection for both ends (for crossover cables, but that should be rare nowadays due to Auto MDI-X)
  • Selecting between what pairs are used in a cable (to support 100mbit connection)
  • Graphing results for all channels over time
Turns out most PHYs support cable testing (TDR/frequency response) * Marvell (VCT - Virtual Cable Tester) * Atheros/Qcom (CDT - Cable Diagnostics Test) * Intel (TDR, channel frequency response) * Broadcom (Cable Diagnostic Mode) * Micrel (now Microchip) (LinkMD Cable Diagnostic) * Realtek (UTP cable tester / RTCT - RealTek Cable Testing) (very uncommon for NIC/PHY to have it, so far it's only limited to switches with R(G)MII interface(s)) * https://elixir.bootlin.com/linux/latest/source/drivers/net/ethernet/realtek/r8169.c (RTL_GIGA_MAC_VER_35, RTL_GIGA_MAC_VER_38) * Universal method - remote fault (will only indicate whether issue with cable exists, could be only useful when RJ45 lacks LEDs) They have relatively simple interface so most likely UI will take 90% of code, 9% result interpretation, and 1% for chip specific code This will come handy when loading OS over network without any other storage attached than flash on motherboard Interface mockups welcome (on libpayload, so curses kind) Some ideas: * Color selection for pairs according to T568A/T568B/none * Color selection for both ends (for crossover cables, but that should be rare nowadays due to Auto MDI-X) * Selecting between what pairs are used in a cable (to support 100mbit connection) * Graphing results for all channels over time
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