A communication network comprising: communication media; and a plurality of network nodes (120, 122, 124, 126, 128, 130, 132, 134) coupled by said communication media, each of said plurality of network nodes comprising a first communication channel and a second communication channel, said first communication channel comprising a first physical layer transceiver, PHY device, said second communication channel comprising a second PHY device, said plurality of network nodes coupled in a dual-redundant Ethernet ring topology, characterized in that each of said plurality of network nodes comprises: multiple-levels of loop-back test hardware; wherein said multiple-levels of loop-back test hardware comprise: Media Access Controller, MAC, loop-back hardware (230, 234) configured to route outgoing data packets to MAC inputs to facilitate detecting MAC failures; and PHY loop-back hardware (242, 248) configured to connect a receiver output of said PHY device and a transmitter input of said PHY device to facilitate detecting PHY device failures, wherein said first communication channel further comprises a first Ethernet controller and a Media Access Controller, MAC, said second communication channel further comprises a second Ethernet controller and a MAC. communication media; and a plurality of network nodes (120, 122, 124, 126, 128, 130, 132, 134) coupled by said communication media, each of said plurality of network nodes comprising a first communication channel and a second communication channel, said first communication channel comprising a first physical layer transceiver, PHY device, said second communication channel comprising a second PHY device, said plurality of network nodes coupled in a dual-redundant Ethernet ring topology, characterized in that each of said plurality of network nodes comprises: multiple-levels of loop-back test hardware; wherein said multiple-levels of loop-back test hardware comprise: Media Access Controller, MAC, loop-back hardware (230, 234) configured to route outgoing data packets to MAC inputs to facilitate detecting MAC failures; and PHY loop-back hardware (242, 248) configured to connect a receiver output of said PHY device and a transmitter input of said PHY device to facilitate detecting PHY device failures, wherein said first communication channel further comprises a first Ethernet controller and a Media Access Controller, MAC, said second communication channel further comprises a second Ethernet controller and a MAC. multiple-levels of loop-back test hardware; wherein said multiple-levels of loop-back test hardware comprise: Media Access Controller, MAC, loop-back hardware (230, 234) configured to route outgoing data packets to MAC inputs to facilitate detecting MAC failures; and PHY loop-back hardware (242, 248) configured to connect a receiver output of said PHY device and a transmitter input of said PHY device to facilitate detecting PHY device failures, wherein said first communication channel further comprises a first Ethernet controller and a Media Access Controller, MAC, said second communication channel further comprises a second Ethernet controller and a MAC. Media Access Controller, MAC, loop-back hardware (230, 234) configured to route outgoing data packets to MAC inputs to facilitate detecting MAC failures; and PHY loop-back hardware (242, 248) configured to connect a receiver output of said PHY device and a transmitter input of said PHY device to facilitate detecting PHY device failures, wherein said first communication channel further comprises a first Ethernet controller and a Media Access Controller, MAC, said second communication channel further comprises a second Ethernet controller and a MAC.