How To Determine The Integrity of an Ethernet Line Design Team 7 Mark Jones Sedat Gur Ahmed Alsinan Brian Schulte Andy Christopherson

Introduction  Ethernet History and Structure  Time Domain Reflectometry  Active Link Cable Diagnostics  Digital Spectrum Analysis  Power-over-Ethernet Detect  Output Data

History of Ethernet  Computer based networking technology for Local Area Networks (LANs)  Developed by Xerox in Early 70’s  Used for approximately 85% of world’s LAN-connected PCs and workstations  Implemented with multiple types of cable  Coaxial  Twisted Pair  Fiber Optic

Twisted Pair Wires  Used in many Ethernet and telephone systems  Receiver takes the difference between the wire pair  Any interference in signal will be canceled out  Advantages  Cables are thin, easy to run throughout building  Flexible  Cheap to manufacture  Disadvantages  Resistance to electromagnetic interference depends on pair twisting scheme used

Twisted Pair Standards  Category 3  Up to 10 Mbps  Bandwidth up to 16 MHz  Popular in early 90’s  Category 5  Used for mainly 100Mbps networks  Bandwidth up to 100Mhz  Category 5e  Enhanced version of Category 5  More rigorous standards  Recommended for most networks  Category 6  Bandwidth up to 250MHz  Recommended for gigabit speeds

So what kind of errors are we looking for?  Opens and Shorts  Cable impedance mismatch  Bad connectors  Terminations mismatches  Water damage  Any other discontinuities  Also can find cable length

Time Domain Reflectometry  Will diagnose opens, shorts, cable impedance mismatch, bad connectors, termination mismatches, etc.  Uses reflections to find these errors and their locations

Time Domain Reflectometry  Pulse is transmitted of known amplitude down twisted pairs  Reflects off imperfections and faults  Measure return time and amplitude of reflections

Time Domain Reflectometry  With the gathered data we can find  Distance and Magnitude (Impedance)  Non-terminated Cables (Opens and Shorts)  Discontinuities (Bad Connectors)  Improperly Terminated Cables

Time Domain Reflectometry

Active Link Cable Diagnostics  Use of passive digital signal processing  Will find cable length with active cable  Uses predefined parameters based on the cable properties  High accuracy cable length

Spectrum Analysis  Analog Spectrum Analysis  Uses a variable band-pass filter  Digital Spectrum Analysis  Uses Discrete Fourier Transform  Results in frequency spectrum of our signal

Digital Spectrum Analysis  Gives magnitude of the frequency response  This will show us how the signal is spread out along the frequency spectrum  Allow us to see noise along the line  Especially how it relates to the length of the cable

Power-over-Ethernet Detect  Power can run over 2 pairs of wires while data is on the remaining 2 pairs  Power is supplied by a PSE and received by the PD.  42~57 Volts

Power-over-Ethernet Detect  Detection Level can be varied as well as Turn-on and Turn-off voltages

PHY to MAC Communication  PHY Layer  Transmission of raw bits, not logical data  MAC Layer  Logical communication

PHY to MAC Communication  Microcontroller (MCU)  Able to communicate with PHY layer  Uses Media Independent Interface (MII)

Readable Interface  Microcontroller can be programmed to send data to  LCD Display  Computer  LEDs

PHY to YOU

Conclusion  Ethernet History and Structure  Time Domain Reflectometry  Active Link Cable Diagnostics  Digital Spectrum Analysis  Power-over-Ethernet Detect  Output Data  QUESTIONS?