applied data networking © 2003, hans kruse and shawn ostermann itl basics of encoding and wiring

Applied Data Networking© 2003, Hans Kruse and Shawn Ostermann

ITLBasics of Encoding and Wiring


Objectives

Quick overview of wide-area communications

Define the term “Structured Wiring” Define "analog" and "digital" data. List the common methods used to

encode analog/digital data using analog/digital signaling.

Discuss transmission media and wiring system standards


Wide-Area Data Communication Nomenclature

DTE DCE

Wide Area Network

Short-Distance Connection

Data Consumer or Local Area Network

Router

Workstation

Server/Mainframe

RS-232

V.35 RS449/530

HSSI

Modem

CSU/DSU

DS-0

ISDN

DS-1 DS3

OC1 OC3 OC12


RS232-C Connections

DTE DCE

Protective Ground

TD (Transmit Data)

RD (Receive Data)

RTS (Request to Send)

CTS (Clear to Send)

DSR (Data Set Ready)

Signal Ground

CD (Carrier Detect)

RD (Ring Detect)

DTR (Data Terminal Ready)


Transmission Media

Guided Media– Twisted Pair– Coaxial Cable– Optical Fiber

Unguided Media– “Broadcast”-type radio

transmission» Wireless LANs, Cell Phones, PCS

– Satellite– Point-to-Point Microwave


Transmission Systems

Basic multiplexing– DS-n (T1, DS3)– SONET (OC-3, OC-12, etc)– WDM

Multiplexing and Other Functions– Ethernet– Frame Relay– ATM


Structured Wiring

Main Cross-Connect (Main Distribution Frame)– Riser Cable(“Backbone”)

Intermediate Cross-Connect (Int. Dist. Frame)– Horizontal Wiring

Jack Field– Drop Cable

Workstation


Why use Hierarchical Wiring?

Flexibility = Lower CostFrom Bates, Voice and Data Communications Handbook:

– Estimated Cost for 50 single wire pulls:$15,568

– Estimated Cost for 50 dual wire pulls:$16,935


Wiring Standards

Building Wiring Standards– Electronic Industries Association– Telecommunications Industry

Association– EIA/TIA 568 Commercial Building

Wiring Standard “Outside Plant”

– Bell Labs technical publications– Now maintained by Telcordia

(formerly Bellcore)


RJ-What?

As an aside for the eternally curious:

The RJxx nomenclature appears in the legal documents used by the FCC to identify permitted methods to connect telecom equipment to the network

For the really, really curious:

Title 47 CFR, Part 68, Subpart F, Section 502


Signal Transmission Overview

Analog Data

over

Analog Transmission Systems

Digital Data

over

Analog Transmission Systems

Analog Data

over

Digital Transmission Systems

Digital Data

over

Digital Transmission Systems


Analog Signaling of Digital Data

Encode "0" and "1" as changes in one signal property

Amplitude Shift Keying: Use two signal amplitudes, one for each bit value.

Frequency Shift Keying: Change the signal frequency to indicate the bit value.

Phase Shift Keying: Create a phase change relative to the most recent bit to indicate the bit value


Digital Signaling of Analog Information

Voice Codec– Pulse Code Modulation (PCM)– Compressed Voice

Video Codec


Digital Encoding ExamplePCM

Example: Voice 4000 Hz Sample at twice the highest frequency

(8000 samples per second) 8 bits per sample Result: 64kbps


Digital SignalingDigital Data

Encoding Schemes: NRZ Manchester Differential Manchester Bipolar - AMI


Digital Signaling of Digital Data

Manchester Code

1 10 1 0

Every bit position has a transition (clocking)Signal has no DC componentTransition Direction Encodes the DataUsed in Ethernet


Bipolar AMI Coding

1 1 1 10 0

Used in T1 Signaling


Levels (Wiring) and Categories (System Performance)

Level/CAT 1 1Mbps

Level/ CAT 2 4Mbps

Level/ CAT 3 16Mbps

Level/ CAT 4 20Mbps

Level/ CAT 5 100Mbps1000 Mbps (4 pair)

100m max distance

Level/ CAT 5E 100Mbps1000 Mbps (4 pair)

Level/ CAT 6 200-250MHz Not yet a standard


Cable standards versus system performance

Source: http://telecom.copper.org/networking.html


Applications

Source: Lucent Technologies


Ethernet

Designed as a broadcast medium; each transmission is received by every station

Based on a bus architecture Manchester Encoding Several Media Types

– 10Base5– 10Base2– 10Base-T– 10Base-F


10Base-T

Simulates the Ethernet bus using an active star topology.

Uses unshielded twisted pair wiring. “4-pair” (8 conductor) wiring is

normally used, but only 2 pairs are used – 1 transmit pair one receive pair

Each station connects to a central hub.– Cables are wired “straight through”– Hub ports are “crossed”

(transmit/receive are reversed


Fast Ethernet

All use a star topology 100Base-TX

– Two pair copper wire (Cat 5)– Same pin-out at 10Base-T, better wire

100Base-FX– Two fibers

100Base-T4– Rarely used; 4 pair lower quality (cat 3)

wires 1000Base-X (4 pair Cat 5 or 5E)


FDDI

100 Mbps Ring Usually based on optical fiber Based on the Token Ring Standard Provides capacity pre-allocation Economics:

– Ethernet is cheaper than token ring and does almost as good a job – so it wins

– Fast Ethernet is cheaper than FDDI and does almost as good a job – so it wins


Other Stuff

The slides after this one have probably not been used in class unless a specific question came up


Phase and Amplitude Shift KeyingExample: Eight Levels

000

011

001

100

010

101

110

111

90 degreesnormal amplitude

180 degreesdouble amplitude



NRZ-L coding (Non-Return to Zero, Level)

1 10 1 0

Multiple bits may be sent without a transitionSignal has a DC componentExample: RS-232 uses +3V for "0" and -3V for

"1"



NRZI coding (Invert on One)

1 10 1 0

Multiple bits may be sent without a transitionSignal has a DC componentPolarity insensitive, partially self-timingExample: ISDN



Differential Manchester Code

1 10 1 0

Every bit position has a transition (clocking)

Signal has no DC component and is polarity - neutral

Differential Signal provides some error detection

applied data networking © 2003, hans kruse and shawn ostermann itl basics of encoding and wiring

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