7.1

PROTOCOLPROTOCOL

RULES & PROCEDURESRULES & PROCEDURES

TO GOVERN TRANSMISSIONTO GOVERN TRANSMISSION

BETWEEN COMPONENTS BETWEEN COMPONENTS

IN A NETWORKIN A NETWORK

**

7.2

ANALOG SIGNALANALOG SIGNAL• CONTINUOUS WAVEFORMCONTINUOUS WAVEFORM

• PASSES THRU SYSTEMPASSES THRU SYSTEM

• VOICE COMMUNICATIONSVOICE COMMUNICATIONS

**

Telecommunications, Networks

7.3

DIGITAL SIGNALDIGITAL SIGNAL• DISCRETE WAVEFORMDISCRETE WAVEFORM• TWO DISCRETE STATES:TWO DISCRETE STATES:

– 1-BIT & 0-BIT– ON / OFF PULSE

• DATA COMMUNICATIONDATA COMMUNICATION• USES MODEM TO TRANSLATE ANALOG USES MODEM TO TRANSLATE ANALOG

TO DIGITAL, DIGITAL TO ANALOGTO DIGITAL, DIGITAL TO ANALOG

**

0010111010011101001010101110111100100010000101111010110100111010010010110010101101100

7.4

TELECOMMUNICATION TELECOMMUNICATION SYSTEM COMPONENTSSYSTEM COMPONENTS

• COMPUTERSCOMPUTERS• TERMINALS (Input / output devices)TERMINALS (Input / output devices)• COMMUNICATIONS CHANNELSCOMMUNICATIONS CHANNELS• PROCESSORS (Modems; multiplexers; PROCESSORS (Modems; multiplexers;

front-end processors)front-end processors)• COMMUNICATIONSCOMMUNICATIONS SOFTWARE SOFTWARE

**

7.5

COMMUNICATION COMMUNICATION CHANNELSCHANNELS

MEANS BY WHICH DATA ARE MEANS BY WHICH DATA ARE TRANSMITTED:TRANSMITTED:

• TWISTED WIRESTWISTED WIRES (Copper Wires)(Copper Wires) – phone – phone lineslines

• COAXIAL CABLE:COAXIAL CABLE: (Insulated Copper (Insulated Copper Wires) – Cable televisionWires) – Cable television

• FIBER-OPTIC CABLE – FIBER-OPTIC CABLE – high speed backbone, high speed backbone, thousands of strands of clear glass fiber (hair),thousands of strands of clear glass fiber (hair),

• MICROWAVE – MICROWAVE – TerrestrialTerrestrial oror SatelliteSatellite

**

7.6

• SUPER CLEAR GLASS STRANDSSUPER CLEAR GLASS STRANDS• FAST, LIGHT, DURABLEFAST, LIGHT, DURABLE• BILLIONS OF BITS PER SECOND, FULL BILLIONS OF BITS PER SECOND, FULL

DUPLEX (10Gbps)DUPLEX (10Gbps)• EXPENSIVE, HARDER TO INSTALLEXPENSIVE, HARDER TO INSTALL• OFTEN USED AS OFTEN USED AS BACKBONEBACKBONE OF OF

NETWORKSNETWORKS

**

FIBER OPTICSFIBER OPTICS

SIGNALSIGNAL LASERLASER CABLECABLE PHOTOPHOTODETECTORDETECTOR SIGNALSIGNAL

7.7

• TRANSMISSION SPEED:TRANSMISSION SPEED: Bits per Bits per Second (BPS) or BaudSecond (BPS) or Baud

• BANDWIDTH:BANDWIDTH: Capacity of Channel; Capacity of Channel; Difference between Highest & Lowest FrequenciesDifference between Highest & Lowest Frequencies

COMMUNICATIONS COMMUNICATIONS CHANNELSCHANNELS

BROADBAND – High speed

1.5Mbps connection1.5MB file8 seconds to transmit

7.8

BPS: BITS PER SECONDBPS: BITS PER SECONDKBPS: KILOBITS PER SECONDKBPS: KILOBITS PER SECONDMBPS: MEGABITS PER SECONDMBPS: MEGABITS PER SECONDGBPS: GIGABITS PER SECONDGBPS: GIGABITS PER SECOND

7.9

Internet Connection Choices

DeviceDevice Upstream Upstream SpeedSpeed

Downstream Downstream SpeedSpeed

Cost per monthCost per month

ModemModem 56Kbps56Kbps 56Kbps56Kbps $20$20

CableCable

(Coax)(Coax)

100Kbps to 100Kbps to 500Kbps500Kbps

1.5Mbps to 1.5Mbps to 5Mbps5Mbps

$40$40

DSLDSL

(Twisted pair)(Twisted pair)

90Kbps to 90Kbps to 640Kbps640Kbps

144Kbps to 144Kbps to 2.2Mbps2.2Mbps

$40-$100$40-$100

T1 leased lineT1 leased line

24 channels24 channels

1.544 Mbps1.544 Mbps 1.544Mbps1.544Mbps $1,100$1,100

T3 leased lineT3 leased line

672 channels672 channels

44.7Mbps44.7Mbps 44.7Mbps44.7Mbps $8,000$8,000

SatelliteSatellite 150Kbps150Kbps 300Kbps to 300Kbps to 900Kbps900Kbps

$70$70

7.10

OTHER SERVICES:OTHER SERVICES:• DIGITAL SUBSCRIBER LINE (DSL):DIGITAL SUBSCRIBER LINE (DSL):

enhancing capacity over copper telephone enhancing capacity over copper telephone lineslines

• CABLE MODEM:CABLE MODEM: modem for cable TV for modem for cable TV for high-speed access to Internethigh-speed access to Internet

• T1 LINE:T1 LINE: dedicated telephone connection, dedicated telephone connection, 24 channels @ 1.544 megabits per second24 channels @ 1.544 megabits per second

**

7.11

Internet Infrastructure

Internet backbone – made up of many large networks (NSP’s) which interconnectNetwork Service Providers – own internet backbone.Examples are UUNet, CerfNet, SprintNet, IBM, WCOMNAP (Network Access Point) – Where NSP’s connect.ISP’s (Internet Service Providers) – Local and regional delivery subnetworks

7.12

NAPNAP

NAP NAP

ISP ISPISP

ISP

ISP

ISP

ISPISP

ISP

ISP

Internet NetworkArchitecture

Backbone

RegionalISP

LocalISP

7.13

Circuit-Switched NetworksCircuit-Switched Networks

• Local and long distance telephone Local and long distance telephone companies were early models in the companies were early models in the 1950s1950s

• Single paths were created to connect Single paths were created to connect two parties together, called two parties together, called circuit circuit switchingswitching

7.14

Packet-Switched NetworksPacket-Switched Networks

• The Internet uses The Internet uses Packet switchingPacket switching– Files and messages are broken down into

packets, which are electronically labeled with their origin and destination

– The destination computer collects the packets and reassembles the data from the pieces in each packet

– Each computer the packet encounters decides the best route towards its destination

7.15

Packet-Switched Network and Message Packets

7.16

The TCP/IP Internet ProtocolThe TCP/IP Internet Protocol

• Set of protocols developed by Vincent Set of protocols developed by Vincent Cerf and Robert KahnCerf and Robert Kahn– Transmission Control Protocol (TCP)

• Controls the assembly of a message into smaller Controls the assembly of a message into smaller packets before transmission, and reassembles them packets before transmission, and reassembles them once receivedonce received

– Internet Protocol (IP)• Assigns sending and destination IP Assigns sending and destination IP address to each packetaddress to each packet• Rules for routing packets from their source to their Rules for routing packets from their source to their

destinationdestination

7.17

Routers – are packet switches. • A router is connected between networks to route packets between them. • Have updateable maps of the networks on the internet• Determines the path for the packets

7.18

Open ArchitectureOpen Architecture(Internet is based on this design Philosophy)(Internet is based on this design Philosophy)

• Independent networks should not require Independent networks should not require any internal changes in order to be any internal changes in order to be connected to the networkconnected to the network

• Packets that do not arrive at their Packets that do not arrive at their destination must be retransmitteddestination must be retransmitted

• Router computers do not retain Router computers do not retain information about the packetsinformation about the packets

• No global control exists over the networkNo global control exists over the network

7.19

WAN – (Wide Area Network) Telecommunications network covering a large geographic area

LAN – (Local Area Network) Connect computers (and devices) within a limited physical area (office, building, etc.)