Transcript Gigabit Ethernet

Gigabit Ethernet
Group 1
Harsh Sopory
Kaushik Narayanan
Nafeez Bin Taher
Background Information
An introduction to Gigabit Ethernet
What Is Ethernet?
Most successful LAN technology
 Operates at the Data Link Layer (layer 2) of
the OSI reference model
 Acts as an interface between the MAC layer
and transceivers in Ethernet hardware
(Physical layer)
 Uses contention based medium access
protocol – CSMA/CD

Gigabit Ethernet

Builds on top of the Ethernet protocol

Allows data transfer speeds of 1000 Mbps

Provides reliable communication between
applications of the Network and Transport
layers
IEEE 802.3 Gigabit Ethernet
Specifications
802.3z



1000BASE-CX (shorthaul copper)
1000BASE-LX (longwavelength optics)
1000BASE-SX (shortwavelength optics)
802.3ab


1000BASE-T (twisted
pair)
1000BASE-LH (longhaul)
Benefits of Gigabit Ethernet

Higher data transfer rates

Builds on current Ethernet

Familiar technology

Minimal staff training
Project Proposal
Our aim and immediate goals
Project Aim

Main Issue: High costs associated with
installing Gigabit Ethernet technology

A source of high cost: Opto-electronic
transceiver module

Project Aim: Design cheaper module
Immediate Goals

Set up test bed for future use

Test module on evaluation board to confirm
Gigabit transfer rates

Test module with Gigabit Ethernet card to
confirm successful data transfer
Brief Description of Module
Agilent HFBR 53D5
 Consists of transmitter and receiver sections
 Transmitter section consists of an 850 nm
VCSEL in an Optical Sub Assembly (OSA)
 Receiver consists of a Si PIN diode
mounted on the OSA with a transimpedance
preamplifier IC
 Signal Detect circuitry provided

Design Steps and Considerations
Our design approach
Design Steps
Construct Evaluation Board
 Remove Transceiver from card
 Place components and Transceiver on Board
 Test Board
 Connect Board to Gigabit Card
 Test setup with another Gigabit Card

Agilent Schematic

The evaluation board that Agilent provides
for testing the module is schematically
represented below
Georgia Tech Evaluation Board

In order to reduce costs, a GA Tech
evaluation board was used and is shown
below
Circuit Schematic

All parts from the Agilent design were not
necessary and the circuit layout used is
shown below
Primary Design Considerations

Power Supply Filtering Circuit

Transmission Lines and Terminations
Power Supply Filtering Circuit

Agilent Board: Circuit was included to keep
both parts of the transceiver independent of
their power supply considerations

Our Board: Eliminated the need for the
circuit by having two separate power
supplies for both parts of the module
Transmission Lines and
Terminations

Transmission lines were eliminated from
our boards
– Care was taken to keep the length of the lines
less than 1/10th the signal wavelength i.e. 6 cm
– Sharp angles on the board were avoided
Miscellaneous Considerations

Reduce susceptibility to noise
– Accomplished by using differential inputs as
opposed to single-ended ones

Top and bottom of board unconnected
– Used vias to connect the two
Component Details

Capacitors mainly used for Decoupling
– Capacitors used to separate power supplies
from circuit.
– Protect circuits from transients

Resistors used for terminations and biasing
Problems Faced

Soldering
– surface mount components

Top and Bottom of board unconnected
– Power not getting through from one side to
another
– Solved by allowing solder to drip through to
form a connection
Connecting Card to Board
Used RG174 Cable with SMA connectors to
connect card to board
 Removed resistor networks from Gigabit
card
 Used wire to connect signal detect pin from
board to card
 Connected the grounds of board and card
with wire

Test Layout
Resistor networks removed
Results
Eye diagrams and bit error rate data
Board Test Setup
Power
Ch1
Oscilloscope
Ch2
Oscilloscope
RX
RX
Fiber Optic Cable
TX
Pattern
Generator
TX
Pattern
Generator
Eye diagram for 10m Cable
Eye diagram for 100m Cable
Significance of Eye Diagram
Eye formed by superimposition of
pseudorandom bit patterns
 Eye generated met standard specifications

– Indicated signal quality was acceptable
Standard Eye Mask
Superimposed Eye Mask
Bit Error Rate Data

10m cable: No errors encountered

100m cable: No errors encountered

Errors appeared when using PN23 encoding
scheme at 1.2 Gbps
– Error rate = 2.3 errors/Mb
Verification of results
Card was plugged into computer
 Passed loop-back diagnostic test
 Connected to another computer using fiber
optic cable
 Packets sent and received with no errors
 File transferred successfully over link

Computers on LAN
Summary
The card was assembled and tested
successfully
 Questions?

– Harsh Sopory (gte648h)
– Kaushik Narayanan (gte678h)
– Nafeez Bin Taher (gte078h)