Dr. Tom Hickscarme.cs.trinity.edu/thicks/3342/Lectures/DCN-01... · 10. The Message Destination is the Recipient. 11. Broadcast Networks tend to be Small. 12. Multicast-Narrowcast:

11

Dr. Tom HicksComputer Science Department

Trinity University

2

3

18th Century Dominated By ?

Industrial Revolution

4


Steam Engine

5


Information Gathering

Processing

Distribution

6

Computer Systems Evolution:

First Two Decades

First Two Decades

Highly Centralized

Single Room

Glass Walls – visitors only view

Medium Sized Company/University –

only 1 or 2

Tremendously Expensive

7

Historical Tidbit #1

SAGE -- Semi-Automatic Ground Environment

– Linked Hundreds Of Radar Stations In The

United States & Canada In The First large-Scale

Computer Communications Network.

Created in 1958 – Used Till Late 60’s

Filled A Four Story Building

1,500 Instructions Per Second

32 KB RAM

600 KB of Magnetic Disk Storage

I7 177,730,000,000 I/S

8

Historical Tidbit #2

Paul Green – “Communications: Milestones & Prophecies” 1984

Quotes Bob Medcalfe ?

1960’s – 1 Mainframe Per Corporation

1970’s – 1 Microcomputer Per Branch Office

1980’s – 1 Microcomputer Office or Home

1990’s – 1 Nanocomputer In Each Appliance

Not Too

Far Off!

Inventor Of Ethernet

9

Co-Invented Ethernet

Robert Medcalfe - xerox PARC - Inteface

Message Processing

David Boggs - xerox PARC - Radio

Broadcasting

10

Computer Systems Evolution Today

Today

Powerful Computers Size Of Postage Stamp

Many Available

Inexpensive

Much More Powerful

Evaluation & Effectiveness

Criteria

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Network Evaluation Criteria

(Big Three)

Performance Reliability Security

A local area network (LAN) is defined by the Geometric Size

of the Network.

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Network Effectiveness Criteria

(Big Three)

Delivery Accuracy Timeliness

Components

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15

Five Components Of Data Communication System

1. Message – Data To Be Communicated

Message

2. Sender – Device Sending Message Computer, Camera, Telephone Handset, Television, Fax, etc.

3. Receiver – Device Receiving Message Computer, Telephone Handset, Television, Fax, etc.

4. Medium – Physical Path Fiber Optic, Twisted Pair, Coaxial, Laser, Radio Waves, etc.

5. Protocols – Communication Rules

Protocol Protocol

Data

Representation

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17

Data Representations

1. ASCII – American Standard Code For

Information Interchange – 128 symbols – 7 bits

– American National Standards Institute

2. Extended ASCII – 8 bits – left bit is always

0 8 bit bus!

3. Unicode – 16 bits – extended character set

support for languages such as Chinese

4. ISO – 32 bits – International Standards

Organization - 4,294,967,297 – support for any

symbol in the world

5. Numbers, Images, Audio, Video

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Transmission Modes

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Transmission Mode

Transmission Mode – The Transmission

Flow Direction Of Communication

Transmission Mode

Simplex Full DuplexHalf Duplex

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Simplex Transmission Mode

Simplex – Transmission Unidirectional – One Way

– A Station Can Transmit Or A Station Can

Receive – but not both

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Half-Duplex Transmission Mode

Half-Duplex – Transmission Unidirectional –Either

Station Can Transmit & Receive, but not at the

same time.

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Full-Duplex Transmission Mode

Full-Duplex –Both Stations Can Transmit &

Receive Simultaneously.

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Internetworks

Internetwork/internet – a collection

of interconnected networks.

Internet – the world wide web.

Transmission Line Configurations

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Transmission Line Configurations

Line Configuration The Way Two

Devices Attach To A Link

Transmission Line

Configuration

Point-To-Point Multiple Access

BroadcastMultipoint

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Point-To-Point Network– 1

Point-To-Point – A Line Connection With A Dedicated Link Between Two Devices

Workstation Workstation

Workstation

Mainframe

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Point-To-Point Network– 2

Most Point-To-Point Links Are

Comprised Of Physical Wire Or Fiber

Optic, but not all!


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Point-To-Point Network - 3

1. Many Connections between individual

pairs of computers.

2. A Packet often Visits Several

Intermediate Machines as it travels from

its source to its destination.

3. There are often Multiple

Possible Paths from source to

destination.

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Point-To-Point Network - 4

4. Some Paths may be Shorter/More Efficient

than others; Routing Algorithms Play an Important

Role.

5. Generally used for

Larger Networks.

6. The Internet is a

Point-To-Point network.

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Point-To-Point (P2P) Network - 5

P2P and Server-based networks differ in how each

node (host or computing device) relates to each

other.

One fundamental difference is that in a P2P:

A) each node can serve as either a client or server.

B) all nodes can serve as a client in that they make

requests.

C) all nodes can serve as a server in that they respond to

requests.

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Types Of Connections

Multipoint/ Multidrop Connection

BroadcastNetworks

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Broadcast Network

Broadcast : a Transmission Sent to Many

Unspecified Receivers at a time by means of a

computer network, radio waves, or satellite.

On an Ethernet, a broadcast packet is one which is

transmitted to all hosts on the network.

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Hub - 1

Hub : a Central Device that connects

several computers together or several

networks together.

4, 5, 8, 9, 16,

32, 64 Ports

A Passive Hub may simply forward messages

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Hub - 2

An Active Hub, or Repeater, Amplifies/

Refreshes the stream of data, which

otherwise would deteriorate over a long

distance.

4 Port Netgear Hub - Ethernet

Still Available Still In Use!

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4 Port Netgear Hub - Ethernet

Uplink To Another

Hub/Switch/Router

Network Transmission Technology: About

Broadcast Networks - 1

1. Single Communication Channel shared by all

machines

2. Messages are Broken Up into small

transmission units called Packets.

3. Each Packet contains an Address Field that

Identifies the Recipient of the Message

4. A Message [collection of packets] can be sent

by Any one Machine

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5. A Message [collection of packets] is

Received by All Machines

6. Generally One Connection between

Individual Pairs of Computers.

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192.168.000.002 192.168.000.003 192.168.000.004 192.168.000.005



7. If Message not addressed to me, ignore it!

Computer 192.168.000.003 Sends Message Addressed To Computer 192.168.000.005

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192.168.000.002 192.168.000.003 192.168.000.004 192.168.000.005

Network Transmission Technology:About Broadcast Networks - 4

7. If Message not addressed to me, ignore it!


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192.168.000.002 192.168.000.003 192.168.000.004 192.168.000.005



8. If Message is addressed to me, process it!


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192.168.000.002 192.168.000.003 192.168.000.004 192.168.000.005




Source Destination

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Network Transmission Technology:About Broadcast Networks - 7

9. The Message Source is the Sender.

10. The Message Destination is the Recipient.

11. Broadcast Networks tend to be Small.

12. Multicast-Narrowcast: a broadcast

Transmission that is Transmitted to only a Subset

of the Network.

13. Broadcasting differs from Multicasting and Narrowcasting, in which a Transmission is sent to a group of selected receivers.

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Human Broadcasting?

Do Humans ever process broadcasting

messages like a passive hub?

Watson, come here, I want you!

Do Humans ever process broadcasting messages like a active hub?

Watson, come here, I want you! [into a public address system or bull horn]

Protocols

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Protocols – 1

Ethernet: IEEE 802.3 Protocol

Speeds: Ethernet 10 - 100 Mbps

IBM Token Ring: IEEE 802.5 Protocol Speeds: Token Ring 4 – 16 Mbps

DBDQ: IEEE 802.6 Protocol– Two one-way buses

Protocol – a Set of Rules or Standard designed so that Computers can Exchange Information with a Minimum of Errors. [High-Tech

Dictionary]

P

R

O

T

O

C

O

L

S

Only A SampleOf Protocols

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Protocols - 2

3 Key Elements Of Protocol

1. Syntax- Structure & Format Of The Binary

Data – How Bits Are Organized

2. Semantics – Meaning of Each Collection Of

Bits

3. Timing – When and How Fast Data Can Be

Sent

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Protocols - 3

De Jure Standards – “by law” - Standards

Legislated By Officially Recognized Body

De Facto Standards – “by fact” - Standards

Not Legislated By Officially Recognized Body But

Already Adopted For Widespread Use

Network BuildingBlocks

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Network Building Blocks

Nodes

A Node is a Processing Location an

autonomous Computer or some other Device,

such as a Printer, Router, Gateway, Switch,

etc.

Every Node has a Unique Network Address,

sometimes called a Data Link Control (DLC)

address or Media Access Control (MAC)

address. Links

A Link is the physical connection

coax cable, twisted pair, optical

fiber, microwave, radio wave, etc.

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Computer Network

“A Computer Network is a set of devices

connected by media links” [Forouzan]


Workstation


Workstation

“A Computer Network is an interconnected

collection of autonomous computers” [Tanenbaum]

A Computer Network is two or more

connected nodes.

Interconnected Computers?

“Two Computers are Connected if they can

Exchange Information” [Tanenbaum]

3 Major Wired Connection Types Include

• Twisted Pair

• Coaxial

• Fiber Optic

3 Major Wireless Connection Types Include

• Radio Transmission

• Microwave Transmission

• Light wave Transmission54

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Autonomous Computer?

An Autonomous Computer is a computer that is

not involved in a Master/Slave relationship [one

that enables one computer to stop, start, or control

another].

Mainframe – Terminals IS MASTER-SLAVE

Relationship

Therefore Not autonomous

Categories Of

Networks

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Categories Of Network Scale

DAN LAN MAN WAN

1. DAN – Desk Area Network {DeskTop}

2. LAN – Local Area Network {Room, Building,

Campus}

3. MAN – Metropolitan Area Network {City}

4. WAN – Wide Area Network {Country, Continent}

DAN

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DAN - 1

DAN – Desk Area Network

Privately owned

Configuration - DistanceDesk/Close [1-4 Meters]

Share Printers, Files, Programs

Internet Connections, Data,

Calendars, etc.

Speeds generally 10 Mbps or 100 MbpsMbps – megabits/sec – 1,000,000 bits per second (not 1,048,576

bits per second)

MB/sec – megabytes/sec

Low Delay

Very Few Errors


DAN - 2

DAN – Topology Options

Generally Star

LAN

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LAN - 1

LAN – Local Area Network

Privately owned

Generally Single Cable Configuration - Distance

Room [Meters]

Building [100 Meters]

Campus [Kilometers]

Share Printers, Files, Programs

Internet Connections, Data,

Calendars, etc.

May include multiple hubs

Low Delay

Very Few Errors

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LAN

Ethernet IEEE 802.3 Protocol

Broadcast Transmission

Any one computer may become master and

transmit

All other machines must refrain from sending


LAN - 2

My Turn To

SendNo Its My Turn

To Send

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LAN - 3

Ethernet IEEE 802.3 Protocol

Protocol - a Set of Rules or standard

designed so that Computers Can Exchange

Information with a minimum of errors.

IEEE : Institute of Electrical and Electronics

Engineers -www.ieee.org – A membership

organization that includes engineers, scientists

and students in electronics and allied fields.

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LAN - 4

LAN – Topology Options

1. Star Topology

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LAN - 5

Hub/Switch Symbol For Slides

=

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LAN - 6

LAN – Topology Options

2. Bus/Linear Topology

Ethernet IEEE 802.3 Protocol Speeds: Ethernet 10 - 100 Mbps

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LAN - 7

LAN Topology Options (cont)

3. Ring Topology

IBM Token Ring IEEE 802.5 Protocol Speeds: Token Ring 4 – 16 Mbps

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LAN - 8

LAN Topology Options (cont)

4. Complete/Mesh/Fully Connected

Topology

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LAN

Broadcast Static or Dynamic Static: Partition time to each system and cycle

Wastes time and slots when system has nothing to say

Dynamic: Send on demand – when ready

Arbitration mechanism resolves conflicts when two attempt to transmit at the same time

• Strategy Example: Both wait a random amount of time and try again

Centralized or Decentralized

• Centralized: A single unit, such as a bus arbitration unit, which decides who is to go next

• Decentralized: Each machine must decide for itself whether or not to broadcast


LAN - 9

Processing

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Centralized Processing

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Centralized Processing is processing Performed in One

Computer or in a cluster of coupled computers in a single

location.

Access to the computer is via "Dumb Terminals," which send

only input and receive output or "Smart Terminals," which add

screen formatting. All data processing is performed in the central

computer.

The first Computers in the 1950s, which were stand-alone with

all Input and Output Devices in the Same Room. Starting in the

1960s, terminals were added throughout a company's

headquarters and branch offices, and each terminal was wired

into the central machine (i.e. networking).

Terminals Became PCs

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As Personal Computers and Local Area Networks (LANs)

proliferated in the 1980s &1990s, Terminals were Replaced

with PCs, which were made to function like a terminal with

the addition of hardware and software. Users could Run

their Own Applications and still Access the Central

Computer as required.

By the 1990s, "Client/Server" Architecture began to

Replace Terminal Access. Client PCs communicated with

network servers via the local network rather than terminals

hardwired to a central machine. Although there are still

hardwired terminals in use, the Predominant Technology

Today is the Local Area Network (LAN).

Thin Clients

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The Terminal-Based Centralized Architecture is hardly

defunct.

Harking back to the early days, options within Windows and

Unix/Linux servers, as well as software from companies such

as VMware and Citrix, Enable Applications to be Run in

Network Servers with the user's computer turned once again

into a terminal.

This is now known as "Thin Client" computing rather than

centralized processing, it is, however, a very similar concept.

MAN

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MAN - 1

MAN – Metropolitan Area Network

Configuration - Distance

City [ ~ 10 Kilometers]

One or Two Cables

No Switching Elements

Topology

DQDB – Distributed Queue Dual Bus for 2 cable configuration [often used]

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MAN –2 - Topology Options

1. DBDQ: IEEE 802.6 – Two one-way buses Packets travel from the Head and fall off

Travel Bus A if Computer to Right

Travel Bus B if Computer to Left

Optimize delivery

WAN

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WAN – Wide Area Network

Also called an End System

Configuration - Distance

Country [ ~ 100 Kilometers]

Continent [ ~ 1,100 Kilometers]

Workstations called

Hosts


WAN - 1

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WAN – Wide Area Network

Hosts are connected by a Communication

Subnet or Subnet

Two components of WAN are Transmission

Lines & Routers

Transmission Lines move bits between

machines; they are also called Circuits,

Channels, and/or Trunks

Switching Elements are specialized computers

connecting two or more transmission lines; they

are often called Routers. Routers forward

packets of information thorough our networks.


WAN - 1

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Router - 1

Router – A device that Forwards Data Packets from one

LAN/WAN to another.

The Router uses Routing Tables and Routing Protocols.

Routers Read the Network Address in each transmitted

frame & make a Decision on how/where to send it based

on the most expedient route (traffic load, line costs, speed,

bad lines, etc.).

[TechWeb Encyclopedia]

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Router - 2[Computer Desktop Encyclopedia]

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Router - 3

Router (cont)

Routers are used to segment LANs in order to

Balance Traffic within workgroups

Routers are used to Filter Traffic for security

purposes and policy management.

Routers work at layer 3 in the protocol stack.

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WAN - 2

WAN – Assembling the components

LAN

LAN With Router

Host/Workstation

Host/Laptop

Host/Server

Router/Switching Element

Transmission Line, Circuit, Trunk, Channel

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WAN - 3

WAN – Assembling the components (cont)

Subnet

Subnet (original meaning) – “a collection of routers and communication lines that move packets from the source to the destination”. [Tanenbaum] Dual Meaning – Nothing

replaced original

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WAN - 4

WAN – Assembling the components (cont) Subnet

Subnet

If two routers do not share a cable with the router with whom they wish to communicate, they must do so indirectly using other routers.

Source

Destination

More Than One Route From Source To Destination?

Network

Topologies

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WAN - 5

WAN – Topology Options

Components

1. Bus/Linear Topology

Transmission Line LANL

L L LL L

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WAN - 6

WAN Topology Options (cont)

2. Ring Topology

L

LL

L

L

LL

90


WAN - 7


3. Star Topology

L

LL

L

L

LL

L

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WAN - 8


4. Tree Topology

L L

L

L L

L

LL

L L LL L L L

L

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WAN - 9


4. Tree Topology

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WAN - 10


5. Complete/Mesh/Fully ConnectedTopology

L

LL

L

L

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WAN - 11


6. Irregular Topology

L

LL

L

L

L

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WAN – 12


7. Hybrid Topology

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WAN – Satellite or Ground Radio Solutions - 13

Each Router has an antenna through which it

can send and receive

All satellite routers can hear output from the

satellite

Some satellite routers can hear upward transmissions from fellow satellite routers

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WAN – Satellite or Ground Radio Solutions - 14

Lots of Potential Combinations!

Subnet

NetworkHardware Devices

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Network Hardware Devices

1. Hub

2. Router

3. Gateway

4. Switch

5. Bridge

6. Repeater

Hub

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Hub - 1

Hub : a central device that connects several

computers together or several networks

together.

A Passive Hub may simply forward messages

102

Hub - 2

An Active Hub, or Repeater, Amplifies/

Refreshes the stream of data, which

otherwise would deteriorate over a long

distance.

Router

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Router - 1

Router – A device that Forwards Data Packets from one

LAN/WAN to another.

The Router uses Routing Tables and Routing Protocols.

Routers Read the Network Address in each transmitted

frame & make a Decision on how/where to send it based

on the most expedient route (traffic load, line costs, speed,

bad lines, etc.).

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Router - 2

Routers are used to segment LANs in order to

Balance Traffic within workgroups

Routers are used to Filter Traffic for security

purposes and policy management.

Routers work at layer 3 in the protocol stack.

Gateway

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Gateway - 1

A Gateway is a Computer that Performs Protocol

Conversion between Different Types of Networks.

For example, a gateway can convert a TCP/IP packet to a

NetWare IPX packet and vice versa, or from AppleTalk to

DECnet, from SNA to AppleTalk and so on.


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Gateway - 2

A Gateway is also a Computer that Acts as a Go-Between Two or More Networks that use the Same Protocols.

In this case, the gateway functions as an entry/exit point to the network. Transport Protocol Conversion may not be required, but some form of Processing is typically performed. (Maybe proxy server?). [TechWeb Encyclopedia]

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Gateway - 3

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Gateway - 4

Switch

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LAN Switch - 1

A Switch is a network device that cross connects

stations or LAN segments. Also known as a "frame

switch," LAN switches are available for Ethernet,

Fast Ethernet, Token Ring and FDDI.

Each sender/receiver pair has the full Switch (Maybe

100 Mbps) capacity. Each port on the switch can give

full bandwidth to a single server or client station or it

can be connected to a hub with several stations.

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LAN Switch - 2


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LAN Switch & Hub


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LAN Switches

Switches

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Bridge

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Bridge - 1

Bridge - A device that connects two LAN segments together, which may be of similar or dissimilar types, such as Ethernet and Token Ring. A bridge is inserted into a network to segment it and keep traffic contained within the segments to improve performance.

Bridges learn from experience and build and maintain address tables of the nodes on the network. By monitoring which station acknowledged receipt of the address, they learn which nodes belong to the segment.


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Bridge - 2

Bridges work at the data link layer (OSI layer

2), whereas routers work at the network layer

(layer 3).

Bridges are Protocol Independent; Routers

are Protocol Dependent.

Bridges are faster than routers because they do

not have to read the protocol to glean routing

information.


Repeater

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Repeater

Repeater - (1) A communications device that amplifies or regenerates the data signal in order to extend the transmission distance.Available for both analog and digital signals, it is used extensively in long distance transmission. It is also used to tie two LANs of the same type together. Repeaters work at layer 1 of the OSI model.

(2) The term may also refer to a multiport repeater, which is a hub in a 10BaseT network.


WirelessNetworks

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Wireless Networks - 1

PDA – Personal Digital Assistants connect to

Internet

Technology is similar to Ship To Shore technology invented by Italian Physicist Guglielmo Marconi in 1901

Wireless Portable Office [land, sea, or air]

E-Mail

Receive/Send Fax

Access remote Data

Log in on remote systems

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Easy To Install

Slower Transmission Speed [Most Are 11-56 Mpbs]

Higher Error Rates

Transmissions can interfere with one another

Some Universities have wireless access

Columbia

Mostly for Library Access

Airplane

Many wireless transmission hosts

Alternative - LAN with wireless connection

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Bob Metcalfe – Inventor of Ethernet

“Mobile wireless computers are like mobile pipeless

bathrooms – portapotties. They will be common on

vehicles and construction sites and rock concerts.

My advice is to wire up your home and stay there.”

What do you think?

Distributed System

vs

Computer Network

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Distributed System vs. Computer Network

O

V

E

R

L

A

P

Computer Network Process

User logs into specific computer

Each autonomous computer is clearly identified

Run a program – User must explicitly find/move files and direct a specific computer to initiate execution of the program.

128

Distributed System vs. Computer Network

Distributed System Process

User logs into network

Existence of multiple autonomous

computers is transparent; it is the division of

one task among multiple computers.

Run a program – the operating system finds

all essential files, transports all essential

files, select the best processor, initiates

execution of the program.

O

V

E

R

L

A

P

Reasons Companies

Network

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130

5 Reasons

Why Companies Most Often Network

I. Share Resources Programs

Data

Equipment

II. High Reliability Of Data SharingData accessible on two or more systems

Program that can be run on two or more systems

III. Save MoneyBetter Price/Performance Ratio

Mainframe – ten times faster? – costs thousands of times more

IV. ScalabilityIncrease performance by adding more processors [much cheaper than

mainframe expansion]

V. Powerful Communication Medium Among EmployeesIntranet – mail – info – joint projects – file share – etc.

Client-Server Relationship

Two devices communicating on a network are

engaged in a "request/response" process.

We formally know this type of data

communication relationship to be the Client-

Server Relationship.

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Company Networking:

Client-Server Model

Usually many more clients than servers.

client-workstation

server

client-workstation

client-workstation1. Request message sent from client to server

requesting work/processing/data/etc.

Request

2. Server does the requested work and sends back the appropriate reply.

Reply

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About Data Communications

A Data Communication System must

Transmit Data to the Correct

Destination in an Accurate and Timely

Manner.

Networks use Distributed Processing

in which a Task is divided among multiple

computers.

Reasons PeopleNetwork

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135

3 Reasons

Why People Network

I. Access Remote Information

Banking

Investments/Stocks

Newspapers & Magazines

WWW Info/Education

II. Person To Person CommunicationE-Mail

Chat Rooms – talk/ytalk

Videoconference

III. EntertainmentMovies & Music

Multi-Player Video Games

Interactive Television

Television/Movies on Demand (Coming)

SocialIssues

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Computer Networking:

New Social Issues

People can share views

Newsgroups

Bulletin Boards

Chat Rooms

Posted views may be offensive to others!

Where Is The Accountability? Should There Be?

138

Social Issues –

Historical Communication

Legal accountability for that which you publish?

Legal accountability for that which you say?

What about this new medium? – How should it be policed? Should it be policed?

139

Social Issues:

What Do You Think About

Off-Color Language? – What limits on

profanity?

Ethnic Bashing?

White Supremacy – Religious Bashing

Pornography?

Who differentiates between pornography and art?

Child Pornography?

Posting Private Information?

Video Cams from your dorm room/bath room?

140

Social Issues:

Ownership

Company E-Mail

Company bears all hardware, software, connection, and employee time expenses

Right To Sensor/Examine?

University E-Mail University bears all hardware, software, connection?

Right To Sensor/Examine?

Anonymous Messages Whistle blower

Right to face your accusers?

Whole New Collection Of Social Issues –Graduate Course!

Performance, Reliability, & Social

Criteria

141

142

Performance Criteria

Network Evaluation Criteria I

Performance is usually measured in time –

Transmit Time + Response Time

4 Major Factors Influencing Performance 1. Number of Users – Network

Accommodate Traffic

2. Type Of Transmission Media – 100 Mbps vs. 10 Mbps vs. ??

3. Hardware – High Speed Computer –Memory/Drives/etc.

4. Software - Windows 2000 throughput is ~30% greater than NT throughput.

143

Reliability Criteria

Network Evaluation Criteria II

Reliability is usually measured by frequency of failures or the time it takes to recover from a failure.

3 Factors Influencing Reliability 1. Frequency of Failure – “All Networks

Fail Occasionally” [Forouzan]

2. Recovery Time After Network Failure– How long to restore service

3. Castrophe – How well network is protected against fire, earthquake,tidal wave, etc.

144

Security Criteria

Network Evaluation Criteria III

Security is protection against virus and

unauthorized access

2 Factors Influencing Securityo 1. Virus –

• Virus Software Programs

• Software Firewalls

• Hardware Firewalls

• Port Blocking

o 2. Unauthorized Access -

• User Passwords, Usernames, and Individual Permissions & Group Permissions

• Data Encryption

145

Network Protection

Protection of Data from a Natural

Disaster such as a tornado is a

Network Management Issue.

Organizations YouShould Know

146

147

ISO - International Organization for

Standardization

ISO (International Standards Organization)

Charge – provide standardization

for compatibility in a variety of fields.

Created 1947

82+ Industrial Nations

Volunteer Organization

ANSI – American National Standards

Institute is US Representative in ISO

Created Open Systems Interconnection

(OSI) Model For Network Communications

148

ANSI – American National Standards Institute

ANSI – American National Standards Institute

Charge – Lead A Standardization Charge

Which Will Advance US Economy And Serve

US Citizens

Membership includes professional societies,

industry associations, governmental bodies,

regulatory bodies, & consumer groups

Private Non-Profit Organization

Not Affiliated With US Government

US Voting Member In ISO –

International Standards Organization

149

ITU-T – International Telecommunications Union -

Teleommunications

ITU-T - International Telecommunications Union

– Telecommunications Standard Sector

Charge – UN Committee to standardize

International Telegraphy and Telephony

Started in 1970’s – Name change in 1993

Study Groups – each with separate charge

ANSI and CEPT (Committee of European

Post, Telegraph, & Telephone) Submit

Proposals To ITU-U [Ex. V Series: V.32, V.33, V.42

Series: X.25, X.400, X.500]]

ISDN – Integrated Services Digital

Network - Standards

150

IEEE : Institute of Electrical and Electronics Engineers

IEEE : Institute of Electrical and Electronics

Engineers

Charge – advance theory, creativity , and

product quality in engineering to create

standards for computing and communications.

Created in 1963 - 300,000+ members

Project 802 – LAN subcommittee

Membership organization includes

engineers, scientists and students in electronics

and allied fields

www.ieee.org

151

EIA – Electronic Industries Association

EIA – Electronic Industries Association

Devoted to Manufacturing Concerns

Non-Profit

Standards Development

Public Education & Lobbying

Helped To Define Serial Transmissions Between

Two Digital Devices –

(Computer to Modem) EIA-232

152

Bell Laboratories Alcatel-Lucent

Formerly Called AT & T Bell Labs

R&D (Research & Development) for

Advanced Communications

Murray Hill, New Jersey

Major Forums

153

154

Forums - 1

Technology is moving faster than the

standards groups can can ratify

standards.

Forums, made up of individuals from interested organizations, have been established to help create working models.

Work With Universities & Users To Quickly Test, Evaluate, & Standardize New Technologies

155

Forums - 2

Major Forums

Frame Relay ForumDEC, CISCO, Northern Telcom, Strata Com

Flow Control & Multicasting

ATM Forum and ATM ConsortiumPromote Acceptance of Asynchronous Transfer Mode Technology

Internet Society (ISOC) and Internet

Engineering Task Force (IETF)Speed, Growth, & Evolution Of Internet Communications

Contribution SNTP – Simple Network Management

Protocol

156

FCC – Federal Communications Commission

FCC – Federal Communications Commission –

Regulates all communication technology in the

United States.

Protect The Public – Regulate Wireless, Radio,

Television, Cable, etc.

Each Country Has Such An Agency!

Internet

157

158

Internet - Lots Of Users-

Lots Of Networks

http://www.internetliv

estats.com/internet-

users/

http://www.internetlivestats.com/internet-users/

159

IMP, DOD, ARPA

ARPANET & History - 1

DoD – Department of Defense

Telephone Net Too Easy To Knock Out –Nuclear War

ARPA – Advanced Research Projects AgencyNo Labs

Issued Contract

Packet-Switched Network With Subnet & Host Of Computers

IMP – Interface Message Processors –Used as Subnet MinicomputersEach IMP connected to at least 2 other IMPs

Datagram Subnet - Alternate Routes – Messages Automatically Re-Routed

160

Store-And-Forward, BBN


Each Node – IMP & Host Connected By Short

Wire In Same Room

Host Could Send Message (<= 8,063 Bytes) To IMP

IMP Break Message Into Packets (1,008 Bytes)

Store-And-Forward – Each Packet ReceivedIn It’s Entirety Before Passed On

First Store-And-Forward Packet-Switching Network

BBN Selected To Build Network [of 12 Companies]

December 1968

161

Original ARPANET Design


BBN Used Modified Diskless Honneywell DDP-316’s as

Interface Message Processors.

IMP’s Connected Leased Lines – Message Passed, BBN

Finished.

162

Growth


163

TCP/IP, Satellites, Mobile Radio

ARPANET & History – 5

ARPA Funded Satellite Networks

ARPA Funded Mobile Packet RadioNetworks

ARPANET Protocols Not Suitable For Multiple Networks

Protocol Research – Cerf & Kahn Developed TCP/IPin 1974

ARPA Contracts With Berkley & BBN

Berkley UNIX With TCP/IP

Convenient Program To Interface Network Sockets

Wrote Many Network Management Utilities & Apps

164

Success, MILINET, DNS, Death

ARPANET & History – 6

1983 – Stable – 200 IMPs & Hundreds of Hosts

1983 - ARPA Turned Management Of Network Over To DCA - Defense Communications Agency

DCA - Partition Off MILINET

1980’s Network Getting Larger & Expensive

Finding Hosts Expensive – DNS Developed –Domain Naming System

1990 ARPANET Dead – MILINET Lives!

165

CSNET & History – 1

ARPANET Avail Only To Universities With

Government Contracts

1970’s NSF – National Science Foundation –saw benefit of collaborative research and information distribution.

Backdoored through single machine at BBN [dial

up] for years

1984 – NSF Started Design of NSFNET

Backbone – 6 Supercomputers

San Diego, Boulder, Champaign, Pittsburgh, Ithica, & Princeton

166

Supercomputer & Fuzzball


Each Supercomputer

Little Brother – Microcomputer – “Fuzzball”

Fuzzballs Connected With Leased Lines

167


NFS Funded 20 Regional Networks

Success From The Beginning!

Fiber Optic To Increase Speed – Overwhelmed Again!

MERIT – Michigan Based Consortium – Awarded Contract To Run CSNET

1980’s Network Getting Larger & Expensive

ANS - Advanced Networks & Services –non-profit organization [IBM, MERIT, MCI] given charge to prepare for commercialization in 1990.

Overview

168

169

Overview

170

Chapter 1 Acronyms

DLC

MSC

ANSI

OSI

ISO

ITU-T

CEPT

ISDN

IEEE

EIA

ISOL

IETF

FCC

DAN

LAN

MAN

WAN

DQDB

PDA

171

Data Communications & Networking

CSCI 3342

Dr. Thomas E. HicksComputer Science Department

Trinity University

Textbook: Computer Networks

By Andrew Tanenbaum

Textbook: Data Communications & Networking

By Behrouz Forouzan

Special Thanks To WCB/McGraw-Hill For Providing

Graphics For

Many Text Book Figures For Use In This Presentation.

Documents

Dr. Tom Hickscarme.cs.trinity.edu/thicks/3342/Lectures/DCN-01... · 10. The Message Destination is the Recipient. 11. Broadcast Networks tend to be Small. 12. Multicast-Narrowcast: