How To Determine The Integrity of an Ethernet Line

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

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

3. 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

4. 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

5. 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

6. 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

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

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

9. 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

10. Time Domain Reflectometry

11. 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

12. 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

13. 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

14. 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

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

16. PHY to MAC Communication • PHY Layer • Transmission of raw bits, not logical data • MAC Layer • Logical communication

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

18. Readable Interface • Microcontroller can be programmed to send data to • LCD Display • Computer • LEDs

19. PHY to YOU

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