Data Communication and Networking Fundamentals

7/29/2019 Data Communication and Networking Fundamentals

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Introduction to IT Concepts

Labanan Subion Trillanes

Chapter Objectives:

At the end of the chapter, learners should be able to:

1. Know the basic network communication fundamentals.

2. Know the latest in network communication technology.

3. Know how to connect and share internet connectivity.

1. Know the different computer threats related to network communication.

BriefContent:

Lesson 1: Networking Fundamentals

a. Computer Networks

b. Structure of the OSI Model and Benefits

Lesson 2: Network Architecture

a. Decentralized and Centralized Network Architecture

b. Types of Networks

Lesson 3: Network Components

a. Networking Topologies

b. Networking Standards

c. Networking Devices and Equipments

Lesson 4: Wireless Networking and Broadband Technology

a. Wireless Networking Fundamentals

b. Broadband Technology Fundamentals

c. Types of Broadband Access

Lesson 5: Computer Security Issuesa. Computer Threats and Viruses

b. Computer Safeguards and Security Solutions

Chapter 2 Computer Networks and Security


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Labanan Subion Trillane

LESSON 1: NETWORKING FUNDAMENTALS

The history of computer networking

started in the advancement of telecommunication

systems. Calculations machine communication in

the earlier years was nearly impossible but in the

late 19th century, it was made possible by

ARPANET, the first operational network

developed by DARPA of the United States

Department of Defense. Today, computer

networking is the core of modern communication

system.

A. COMPUTER NETWORKA computer network is simply a connection between two or more computers that are

physically connected to one another so they may be able to communicate. Below is a summary of

the main functions of computer networking.

NETWORKING FUNCTIONS DESCRIPTION

Sharing of Resources Computer networking enables the sharing of resources such as

programs, applications and hardware devices which is effective to

reduce costs and also improves the efficiency of work.

Exchange of Information Computer networking enables the exchange of information where it ismade possible to exchange text and voice data, and multimedia

content such as videos and images.

In computer networking, it is important to consider the following:

Speed Cost Security


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Availability Scalability Reliability

B. THE STRUCTURE OF OPEN SYSTEM INTERCONNECT (OSI)

Figure 3.2.1-1: System Unit

The OSI (Open System Interconnect), is networking standard developed by the

International Standard Organization (ISO) that defines the interoperability and between devices

and software. The OSI model is used as a reference for teaching network communication conceptas shown in the figure. Below is a summary of the different layers of the OSI model and its

description.

OSI LAYER DESCRIPTION

[7] Application Layer that defines the syntax and language used by programs to communicate with

other programs in a computer system.

[6] Presentation Layer that manages the way data are represented and encoded when transmitted.

[5] Session Layer that provides communication coordination in an orderly manner in either one-wayor two-way communication.

[4] Transport Layer that is responsible for the validity and integrity of transmission.

[3] Network Layer that establishes the route between the sender and receiver.

[2] Data Link Layer that is responsible for the node-to-node validity and integrity of data transmission.

[1] Physical Layer that is responsible for passing data onto and receiving them from a connection


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ARPANET Advance Research Project Agency Network is the first

operational network developed by DARPA of theUnited States Department of Defense.

DARPA Defense Advance Research Project Agency is amilitary agency of United States Department ofDefense that fathered the development of Internetand computer networking.

Computer Network is simply a connection between two or morecomputers that are physically connected to oneanother so they may be able to communicate.

OSI (Open System Interconnect) is networking standard developed by the InternationalStandard Organization (ISO) that defines theinteroperability and between devices and software.

ISO (International Standard Organization) is the worlds largest organizing body that formulates,develops and publishes international standards.

1. The history of computer networking started in the advancement of telecommunication systems.

2. Calculations machine communication in the earlier years was nearly impossible but in the late 19 thcentury, it was made possible by ARPANET, the first operational network developed by DARPA ofthe United States Department of Defense.

3. A computer network is simply a connection between two or more computers that are physicallyconnected to one another so they may be able to communicate.

4. Computer Networking have to main functions namely Sharing of Resource (enables the sharingof resources such as programs, applications and hardware devices which is effective to reducecosts and also improves the efficiency of work.) and Exchange of Information (enables the

exchange of information where it is made possible to exchange text and voice data, and multimediacontent).

5. The OSI (Open System Interconnect), is networking standard developed by the InternationalStandard Organization (ISO) that defines the interoperability and between devices and software.

6. The OSI Model is subdivided into 7 Layers namely Application, Presentation, Session, Transport,Network, Data Link, and Physical Layer.

medium such as cables.

Terminologies to Remember:

Lesson Summary:


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LESSON 2: NETWORK ARCHITECTURE

Network Architecture is the overall design of

a communication network. It is a framework used to

specify the networks physical component, functional

configuration, operational principles and procedures.

Network architecture provides assistance or guidelines

used to implement high quality network communication

and also used to assist network activities such as

troubleshooting, security management, and disaster

recovery.

Network architectures are classified according to the way in which they are controlled and

manipulated. There are two ways to control and manipulate computers in a network, these are decentralized

or centralized.

A. DECENTRALIZED AND CENTRALIZED NETWORK ARCHITECTURE

DECENTRALIZED ARCITECTURE

A type of network architecture that directly communicates with every other node in a

computer network. P2P (Peer-to-Peer) is an example of this type of network architecture. P2P

refers to a computer network that allows sharing of resources and information without a central

server. Computers connected in P2P can act as a client or server for the other computers in a

network.

Figure 3.2.2-1: Peer-to-Peer Network

ADVANTAGES DISADVANTAGES

Less Expense No central repository

Easy Setup No Security

Independence


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CENTRALIZED ARCHITECTURE

A type of network architecture that provides central network control and allows user to

simultaneously share the same resources available from it central repository called the server.

There are two important roles in centralized computer network architecture; these are the

client and the server. Client(s) are individual workstations used to accomplish task and

specific requests by the user. A Serveris a computer that provides information or resources to

the client computers on the network. An example of this kind of networking architecture is the

Internet. Once the user connects to the Internet through its workstation by using a web

browser, it is functioning as a client computer. Once connected, the server, serves up

information displayed in your browser.

Figure 3.2.2-2: Centralized Network

B. TYPES OF NETWORKS

Network architectures can also be classified according to the way they are connected and

the range of its coverage. Below are the other types of network architectures.

LAN (LOCAL AREA NETWORK)

Characteristics:

A computer network that is mostly confined to

a single building or group of buildings.

Uses Peer-to-Peer or Client-Server

architecture. Can be wired or wireless.

Capable of transmitting data at very fast rates

compare to WAN.

Figure 3.2.2-3: Local Area Network

ADVANTAGES DISADVANTAGES

Centralized Expense

Scalability Maintenance

Flexibility Dependence

Interoperability

Accessibility


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WAN (WIDE AREA NETWORK)

Characteristics:

A computer network that spans a large

geographical area.

Consists of two or more LANs.

Uses routers and public communication links.

Mostly built by particular private organizations

or ISPs.

The biggest WAN example is the Internet.

Figure 3.2.2-4: Wide Area Network

PAN (PERSONAL AREA NETWORK)

Characteristics:Is a computer network used for communication

among computer devices which are close to one person

such as mobile phones and personal digital assistants

(PDA). Personal Area Network may be wired (using

USB cables) and wireless (using IrDA or Bluetooth

technology).

Figure 3.2.2-5: Personal Area Network

MAN (METROPOLITAN AREA NETWORK)

Characteristics:

Is a computer network that cover a broader

geographical area for communication often uses

transmission facilities provided by telephone

companies.

Figure 3.2.2-6: Metropolitan Area Network

CAN (CAMPUS AREA NETWORK)

A type of computer network that connects two or more LANs limited to a specific

geographical area such as college campus or industrial complex.


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Network Architecture is the overall design of a communication network. It isa framework used to specify the networks physicalcomponent, functional configuration, operational

principles and procedures.

P2P (Peer-to-Peer) refers to a computer network that allows sharing ofresources and information without a central server.

Client(s) in computer networks are individual workstations usedto accomplish task and specific requests by the user.

Server is a computer that provides information or resourcesto the client computers on the network.

LAN (LOCAL AREA NETWORK) is a computer network that is mostly confined to a

single building or group of buildings. Also refers tocomputer network.

WAN (WIDE AREA NETWORK) is a computer network that spans a largegeographical area usually consisting of two or moreLANs.

PAN (PERSONAL AREA NETWORK) is a computer network used for communicationamong computer devices which are close to oneperson such as mobile phones and personal digitalassistants (PDA).

PDA (PERSONAL DIGITAL ASSISTANT) is a mobile device that functions as personalinformation management device.

MAN (METROPOLITAN AREA NETWORK) is a computer network that cover a broadergeographical area for communication often usestransmission facilities provided by telephonecompanies.

CAN (CAMPUS AREA NETWORK) is type of computer network that connects two ormore LANs limited to a specific geographical areasuch as college campus or industrial complex.



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1. Network Architecture is the overall design of a communication network. It is a framework used tospecify the networks physical component, functional configuration, operational principles andprocedures.

2. Network architecture provides assistance or guidelines used to implement high quality networkcommunication and also used to assist network activities such as troubleshooting, securitymanagement, and disaster recovery.

3. Network architectures are classified according to the way such as Decentralized Network (A typeof network architecture that directly communicates with every other node in a computer networkthat allows sharing of resources and information without a central server.) and CentralizedNetwork (A type of network architecture that provides central network control and allows user tosimultaneously share the same resources available from it central repository called the server.) inwhich they are controlled and manipulated.

4. Centralized Network architecture have two major component, the Client (are individualworkstations used to accomplish task and specific requests by the user) and the Server (acomputer that provides information or resources to the client computers on the network).

5. Computer Network architecture can also be classified according to its range or geographicalcoverage of communication such LAN (Local Area Network), MAN (Metropolitan AreaNetwork), PAN (Personal Area Network), CAN (Campus Area Network) and WAN (Wide AreaNetwork).

6. Local Area Network is computer network that is mostly confined to a single building or group ofbuildings. Can be wired or wireless and Capable of transmitting data at very fast rates compare toWAN. A typical setup of this network is used in homes and offices.

7. Metropolitan Area Network is a computer network that cover a broader geographical area forcommunication often uses transmission facilities provided by telephone companies. A typical setupfor this network is used in branch offices.

8. Personal Area Network is a computer network used for communication among computer deviceswhich are close to one person such as mobile phones and personal digital assistants (PDA).Personal Area Network may be wired (using USB cables) and wireless (using IrDA or Bluetoothtechnology). A typical setup of this network is used for short distance sharing and exchanging ofinformation such as photo sharing.

9. Campus Area Network is a type of computer network that connects two or more LANs limited to a

specific geographical area such as college campus or industrial complex.

10. Wide Area Network is a type of computer network that spans a large geographical area consistingof two or more LANs. It uses routers and public communication links mostly built by particularprivate organizations or ISPs. A typical setup of this network is the Internet.

Lesson Summary:


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LESSON 3: NETWORK COMPONENTS

In order to fully build a high quality computer network, it is necessary to understand the different

networking components such as networking equipments and devices, transmission media and network

connections.

A. NETWORKING TOPOLOGY

Topology in network communication is the layout or pattern on how computer are interconnected

to each other. Computers connected in a network can be physically (how computers are connected) or

logically (method used to pass information) patterned using topology.

BUS

A type of computer network topology in

which client devices or computers are

connected via a shared communication line

called bus.

Figure 3.2.3-1: Bus Topology Architecture

Advantage(s):

Failure of one device does not affect the overall network.

Allows a high rate of data transmission.

Easy to implement and extend.

Disadvantage(s):

Limited cable length and number of devices can be handled.

Performance of data transmission is degraded when new devices are attached. A break in cable (bus) can disable the entire network.


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STAR

A type of computer network topology in

which devices and client computers are

connected to a line concentration devices

called hub or switch. This network

architecture is commonly used in home or

office networking.

Figure 3.2.3-2: Star Topology Architecture

Advantage(s):

Problems can easily be identified and troubleshoot.

Easy to implement, manage and extend.

Disadvantage(s):

Fully dependent on a concentration device.

Requires more cable length and may lessen the performance if cable lengths are

long.

Expensive due to the use of concentration devices.

RINGA type of computer network topology in

which devices and client computers are

connected on a single path of transmission

forming a ring.

s

sFigure 3.2.3-3: Ring Topology Architecture

Advantage(s):

Performs better under a high network load.

Disadvantage(s):

One malfunction device or workstation can disable the entire network


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MESH

A type of computer network topology that is

a combination of a ring and a star topology

but does not have any concentration

devices attached. The Internet works

employs the Mesh Topology. Data can

travel in the shortest and easiest route to

reach its destination.

Figure 3.2.3-4: Mesh Topology Architecture

Advantage(s):

Can be expanded without disruption to current user in the network.Disadvantage(s):

Requires more cables than other topologies.

Implementation is complicated.

TREE

A type of computer network topology that is a full

combination of bus and star topology which branch

out the network in many ways. This type of networkarchitecture helps a branch or office to identify its

relevant system in their own network and yet

connected to a bigger network.

Figure 3.2.3-5: Tree Topology Architecture

Advantage(s):

All devices or client computer can access to the larger and their immediate network.

Topology commonly used in branched out networks.

Supported by network and hardware vendors.

Disadvantage(s):

Difficult to configure and Implementation is complicated.

Dependent on the trunk called Backbone.


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B. NETWORKING STANDARDS

There are various networking standard developed by IEEE and ISO each specifying a

certain a type of network cable, topology and access control to used in designing and implementing

network communication. Ethernet is the common networking standard.

ETHERNET Standards

Ethernet is the most popular international standard specification for computer networking.

It was jointly developed and formulated by DEC, Intel, Xerox and the IEEE Committee. Below

is a table that summarizes the different types of Ethernet Standards.

Type Standards Speed Length Topology Cable Application

Ethernet

10BASE5 10Mbps 500m BusCoaxial

(10mm)Connects

computers10BASE2 10Mbps 185m BusCoaxial

(5mm)

10BASE-T 10Mbps 100m Star Twisted-Pair

FastEthernet 100BASE-TX 100Mbps 100m Star Twisted-Pair Connects

high-speed

computers100BASE-FX 100Mbps 2km Star Fiber Optic

GigabitEthernet

1000BASE-T 1000Mbps 100m Star Twisted-Pair

Backbone

1000BASE-CX 1000Mbps 25m Star Twisted-Pair

1000BASE-LX

1000Mbps 550m

Star

Multi-Mode

Fiber Optic

1000Mbps 5kmSingle-Mode

Fiber Optic

1000BASE-SX 1000Mbps 550m Star

Multi-Mode

Fiber Optic

Due to the recent demand for increase in network capacity and speed in handling more

data such as voice and image, Fast Ethernet and Gigabit Ethernet Standards are being used

for faster performance and faster speed.


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OTHER NETWORK STANDARDS

StandardsStandards

Organization

Transmission

Media

Speed Characteristics

FDDI

(FiberDistributedDataInterface)

ANSI

(America

National

Standard

Institute)

Fiber Optic Cable 100Mbps

A dual ring

topology that is

capable of

communicating

even if there are

interruptions in the

network cable.

WirelessNetworking

IEEE 802.11

CommitteeRadio Waves 1-540Mbps

A standard for

wireless

communication

providing freedom

of movement.

Figure 3.2.3-7: FDDI Patch cord

Figure 3.2.3-6: An FDDI Structure


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C. NETWORKING DEVICES AND EQUIPMENTS

Network equipments and devices required to build a computer network is summarized

below.

Equipments Image Characteristics

LAN Boards

(Transceivers)

An expansion card or adapter card that is used

for connecting personal computer to a

network. It is also known as the LAN Card or

the NIC (Network Interface Card).

Relay Devices

A network communication device used

primarily to expand the network coverage of

computer networks.

Cables

A transmission media used for connecting

computers and equipment that connects to a

LAN.

NIC (Network Interface Card)

Network Adapters are devices connected to or installed in network nodes that enable the

nodes to communicate with each other and to access the network. Some network adapters

take the form of external devices that plug into an available USB port and other network

adapters are installed inside computers and peripherals as expansion cards. These adapters

are referred to as network interface cards (NICs).


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RELAY DEVICES

Relay Devices are devices used mainly to expand the network. It helps data flow possible

in the entire network. Below is a summary of the various types of relay devices.

Device Image Networking Symbol Characteristics

Hub

A device that is a common

connection point for devices in a

network.

Repeater

A device that is used to replicate

and regenerate signals, and extend

the range of the network beyond the

allowable length of transmission

media.

Switch

A device that is used to filter and

forward data packets between

transmission media.

Bridge

A device that is used to connect two

or more networks having two the

same transmission media in the

same network.

Router

A device that is used to forward data

packets along networks.


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HUB

o A common connection point for devices in a network.

o Works at Physical Layer of the OSI Layer.

o Broadcasts a packet once arrived at one port.

o Broadcast feature causes network congestion.

o In reality, hub is a repeater with multiple ports.

Advantages:

Cheap

Can connect different media types.

Disadvantages:

Extends the collision domain.

Cannot filter information.

Broadcasts packets to all connected segments.

REPEATER

o A network device used to regenerate or replicate a signal.

o Works at Physical Layer of the OSI Layer.

o Allows the connection of network segments.

o Extends the network beyond the maximum length of a single segment.

o Connects segments of the same network, even if they use different media.

o Relays messages to its original quality.

Advantages:

Can connect different types of media.

Can extend a network in terms of distance.

Does not increase network traffic.

Disadvantages:

Extends the collision domain. Cannot filter data.

Cannot connect different network architecture.

Limited number only can be used in network.


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SWITCH

o A device that filters and forwards packets between LAN segments.

o Works at Data Link Layer and sometimes at the Network Layer of the OSI Layer.

o Supports any packet protocol.

o Acts like a Hub, but filters like a Bridge.

o Keeps track of MAC Addresses of all attached devices.

Advantages:

Limits the collision domain.

Can provide bridging.

Can be configured to limit broadcast domains.

Disadvantages:

More expensive than a Hub or a Bridge.

Configuration of additional functions can be very complex.

BRIDGE

o A device that connects two LANs, or two segments of the same LAN.

o Works at Data Link Layer of the OSI Layer.

o Filters packets. Does not forward packets right away by examining the MAC

Address.

o Forwards packets whose destination address is on a different segment from its

own.

o Divides a network into multiple collisions, so reducing the number of collisions.

o Uses a Spanning Tree Protocol to decide whether to pass a packet on to a

different network segment.

Advantages:

Limits collision domain.

Can extend network distances. Can connect to different types of media and architectures.

Disadvantages:

Broadcast packets cannot be filtered.

More expensive than a repeater.

Slower than a repeater due to additional processing of packets.


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ROUTER

o A device that forwards packets along networks.

o Works at Network Layer of the OSI Layer in an intelligent manner.

o Connects two or more networks (e.g. LANs, MANs, WANs, ISPs).

o Located at gateway or could be the gateway itself.

o Serves as NAT/Firewall for the network.

o Uses headers and forwarding tables to determine the best path for forwarding

the packets.

o Uses protocols to communicate with other.

Advantages:

Limits collision domain.

Can function in LAN or WAN.

Connects differing media and architectures.

Can determine the best path for packets.

Can filter broadcast.

Disadvantages:

Expensive

Must use routable protocols.

Can be difficult to configure its routing.

Slower than a Bridge.

CABLES

All network nodes (computers and peripherals) are connected to each other and to

the network by transmission media. A transmission medium establishes a communications

channel between the nodes on a network and can take several forms:

1. Networks can use existing wiring to connect nodes.2. Wireless networks use radio waves instead of wires or cable to connect nodes.


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In order for computers and peripheral devices to be connected in a computer network,

network cables are being utilized. Below is a summary of the several types of transmission

media.

Transmission

Media Image Characteristics

CoaxialCable

A cable that is composed of copper core

surrounded by an insulating layer. This

type of cable is resistant to external

noise.

Twisted-PairCable

A cable that is composed of several

pairs of copper cores and are twisted inpairs.

Fiber

OpticCable

A cable that is composed of quartz glass

or plastic fiber, which makes the cable

thin and lightweight. This type of cable

can transmit signals without

deterioration. It supports a wider rangeof transmission speed ranging from

10Mbps to 1Gbps.

RadioWaves

A transmission media that uses radio

waves to transmit and receive data

packets used in wireless networking

technology.


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Topology is the layout or pattern on how computer areinterconnected to each other.

Bus is a form of communication line used for exchangingdata. It also refers to the path of transmission.

Star is a type of computer network topology in whichdevices and client computers are connected to lineconcentration devices

Ring is a type of computer network topology in whichdevices and client computers are connected on asingle path of transmission forming a ring

Mesh is a type of computer network topology that is a

combination of a ring and a star topology but does nothave any concentration devices attached

Tree is a type of computer network topology that is a fullcombination of bus and star topology which branchout the network in many ways.

Backbone is a part of computer networking infrastructure used toprovide connection between workstations of differentnetworks.

IEEE Institute of Electrical and Electronics Engineer is a

non-profit association that develops, formulate andestablish electronic standards.

ANSI (America National Standard Institute) non-profit organization that develops, formulate andestablish consensus standards

Ethernet is the most popular international standardspecification for computer networking

FDDI (Fiber Distributed Data Interface) is a networking standard that uses fiber optic cablesfor data transmission.

Network Adapters are devices that enable the nodes to communicatewith each. These adapters are referred to as networkinterface cards (NICs).

Relay Devices are devices used mainly to expand the network. Ithelps data flow possible in the entire network.



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1. Topology in network communication is the layout or pattern on how computer are interconnectedto each other. Computers connected in a network can be physically (how computers areconnected) or logically (method used to pass information) patterned using topology.

2. Basic Computer Topologies are Bus (client devices or computers are connected via a sharedcommunication line), Star (devices and client computers are connected to a line concentrationdevices), Ring (devices and client computers are connected on a single path of transmissionforming a ring), Mesh (is a combination of a ring and a star topology but does not have anyconcentration devices attached) and Tree (is a full combination of bus and star topology whichbranch out the network in many ways).

3. Networking standard developed by IEEE and ISO specifies a certain a type of network cable,topology and access control to be used in designing and implementing network communication.

4. Ethernet is the most popular international standard specification for computer networking. It was

jointly developed and formulated by DEC, Intel, Xerox and the IEEE Committee. Ethernet havethree standards which determine the transmission speed of networking namely the Ethernet, FastEthernet and Gigabit Ethernet.

5. Other networking standards are the FDDI (Fiber Distributed Data Interface - topology that iscapable of communicating even if there are interruptions in the network cable) and WirelessNetworking (standard for wireless communication providing freedom of movement).

6. Network communication equipments and devices required to build a computer network are LANBoards (devices connected to or installed in network nodes that is used to communicate), RelayDevices (devices used mainly to expand the network and helps data flow possible in the entirenetwork) and Cables or Transmission Medium (transmission medium or channel used to

establishes a communications between the nodes in a network and can take several forms).

7. Relay Devices are devices used mainly to expand the network. These devices are Hub (devicethat is a common connection point for devices in a network), Switch (device that is used to filterand forward data packets between transmission media), Bridge (device that is used to connect twoor more networks having two the same transmission media in the same network), Routers (devicethat is used to forward data packets along networks) and Repeaters (device that is used to extendthe range of data transmission).

8. Transmission Medium is a channel used for connecting devices or peripherals to establishnetwork communication. The common transmission medium are the following, Coaxial (cable thatis composed of copper core surrounded by an insulating layer which is resistant to external noise),

Twisted-Pair (cable that is composed of several pairs of copper cores and are twisted in pairstypically used in LANs), Fiber Optics (cable that is composed of quartz glass or plastic fiber thatsupports wider range of transmission speed) and Radio Waves (transmission media that usesradio waves to transmit and receive data packets used in wireless networking technology).

Lesson Summary:


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LESSON 4: WIRELESS AND BROADBAND TECHNOLOGY

Over the recent years in the advancement oftelecommunication system, Wireless communication hadplayed a vital role in the means of transmitting data in a long

range coverage that are impossible to implement with the useof wires or cables. Wireless technology enabled us to shareinformation and resources in a wider range.

In this lesson, wireless and broadband technologywill be discussed including its fundamentals and the basicapplications of wireless and broadband technology.

A. WIRELESS NETWORKING FUNDAMENTALS

Wireless Fidelity, or Wi-Fi, is a brand namelicensed by the Wi-Fi Alliance to describe wireless LANS(WLAN) based on the IEEE 802.11 family of specifications.

Wi-Fi was developed as a method for mobiledevices, such as laptops and personal digital assistants(PDAs), to connect to corporate LANS or the public Internet.Wi-Fi also allows connectivity in peer-to-peer mode, whichenables devices to connect directly with each other. Inpractice, Wi-Fi provides a wireless bridge to Ethernet LANs

and the public Internet.

Basic Wi-Fi Operation

A Wi-Fi network contains one or more Access Points (APs). The area in which clients arein range of the radio signal of the APs is commonly called a hotspot. APs are identified by clientsby their Service Set Identifier (SSID), which is periodically broadcast by the AP. A client initiates aconnection with the AP, which may or may not be accepted depending upon what connectioncriteria have been set. Various degrees of security and encryption can be used over the wirelessconnection. Most APs serve as bridges to an Ethernet LAN, converting Ethernet frames to 802.11frames for transmission over the radio.

Figure 3.2.4-1: Basic Wireless LAN Structure


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WLAN Topologies

Below is a summary of the Wireless LAN Topology.

WLAN Standards

Below is a summary of the Wireless LAN Standards.

Topology Image Characteristics

AdHoc

Also referred to as Peer-To-Peer

Mode or Independent Basic Service

Set (IBSS).

Wireless devices communicate

directly with each other.

Doesnt use Access Points.

Useful for establishing a network

where wireless infrastructure does

not exist or where services are not

required

Infrastructure

An Access Point is present for

wireless devices to communicate

with each other referred to as a

Basic Service Set (BSS).

Two or more BSSs that form a

single subnetwork is called an

Extended Service Set (ESS)

Standard Frequency Speed Security Pros, Cons and Characteristics

IEEE

802.11

2.4 GHZ 1 - 2 Mbps WEP, WPA Specifications have been extended

to 802.11b.


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IEEE802.11a

5 GHZ 25 - 54 Mbps WEP, WPA -8 available channels

-Less potential RF Interference

-Supports multimedia voice, videoand large image application better

than 802.11b

-Shorter range than 802.11b

-Not interoperable with 802.11bIEEE802.11b

2.4 GHz 5 - 11 Mbps WEP, WPA -Not interoperable with 802.11a

-Requires fewer APs than 802.11afor coverage of large area.

-High speed access to data at up to300 ft. from AP

-14 available channels, 11 channelscan be used in the US due to FCCregulation

-3 non-overlapping channels

IEEE802.11g

2.4 GHz 25 - 54 Mbps WEP, WPA -Improve security enhancementsover 802.11

-Compatible with 802.11b

-14 available channels, 11 channelscan be used in the US due to FCCregulation

-3 non-overlapping channels

IEEE802.11n

2.4 GHZ Up to 200Mbps

WEP, WPA -Compatible with 802.11b and802.11g but less throughput

-Uses technology known as MIMO

-Do Spatial Multiplexing techniquefor increased data throughput

Supports multimedia voice, videoand large image application betterthan any 802.11x device


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Advanced WLAN Standards

IEEE 802.11f - Inter Access Point Protocol

The protocol is designed for theenforcement of unique association

throughout an Extended Service Set andfor secure exchange of station's securitycontext between the current AP and thenew AP during the handoff period.

Figure 3.2.4-2: IEEE 802.11f Structure

IEEE 802.11e Wireless Multimedia

It offers quality of service (QoS)

features, including the prioritization of data,voice, and video transmissions.

802.11 is an IEEE standard thatallows devices such as laptop computersor cellular phones to join a wireless LANwidely used in the home, office and somecommercial establishments.

Figure 3.2.4-3: Wireless Multimedia Structure

WLAN Basic Requirements

The following are the basic wireless components used to build and setup a wirelesscommunication network.

A wireless LAN Card or wireless PCMCIA for workstations An Access Point A good wireless link or signal Security

Figure 3.2.4-4: Wireless Network Devices


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Factors Affecting the WLAN Range

Although access points can transmit signals up to 60 feet away in an area with manywalled barriers or as much as 500 feet away in a large open area, the range is affected by thefollowing factors:

Building materials such as steel and drywall can shorten the range of the radio signals. Physical layout of the area can interfere with the signals and cause them to be dropped. Electronic noise from cell phones, microwave ovens, or other devices on the same

frequency can interfere with the transmission of the signals. Range is inversely proportional to data rate, so the faster that the signals are sent, the

less distance they will travel.

B. BROADBAND TECHNOLOGY FUNDAMENTALS

Definitions:

It is a fast connection to the Internet that is always on.

It means sending and receiving data and information of up to 40X faster than a standarddial-up connection.

It is the Information Superhighway. High quality audio and video are possible unlike in dial-up connection.

Figure 3.2.4-5: Wireless Broadband Technology

Benefits of Broadband Technology

Broadband technology offers a wide range of benefits as listed below.

Benefits

Increase usage of the Internet.

Enhances businesses.


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Promotes the development of Information Technology companies.

Facilitates E-Government.

Encourages telecommuting.

Enriches education and integrated learning.

Promotes tourism.

Allows teleconferencing.

Permits telemedicine.

Stimulates E-Commerce.

Allows entertainment and other creative content.

Makes more accessible the vast amount of information and media

content on the Internet.


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C. TYPES OF WIRELESS BROADBAND ACCESS

Below is a summary of the wireless broadband architecture and its characteristics.

WIRED BROADBAND ACCESS

DSL (Digital Subscriber Line)

Works by splitting existingtelephone line signal into two (voiceand data) Mostly asymmetric Mostly up to 1.5 Mbps but canoffer up to 8 Mbps Distance-sensitive therefore notavailable everywhere

Cable

Works by splitting existing cableline signal into two (video and data) Internet speed is just like DSL mostly bundled with cable TVservice though not distant sensitive, butlimited on areas cover

Fiber Optics

higherbandwidth is offered compare to DSL or Cable less susceptible to interference Thinner and lighter Data can be transmitted digitally

BPL (Broadband Power Line) or Power Line Internet

Internet transmitted over utility power lines. Two main categories: In-house and

Access From 256 Kbps to 2.7 Mbps speedon In-house.


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WIRELESS BROADBAND ACCESS

Satellite

Location sensitive Currently, it is slower in both uplink and downlink

Viable option for remote areas

3G (Third Generation)

Works in wireless air interfaces Mobile Internet connection Up to 384 Kbps when stationary or moving inpedestrian speed, up to 128 Kbps when in car,and up to 2 Mbps in fixed application

Wi-Fi (Wireless Fidelity) For laptops with wireless cards, PDAs, etc.

Works in 2.4 GHz and 5 GHz carrier Several standards are implemented Prone to interference

Fixed Wireless

Situated in fixed location (home or office) Also uses 2.4 GHz and 5 GHz carrier frequency Point-to-point transmission uses air as medium Does not require satellite feeds or local phoneservice Cheap, fast Internet and multimedia access through radio links

WiMAX (Worldwide Interoperability for Microwave Access)

Based on IEEE 802.16 standard, alsocalled Wireless MAN. Types of WiMAX: 802.16-2004 (fixedWiMAX) and 802.16-2005 (mobile WiMAX) Maximum bandwidth to offer is 70 Mb Bandwidth throughput depends ondistance (50 km is the maximum)


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Wireless Fidelity (Wi-Fi) was developed as a method for mobile devices, suchas laptops and personal digital assistants (PDAs), toconnect to corporate LANS or the public Internet.

APs (Access Point) is a device used wireless network managementusually a router with wireless capability.

Hotspot is the area in which clients are in range of the radiosignal of the APs.

SSID (Service Set Identifier) are identifier used access point used to identifywireless device

WLAN (Wireless LAN) is a wireless network infrastructure for connectingvarious wireless enabled devices.

Ad Hoc is a wireless network topology for connecting twowireless devices usually in P2P.

Infrastructure is a wireless networking topology used for connectingtwo or more wireless enabled device.

DSL (Digital Subscriber Line) is a type of wired broadband access usually offeredby telephone companies.

BPL (Broadband Power Line) is a type of wired broadband access using electricpower line to provide internet connectivity and

networking capability.

3G (Third Generation) is a type of wireless broadband access provided bymobile phone carriers for internet connectivity.

Fixed Wireless is a type of wireless broadband access provided bymobile phone carriers for internet connectivity using afixed antenna.

WiMAX Worldwide Interoperability for Microwave Access is atype of wireless broadband access used mostly inlarge geographical area also referred as wireless

MAN.



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1. Over the recent years in the advancement of telecommunication system, Wireless communicationhad played a vital role in the means of transmitting data in a long range coverage that areimpossible to implement with the use of wires or cables.

2. Wireless Fidelity, orWi-Fi, is a brand name licensed by the Wi-Fi Alliance to describe wirelessLANS (WLAN) based on the IEEE 802.11 family of specifications. Wi-Fi was developed as amethod for mobile devices, such as laptops and personal digital assistants (PDAs), to connect tocorporate LANS or the public Internet.

3. A Wi-Fi network contains one or more Access Points (APs). The area in which clients are in rangeof the radio signal of the APs is commonly called a hotspot. APs are identified by clients by theirService Set Identifier(SSID), which is periodically broadcast by the AP.

4. Wireless networking can be categorized into two topology namely the Ad Hoc (wireless networktopology for connecting two wireless devices usually in P2P) and Infrastructure (wireless

networking topology used for connecting two or more wireless enabled device).

5. Networking Standards used in wireless LAN are IEEE802.11 (1 - 2 Mbps), IEEE802.11a (25 - 54Mbps), IEEE802.11b (5 - 11 Mbps), IEEE802.11g (25 - 54 Mbps), IEEE802.11n (Up to 200 Mbps),IEEE802.11f(- Inter Access Point Protocol is designed for the enforcement of unique associationthroughout an Extended Service Set and for secure exchange of station's security context betweenthe current AP and the new AP during the handoff period) and IEEE802.11e (Wireless Multimediaoffers quality of service (QoS) features, including the prioritization of data, voice, and videotransmissions).

6. Wireless broadband technology offers a vast benefits from education, to businesses, togovernment, to health care and many more.

7. Wireless broadband is categorized according to the transmission medium it uses and its accessusually categorized into Wired and Wireless Access.

8. Wired Broadband Access can have several form using a wired transmission medium such asDSL (Digital Subscriber Line is a type of wired broadband access usually offered by telephonecompanies), Cable (mostly bundled with cable TV service), Fiber Optics (uses fiber optic cablesthat has large transmission speed), and BPL (Broadband Power Line is a type of broadbandaccess transmitted over utility power lines).

9. Wireless Broadband Access can have several form using a wired transmission medium such asSatellite (Location sensitive and covers a larger geographical area), 3G Third Generation (a type

of wireless broadband access provided by mobile phone carriers for internet connectivity),Wireless Fidelity (a type of broadband access that uses connect to corporate LANs), FixedWireless (Situated in fixed location using fixed antenna) and WiMax (Worldwide Interoperabilityfor Microwave Access is a type of wireless broadband access used mostly in large geographicalarea also referred as wireless MAN).

Lesson Summary:


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LESSON 5: COMPUTER SECURITY ISSUES

In computer networking, one of the major issuesto be concerned and addressed properly is the security ofsharing information and resources. In computer security

threat is a possible danger that might exploit network andcomputer vulnerabilities that can cause harm.

In this lesson, computer threats like securityvulnerabilities and viruses will be discussed accordinglyfollowed by the different safeguards techniques andremedies for such damages caused by an attack.

A. COMPUTER THREATS AND VIRUSES

A computer threat is exactly the same as if someone tries to threaten you but the thing ishappening in a computer system that may be real or a hoax. If a computer threat is a real in naturethis can be a virus, a spyware or a malware that may be destructive to your computer system.

HACKERS

A hacker is defined as anyone who breaks into a computer system (whether anindividual computer or a network) unlawfully. Hackers can gain access to computers directly orindirectly. Direct access involves sitting down at a computer and installing hacking software. Themost likely method a hacker will take to access a computer is indirectly through its Internetconnection. When connected to the Internet, your computer is potentially open to attack byhackers.

TYPES OF HACKERS

o White-Hat Hackers

A type of hacker that breaks into system just for the challenge tothemselves that dont wish to steal information or destroy a computersystem, educated themselves as experts who are performing a servicefor the society be helping companies realize the vulnerabilities thatexists in their systems.

o Black-Hat Hackers

A type of hacker that breaks into system that uses their knowledge todestroy and steal information.

o Script Kiddies

A type of hacker that uses tools created by other skilled hackers topenetrate security vulnerabilities.


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VIRUSES

A computer virus is a computer program that attaches itself to another computerprogram (known as the host program) and attempts to spread it to other computers when filesare exchanged. Viruses normally attempt to hide within the code of a host program to avoiddetection. Viruses, by definition, have a method to spread.

HOW COMPUTERS ARE BEING INFECTED

Figure 3.2.5-1: Computer Virus Infection Method

If a computer is exposed to a file infected with a virus, the virus will try to copyitself and infect a file on your computer. If you never expose your computer to new files, itwill not become infected. However, this would be the equivalent of a human being living ina bubble to avoid catching viruses. Sharing disks is a common source of virus infection,as is e-mail. Just opening an e-mail message will not infect your computer with a virus.Downloading or running a file that is attached to the e-mail is how your computerbecomes infected.


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TYPES OF COMPUTER VIRUSES

o Some viruses are hidden on Web sites in the form of scripts. Scripts are miniprograms that are often used to perform legitimate functions on Web sites.However, some scripts are malicious. For example, say you receive an e-mailencouraging you to visit a Web site full of useful programs and information.

Unbeknownst to you, clicking a link to display a video runs a script that infectsyour computer with a virus.

o Macro virusesare attached to documents (such as Word files) that use macros.A macro is a short series of commands that usually automates repetitive tasks.However, macro languages are now so sophisticated that viruses can be writtenwith them. E-mail viruses use the address book in the victims e -mail system todistribute the virus.

o Trojan Horses enter the computer as legitimate programs chosen for downloadby the user, often as something for free. Attached is hidden code that infects thecomputer once the desired program is loaded. Since they enter at the users

request, virus-detection software often misses them.

CLASSIFICATION OF COMPUTER VIRUSES

Viruses can also be classified by the methods they take to avoid detection byantivirus software:

o Polymorphic viruseschange their own code (or periodically rewrite themselves)to avoid detection. Most polymorphic viruses infect one certain type of file (.exefiles, for example).

o Multipartite viruses are designed to infect multiple file types in an effort to fool

the antivirus software that is looking for them.

o Stealth viruses temporarily erase their code from the files where they reside andhide in the active memory of the computer. This helps them avoid detection ifonly the hard drive is being searched for viruses.

B. COMPUTER SAFEGUARDS AND SECURITY SOLUTIONS

FIREWALLS

Firewalls are software programs or hardware devices designed to keepcomputers safe from hackers. By using a firewall, you can close off open logical ports to

invaders and potentially make your computer invisible to other computers on the Internet.Most Operating Systems installed, also includes a firewall that is simple but reliable touse.

The most popular software firewalls for the home include Norton PersonalFirewall, McAfee Firewall, ZoneAlarm, and BlackICE PC Protection. You can also buy andconfigure hardware firewall devices if opted.


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ANTIVIRUS AND ANTI-MALWARE SOFTWARES

The best defense against viruses is to install antivirus software, which isspecifically designed to detect viruses and protect your computer and files from harm.

Most antivirus software looks for virus signatures in files. Signatures are portions

of the virus code that are unique to a particular computer virus. Antivirus software scansfiles for these signatures and thereby identifies infected files and the type of virus that isinfecting them.

SECURITY SOLUTIONS AND PROTECTION

If youre keeping a wired network secure with a firewall, youre fairly safe frommost hacker attacks. However, wireless networks have wide ranges, including areasoutside of your house. This makes it possible for a hacker to access your network withoutyou even knowing it. Because your packets of information are being broadcast through

the airwaves, a hacker can intercept and decode information from your transmissions thatmay allow him to bypass your firewall.Others may steal your bandwidth and crimes can be committed through your network.Therefore, to secure a wireless network, you should take the following additionalprecautions:

1. Change Your Network Name (SSID): Each wireless network has its own name toidentify it. Unless you change this name when you set up your router, the router usesa default network name that all routers from that manufacturer use. Hackers know thedefault names and access codes for routers.

2. Disable SSID Broadcast: Most routers are set up to broadcast their SSID so other

wireless devices can find them. If your router supports disabling SSID broadcasting,turn it off. This makes it more difficult for a hacker to detect your network.

3. Change the Default Password on Your Router: Hackers know the default passwordsof most routers, and if they can access your router, they can probably break into yournetwork.

4. Turn on Security Protocols: Most routers ship with security protocols such as WiredEquivalent Privacy(WEP) or Wi-Fi Protected Access (WPA). Both use encryption toprotect data in your wireless transmissions. WPA is a stronger protocol than WEP, soenable WPA if you have it; enable WEP if you dont.

5. Implement Media Access Control: Each network adapter on your network has aunique number assigned to it by the manufacturer. This MAC address is a numberprinted right on the network adapter. Many routers allow you to restrict access to thenetwork to only certain MAC addresses.

6. Apply Firmware Upgrades: Your router has read-only memory that has softwarewritten to it. This software is known as firmware. Periodically, as bugs are found in thefirmware, manufacturers issue patches. Periodically check the manufacturers Website and apply any necessary upgrades to your firmware.


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Computer Threat threat is a possible danger that might exploit networkand computer vulnerabilities that can cause harm.

Hacker is defined as anyone who breaks into a computersystem (whether an individual computer or a network)unlawfully.

White-Hat Hacker is a type of hacker that breaks into system just for thechallenge to themselves that dont wish to stealinformation or destroy a computer system

Black-Hat Hacker is a type of hacker that breaks into system that usestheir knowledge to destroy and steal information.

Script Kiddies is a type of hacker that uses tools created by other

skilled hackers to penetrate security vulnerabilities.

Computer Virus is a computer program that is harmful to a computersystem that can destroy files and information.

Scripts are mini programs that are often used to performlegitimate functions on Web sites. However, somescripts are malicious.

Macro is a short series of commands that usually automatesrepetitive tasks.

Firewalls are software programs or hardware devices designedto keep computers safe from hackers.

Antivirus is a computer program that is best suited to protectcomputer system from virus and security threats.



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1. In computer networking, one of the major issues to be concerned and addressed properly is thesecurity of sharing information and resources. In computer security threat is a possible dangerthat might exploit network and computer vulnerabilities that can cause harm.

2. A hacker is defined as anyone who breaks into a computer system (whether an individualcomputer or a network) unlawfully.

3. Hackers can gain access into computer system in two different ways such as Direct Access(involves sitting down at a computer and installing hacking software) and Indirect Access (usuallyusing the internet to exploit computer security).

4. Hackers can be categorized into three types namely White-Hat Hackers (a hacker that breaks intosystem just for the challenge to themselves that dont wish to steal information or destroy acomputer system), Black-Hat Hackers (a hacker that breaks into system that uses their knowledgeto destroy and steal information) and Script Kiddies (a hacker that uses tools created by other

skilled hackers to penetrate security vulnerabilities).

5. Computer virus is a computer program that attaches itself to another computer program (knownas the host program) and attempts to spread it to other computers when files are exchanged.Viruses normally attempt to hide within the code of a host program to avoid detection.

6. Computer virus can be categorized into three types namely Scripts (mini programs that are oftenused to perform legitimate functions on Web sites), Macro Virus (virus attached to a document filethat executes short series of commands that usually automates repetitive tasks) and Trojan Horse(a computer virus that acts as a legitimate program that posses security threats).

7. Computer virus can also be classified according the way it hides to avoid detection. It can be

classified as Polymorphic Virus (change their own code or periodically rewrite themselves toavoid detection), Multipartite Virus (designed to infect multiple file types in an effort to fool theantivirus software)and Stealth Virus (temporarily erase their code from the files where they resideand hide in the active memory of the computer).

8. Computers can be safeguarded using different software and hardware such as the Firewalls (aresoftware programs or hardware devices designed to keep computers safe from hackers that closesopen logical ports to invaders and potentially make your computer invisible to other computers onthe Internet) and Antivirus Programs (the best guard and defense against viruses).

Lesson Summary:

Data Communication and Networking Fundamentals

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