jozef goetz, 2009 1 1 standards clear visible standards. students must have clear understandings...

Jozef Goetz, 2009

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Standards

Clear visible standards. Students must have clear understandings

learning standards in the areas of learning goals, lecture notes assignments and getting basic academics and applications skills.

I would like to establish a clear system of standards

learning standards are aligned with your expectations and the expectations of the global marketplace

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Standards Communication delivered over multiple

channels is more efficient than communication over a single channel.

Multiple channels make it more likely that the whole message will be received.

An appropriate picture adds another

channel by making a visual connection to an abstract

idea. PowerPoint makes it easy to create

visuals, and by using a template, makes it easy to be consistent.

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Research-based principles for designPower Point presentation

Educational psychologist, Richard Mayer, posits a theory of multimedia learning wherein he finds seven research-based principles for design.

• Students learn better 1. from words and pictures than from words alone

(Multimedia Principle)2. when corresponding words and pictures are

presented near rather than far from each other on the page or screen (Special Contiguity Principle)

3. when corresponding words and pictures are presented simultaneously rather than successively (Temporal Contiguity Principle)

Mayer, R. (2001). Multimedia Learning. Cambridge University Press. Rodriguez, R. (2005) Theories Into Practice with Blackboard ONLINE,

University of La Verne.

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Eyes are attracted to great contrast●Contrast should fit information relevance●Important information should have high

contrast I use color or/and color

●Less relevant details should have lower contrast

Context should be hierarchical●Group related contexts● More details should be indented

Lecture Notes presentation

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Our eyes are attracted to:

●Size●Contrast●Texture●Depth●Motion

To control focus, we use:●Larger size●Greater contrast●Different color●Hierarchy

●Should be easy to ignore lower levels as familiarity increases

●Sometimes animation


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Addition to that we introduce1. Hierarchy of bullets

Nested bulleted and numbered lists Level 1 item 1

Level 2 item 1 Level 2 item 2

Level 1 item 2 1. Level 2 item 1 2. Level 2 item 2

Higher level more general info Lower level more specific info

2. Key words in red3. Important words in bold4. Ability to learn from slides

Example: Distributed Computing

Work distributed over networks N-Tier applications

Split parts of applications over numerous computers1. User interface2. Business-logic processing3. Database

Different parts interact when application runs

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My Lecture Notes:Have tutorial values: Comply with research-based principles

for design Power Point presentation Concepts are presented visually with

many diagrams and pictures. They use visual aids (diagrams, pictures

etc.) and pictures are presented near each other on the page or screen.

The context is presented in the hierarchical way, details are indented

Important key words are highlighted or written in different color

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Overview of Overview of Data Communications Data Communications

and and NetworkingNetworking

PART IPART I

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

expanded by Jozef Goetz, 2009

Jozef Goetz, 2009

9Overview

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Chapters

Chapter 1 Introduction

Chapter 2 Network Models

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Chapter 1

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1.1 Data Communication

•The term The term teletelecommunicationcommunication means communication means communication at a at a distance.distance.

•The word The word datadata refers to refers to information presented in information presented in whatever formwhatever form is agreed upon by the parties creating and is agreed upon by the parties creating and using the data. using the data.

•Data communicationsData communications are the are the exchange of exchange of datadata between two devicesbetween two devices viavia some form of some form of transmission transmission mediummedium such as a wire cable. such as a wire cable.

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1.1 Data Communication•Data communication is the transfer of data from one device to another via some form of transmission medium.

•A data communications system must transmit data to the correct destination in an accurate and timely manner.

A. ComponentsB. Data RepresentationC. Direction of Data Flow

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14A. Five components of data communication

are the message, sender, receiver, medium, and protocol.

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B. Data Representation

text, numbers, images, audio, and video are different forms of information.

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Figure 1.2 Simplexe.g. the keyboard and the monitor

C. Direction of Data Flow

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Figure 1.2 Half-duplexe.g. Walkie-talkies, CB radios

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20Figure 1.2 Full-duplex

e.g. 2 people are communicating by a tel. line

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A network is a set of communication devices connected by media links. • A A networknetwork is a is a set of devicesset of devices (often (often

referred to as referred to as nodesnodes) connected by ) connected by communication communication linkslinks. .

• A A nodenode can be a can be a computer, printercomputer, printer, , routerrouter or or any other deviceany other device capable of capable of sendingsending and/or and/or receiving datareceiving data generated by other nodes on the network.generated by other nodes on the network.

1.2 Networks

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1. Distributed Processing• Task is divided

2. Network Criteria should be met• Important:

1. Performance• Metrics – they are contradictory

• Transit time (from A to B)• Response time• Throughput -How much data is sent• Delay -traffic congestion

2. Reliability• Measured by the freq. of failure

3. Security• Protecting data from unauthorized

access and damage3. Physical Structures4. Categories of Networks

1.2 Networks

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Figure 1.3 Point-to-point connection

Physical Structures

ad 3. Physical Structures

In a point-to-point connection, two and only two devices are connected by a dedicated link.

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Figure 1.3 Multipoint connection (timeshare connection – capacity)

In a multipoint connection, three or more devices share a link.

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1.2 NETWORKS

How do we categorize? Topology, geography Technology

Topologies Wide area networks - WAN Metropolitan networks - MAN Local area networks - LAN Personal networks - PN

Technologies Circuit switched Packet switched

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Figure 1.4 Categories of topology (a network is layout physically)

A topology is the geometric representation of the relationship of all the links and linking devices

4. Categories of Networks

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27Figure 1.5 Fully connected mesh topology (for five devices)

Every device has a dedicated point to point link to every other device

How many physical links do we need for n nodes (devices)?

-’s: •Expensive•Huge amount of cabling

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28Figure 1.6 Star topology

Each device has a dedicated point to point link only to a central controller, called a hub

If one device wants to send data to another. •It sends the data to the controller, which then relays the data to the other connected device.

So, it doesn’t allow direct traffic between devices

-’s: If one link fails, only that link is effected.

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Figure 1.7 Bus topology is multipoint, previous all were point to point

connection

One long cable acts as a backbone

+s:•include ease of installation nodes are connected to the bus cable by drop lines and taps•cable redundancy is eliminated

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Figure 1.8 Ring topology

Each device has a dedicated point to point link only with 2 devices on either side of it.

When a device receives a signal intended for another device, its repeater regenerates the bits and passes them along.

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Figure 1.9 A hybrid topology: a star backbone with three bus networks

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Figure 1.10 An isolated LAN connecting 12 computers to a hub in a closet

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33 Categories of networks

A network falls is determined by criteria:1. Its size2. Its ownership3. The distance

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Networks LAN -- Local Area Network

Usually confined to a single building or group of buildings

MAN -- Metropolitan Area Network Connects computer resources in a local

geographical area e.g. city

WAN -- Wide Area Network Usually uses some form of public or

commercial communications network to connect computers is widely dispersed geographical areas e.g. regions, countries, states, with a minimum distance typical of that between major metropolitan areas.

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35 LAN - Local Area Network

•Designed for a single office, campus, building or between nearby buildings. •LANs allow resources to be shared

•Hardware•Software•Data

between PCs or workstations.•License restriction

• LANs are distinguished by three characteristics:– size

restricted in size based on the size of the campus or building. – transmission technology

broadcast networks– topology

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LANs - Transmission

• LANs are usually broadcast networks that are connected by a cable that attaches all of the computers together.

• LANs can run at speeds from 10Mbps to 10Gbps depending on the technology.

• LAN delays are usually small (microseconds) and few errors (scrambled data) occur.

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LAN (Continued)

A given LAN use only one type of transmission medium.

Speed : 4-16 MbpsToday: 10 Gbps

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MAN - Metropolitan Area Network (e.g. cable TV)

Designed to extend over an entire city, connects LANs

LANs can be shared

- offices can be connected via a city

Best known example – a cable TV network.Originally intended for TV only, it quickly became used for computer networks once the cable companies determined that there was money to be made.

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39 WAN - Wide Area Network

Provides all transmission (data, video, image etc.) over large areas e.g. states, countries, a continent , or the whole world.

In contrast to LANs may utilize public, leased, or private communication equipment.

• The user computers in a WAN are called hosts (owned by the customers).

• Host computers on various LANs are connected via a communication subnet (owned by a tel company or Internet service provider).

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40Wide Area Networks

Relation between hosts on LANs and the subnet. The subnet consists of routers and

transmission lines. A router is a specialized piece of switching hardware

that is responsible for determining the direction that data packets should be sent.

Routers are responsible for directing data down transmission lines from one LAN to another.

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41Figure 1.11 WANs: a. a switched WAN - use routers to coonect LANs and WANs b. a point-to-point WAN

WAN can be as complex as the backbones that connect the Internet or a home computersto the Internet

•leased line•dial up connection

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42Wide Area Networks

A stream of packets from sender to receiver. A subnet is organized according to the principle called

store-and-forward or packet-switched subnet– The message sent by a process is broken down into smaller

packets to send.– Each packet is sent out onto the network.– As a packet arrives at a router, it is stored (store-and-forward)

there until the outgoing line is free. It is then sent on it’s way.– All the packets make take the same or different routes

depending on if they are individually routed or not.

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A WAN connecting two LANs

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44Figure 1.12 e.g. A heterogeneous network made of four WANs and two LANs

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Subnets (cont’d)

• It is possible to have a broadcast subnet.

• The best example is a satellite system, where the data is broadcast to everyone.

• With a satellite, no routing occurs at the satellite – it simply acts as a big dish to bounce signals off of.

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Wireless Networks.

• Wireless networks can be divided into three main categories:

A.– System InterconnectionB.– Wireless LANsC.– Wireless WANs

• Lets take a look at these three categories…

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47A. System Interconnection

• We can use wireless technology to interconnect our system.– wireless mouse– wireless keyboard– wireless PDA

• Bluetooth is a wireless technology that would allow all sorts of digital devices (cameras, headsets, scanners, computers ) to “talk” to each other just by being close.

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Wireless Networks

(a) Bluetooth configuration (master-slave paradigm, master determines how long, when and frequency slaves can use)

(b) Wireless LANComputers and printers can connect to the network with a radio

communication link.There is usually a (or some) central access point or base station

where the radio connections are converted to wire connections.

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49B. Wireless LANs

• Computers may also be able to talk directly to one another if close enough together.

Wireless is great for old homes you don’t want to wire and laptops that you want to be able to move around with.

• The standard is IEEE 802.11.• It works on the same frequency as 2.4

GHz portable phones and Bluetooth.There are some compatibility issues between 802.11

and Bluetooth that have to be worked out.

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50C. Wireless WANs – IEEE 802.16

• Cell phone networks are a good example of wireless WANs.

• We are on our third generation of wireless WANs – there was

analog voice, digital voice, and now digital voice and data.

• Distances are much greater than LANs, but bandwidth is much lower.

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Wireless Networks

(a) Individual mobile computers(b) A flying LAN

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52Home Network Categories.

Many devices are capable of being networked: Computers (desktop PC, PDA, shared peripherals) Entertainment (TV, DVD, VCR, camera, stereo,

MP3) Telecomm (telephone, cell phone, intercom, fax) Appliances (microwave, fridge, clock, furnace,

airco, lights) Telemetry (utility meter, burglar alarm,

thermostat, babycam).

• Many of us have them already – multiple computers all connected.

• What about connections to phones, entertainment systems, appliances and other devices?

• How practical is a home network? • Will people pay so that their toaster can talk to their fridge?

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53Home Network Categories

Requirements:1.Easy to install, manage2.Foolproof in operation3.High performance to connect

multimedia devices 4.Low cost5.Expand the network gradually6.Secure and reliable

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Internetworks

Replace the subnet by a WAN we’ll get Internetworks. The subnet consists of routers and

transmission lines. A WAN contains both routers and hosts

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Internetworks

A collection of interconnected networks is called an internetwork or internet.

Connections are usually made through gateways that can provide the translation between the two different technologies.

An internetwork is formed when distinct networks are connected ex: a LAN and a WAN or two LANs are connected

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Q 1- 10 ? p.24Q 1- 10 ? p.24

TEST YOUR UNDERSTANDING

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1.3 The Internet1.3 The Internet

•The The InternetInternet has has revolutionized many aspectsrevolutionized many aspects of our of our daily lives. daily lives.

•It has It has affectedaffected the way we the way we do businessdo business as well as the as well as the way we way we spend our leisure timespend our leisure time. .

•The Internet is a The Internet is a communication systemcommunication system that has that has broughtbrought a wealth of a wealth of information to our fingertipsinformation to our fingertips and and organized it for our useorganized it for our use. .

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1.3 The Internet1.3 The Internet•A Brief History•The Internet Today

•When 2 or more networks are connected, they become an internetwork, or internet.

•An internet is a network of networks. •An "internet" (lower case i) is any computers connected to each other (a network), and are not part of the Internet unless the use TCP/IP protocols.

•The Internet (upper case) is a collaboration of more than 100s thousands interconnected networks.INTERNET (Upper case I) The vast collection of interconnected networks that all use the TCP/IP protocols and that evolved from the ARPANET of the late 60’s and early 70’s.

•The Internet is a structured, organized collection of many separate networks.

•TCP/IP is the protocol suite for the Internet.

•An "intranet" is a private network inside a company or organization that uses the same kinds of software that you would find on the public Internet, but that is only for internal use. An intranet may be on the Internet or may simply be a network.

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59What is the World Wide Web?

From the Free Online Dictionary of Computing, we get this definition from its entry for WWW:

"An Internet client-server hypertext

distributed information retrieval system." The Web is not a network. The Web is not the Internet itself. The Web is not a proprietary system like AOL. Instead the Web is a system of clients (Web browsers) and servers that uses the Internet for its data exchange.

On the WWW everything (documents, menus, indices) is

represented to the user as a hypertext object in HTML format. Hypertext links refer to other documents by their URLs.

These can refer to local or remote resources accessible via FTP, Gopher, Telnet or news, as well as those available via the http protocol used to transfer hypertext documents.

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60What is the World Wide Web?

The client program (known as a browser), e.g. NCSA Mosaic, Netscape Navigator, runs on the user's computer and

provides two basic navigation operations:

to follow a link or to send a query to a server.

A variety of client and server software is freely available.

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A brief history of the Internet.

• ARPANET (50s and 60s, some universities)

• NSFNET (late 70s, all universities)

• TCP/IP (invention ’74) became the official protocol in 1983.

When NSFNET and the ARPANET were connected, the growth became exponential

Many regional networks (Canada, Europe, the Pacific) joined up In mid-80s people began viewing the collection of networks as

the Internet The glue that holds the Internet together is the TCP/IP

reference model and TCP/IP protocol stack

• ANS (Advanced Networks and Service) by MERIT, MCI, and IBM took over NSFNET in 1990 and form ANSNET

• ANSNET sold to American Online in 1995.

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The ARPANET

Growth of the ARPANET (a) December 1969. (b) July 1970. (c) March 1971. (d) April 1972. (e) September 1972.

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Figure 1.13 Hierarchical organization of the Internet

•End users to be connected use the services of Internet Service Provider (ISP)

NAP = Network Access Point to the Internet Backbonein major cities,is the complex switching stations.Speed: up to 600 Mbps

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64Figure 1.13 Internet today

NAP = Network Access Point to the Internet Backbonein major cities,is the complex switching stations.Speed: up to 600 Mbps

•End users to be connected use the services of Internet Service Provider (ISP)

There are local, regional, national, and international Internet service providers (ISPs).

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EO - End OfficePSTN – Public Switching Telephony NetworkPBX – Private Exchange Switch

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1.4 Protocols and Standards1.4 Protocols and Standards

•Protocols •Set of rules that governs data communication•Key elements:

•Syntax•Structure or format – order in which they are presented

•Semantics•Meaning of each section of bits

•Timing•What data and how fast they can be sent not to overload a receiver.

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A standard provides a model for development that enables a product to work regardless of the individual manufacturer

Standards are essential in: i. Creating competitive markets for

equipment manufacturers ii. Guaranteeing national and international

interoperability and compatibility

1.4 Standards1.4 Standards

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De Facto (by fact) standards Proprietary Nonproprietary

De Jure (by law) standards read: dyzuri

1.4 Standards Categories1.4 Standards Categories

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Standards Organizations The ISO, ITU-T (previously CCITT), ANSI, IEEE, and EIA

are some of the organizations involved in standards creation.


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Forum Consist of representatives from

interested corporations Present their conclusions to the standards

bodies Facilitate standardization process

Frame Relay Forum ATM Forum and Consortium Internet Society (ISOC) and Internet Engineering Task Force (IETF)


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Forum are special-interest groups (work with

universities and users), that evaluate and standardize new technologies.

Internet Standards Is a thoroughly tested specification that is

useful to and adhered to by those who work with the Internet

First an Internet draft is published as a Request For Comment (RFC)

is an idea or concept that is a precursor to an Internet standard.


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ISO (International Standards Organization) 1946 – vast number of subjects

89 countries 13000 standards ISO is a member of ITU-T Documents are:

Draft Draft International International Standard

ANSI (American National Standards Institute) Private, nongovernmental, nonprofit organization

NIST (National Institute of Standards and Technology) – a part of the US Dept of Commerce

IEEE (Institute of Electrical and Electronics Engineering)

Largest professional organization in the world ITU-T International Telecommunications Union -

Telecommunications Standardization Sector (former CCITT) – 3000 recommendations


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ISO ISO 8877—Interface in Integrated

Services Digital Network (ISDN) ISO 3309—HDLC frame structure ISO 8028—X.25 packet level protocol


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ITU-T V.32: Defines data transmission over

phone lines X.25: Defines transmission over public

digital networks I.430: Define physical layer

specifications for an interface


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ANSI X3. 23-1985 Programming language

COBOL SONET Synchronous Optical Network ISDN Integrated Services Digital

Network


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IEEE IEEE 802.3: CSMA/CD LAN IEEE 802.4: Token Bus LAN IEEE 802.5: Token Ring LAN


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EIA EIA-232: A 25-pin interface standard EIA-449: Specifies a 37-pin connector

and a 9-pin connector EIA-530: Defines a 25-pin connector


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Federal Communication Commission (FCC) Authority for interstate and

international traffic Reviews communication services and prices Reviews technical specs of communication

hardware Assigns carrier frequencies for radio and

television

Public Utility Commission (PUC) Authority for intrastate traffic

1.4 Regulatory Agencies1.4 Regulatory Agencies

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79IP AddressDownload and install free utility. Run it from Start => All Programs =>

VisualRoute 2009 – Lite Edition or from Internet Explorer under Tools

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80IP Address Each device connected to the Internet

has a unique numeric IP address.

These addresses consist of a set of four groups of numbers, called octets. 66.94.234.13 will get you Yahoo! Use

ping 66.94.234.13 ping yahoo.com tracert yahoo.comas exercises

Your IP can be found here http://myip.dk/

exercises