Networking BASICSNetworking BASICS

Introduction to NetworkingIntroduction to Networking

ObjectivesObjectivesDefine a computer network.Define a computer network.

List the four purposes of a network.List the four purposes of a network.

Explain the elements of Explain the elements of communication.communication.

List and describe the two types of List and describe the two types of networks.networks.

What Is a Computer Network?What Is a Computer Network?

A A computer network computer network is computers and is computers and devices connected together.devices connected together.

A single computer is limited to its own A single computer is limited to its own hardware and software.hardware and software.

The capabilities of a computer are The capabilities of a computer are increased when connected with other increased when connected with other devices to form a computer network.devices to form a computer network.

Purpose of a Computer NetworkPurpose of a Computer Network

Summarized in a single word: Summarized in a single word: sharing.sharing.Individual computers are isolated.Individual computers are isolated.Networked computers can share Networked computers can share resources.resources.Three types of resources can be shared.Three types of resources can be shared.Networks also make computer Networks also make computer management easier.management easier.

Share Software and DataShare Software and Data

Application and utility software can be Application and utility software can be shared by all users across the network.shared by all users across the network.

This requires only a single software copy This requires only a single software copy to be purchased and maintained.to be purchased and maintained.

Data files can also be shared.Data files can also be shared.

This makes data more accessible and This makes data more accessible and maintains integrity.maintains integrity.

Share HardwareShare HardwareSharing is an essential feature of a Sharing is an essential feature of a computer network.computer network.This reduces costs and the work of This reduces costs and the work of support staff.support staff.Printers, fax modems, scanners, hard Printers, fax modems, scanners, hard drives, CD-ROMs, and DVDs can all drives, CD-ROMs, and DVDs can all be shared.be shared.

Improve CommunicationsImprove Communications

Communication is essential in today’s Communication is essential in today’s businesses.businesses.Computer networks can help in improved Computer networks can help in improved communications through groupware.communications through groupware.E-mail, electronic calendars, collaborative E-mail, electronic calendars, collaborative writing, and video conferencing are writing, and video conferencing are available.available.

Centralize ManagementCentralize Management

Support staffs are stretched to the limits.Support staffs are stretched to the limits.

Computer networks allow computers to be Computer networks allow computers to be managed from one central location.managed from one central location.

Software updates can be “pushed” to users’ Software updates can be “pushed” to users’ computers.computers.

Problems can be diagnosed over the network.Problems can be diagnosed over the network.

Training can be done over the network.Training can be done over the network.

Types of NetworksTypes of NetworksTwo types of network Two types of network classificationsclassificationsClassified by device that Classified by device that controls networkcontrols networkClassified by distance between Classified by distance between devicesdevices

Peer-to-Peer NetworkPeer-to-Peer Network

No single computer controls No single computer controls the network.the network.

Each computer is the same (a Each computer is the same (a peer) to all others.peer) to all others.

It is suitable for small offices.It is suitable for small offices.

Types of NetworksTypes of Networks

Server-Based NetworkServer-Based NetworkThe network is controlled by a special The network is controlled by a special high-powered server.high-powered server.

The server is dedicated to running the The server is dedicated to running the network.network.

Print and file servers, application servers, Print and file servers, application servers, communication servers, and directory communication servers, and directory service servers are common.service servers are common.

Server-Based NetworkServer-Based Network

Local Area NetworkLocal Area NetworkNetwork computers are located relatively Network computers are located relatively close to each other. close to each other.

They are generally limited to buildings They are generally limited to buildings owned by one organization.owned by one organization.

They operate at high speeds.They operate at high speeds.

They are low-cost networks.They are low-cost networks.

Local Area NetworkLocal Area Network

Wide Area NetworkWide Area NetworkNetwork computers are spread out over a Network computers are spread out over a larger area. larger area. They generally cross public thoroughfares.They generally cross public thoroughfares.They are often managed by public They are often managed by public carriers.carriers.They operate at lower speeds.They operate at lower speeds.They are a higher-cost network.They are a higher-cost network.

Wide Area NetworkWide Area Network

SummarySummaryA computer network is defined as multiple computers A computer network is defined as multiple computers and devices that are all connected together. By and devices that are all connected together. By connecting the computers together, the capabilities of connecting the computers together, the capabilities of each computer are increased so the users can each computer are increased so the users can accomplish more.accomplish more.

The purpose of a computer network is to share. The purpose of a computer network is to share. Application software, utility software, and the data that Application software, utility software, and the data that serves as input into the software can all be shared serves as input into the software can all be shared across a network. Computer hardware can also be across a network. Computer hardware can also be shared on a computer network. Printers, fax machines, shared on a computer network. Printers, fax machines, scanners, modems, hard disk drives, CD-ROM drives, scanners, modems, hard disk drives, CD-ROM drives, and DVD drives are just a few of the hardware devices and DVD drives are just a few of the hardware devices that can be shared across a computer network.that can be shared across a computer network.

Summary (continued)Summary (continued)Computer networks can be important tools that help Computer networks can be important tools that help improve communication between users. A special improve communication between users. A special category of software that assists with communication category of software that assists with communication over a computer network is known as groupware. over a computer network is known as groupware. Groupware refers to programs that help people work Groupware refers to programs that help people work together collectively even if they are located remotely together collectively even if they are located remotely from each other. One of the most common groupware from each other. One of the most common groupware applications used across computer networks is electronic applications used across computer networks is electronic mail, or e-mail. Groupware services also include mail, or e-mail. Groupware services also include electronic calendars, collaborative writing software, and electronic calendars, collaborative writing software, and video conferencing.video conferencing.The communication that takes place between devices on The communication that takes place between devices on a computer network is known as telecommunications. a computer network is known as telecommunications. Telecom-munications is defined as transmitting Telecom-munications is defined as transmitting information over a distance and is generally considered information over a distance and is generally considered to be a two-way transmission of voice, video, or data.to be a two-way transmission of voice, video, or data.

Summary (continued)Summary (continued)Computer networks allow the computers connected to Computer networks allow the computers connected to the network to be managed from one central location. the network to be managed from one central location. Software updates can be “pushed” across the network to Software updates can be “pushed” across the network to all computers, thus eliminating the need for support staff all computers, thus eliminating the need for support staff to visit every office and perform the new installation. to visit every office and perform the new installation. Problem diagnosis can be performed across the Problem diagnosis can be performed across the network. Centralized management can be used for network. Centralized management can be used for training as well.training as well.Computer networks are generally classified two different Computer networks are generally classified two different ways. The first classification of networks involves the ways. The first classification of networks involves the device that actu-ally controls the network. In a peer-to-device that actu-ally controls the network. In a peer-to-peer network, no single high-powered computer controls peer network, no single high-powered computer controls and manages the network. The computers collectively and manages the network. The computers collectively run the network instead of a special dedicated computer run the network instead of a special dedicated computer doing it. These networks are suitable for small offices doing it. These networks are suitable for small offices that need to share a printer or computer data.that need to share a printer or computer data.

Summary (continued)Summary (continued)The second type of network classified by the device that The second type of network classified by the device that con-trols the network is known as a server-based con-trols the network is known as a server-based network. Unlike a peer-to-peer network, a server-based network. Unlike a peer-to-peer network, a server-based computer network is con-trolled by at least one special computer network is con-trolled by at least one special high-powered computer. These special computers are high-powered computer. These special computers are called servers, while the individual com-puters on the called servers, while the individual com-puters on the network are called clients. Servers are usually dedicated network are called clients. Servers are usually dedicated to running the network and do not function as clients. to running the network and do not function as clients. Instead, their sole job is to service requests quickly from Instead, their sole job is to service requests quickly from the network clients and ensure the security of the the network clients and ensure the security of the software and hardware. There are many different types software and hardware. There are many different types of specialized servers.of specialized servers.

Summary (continued)Summary (continued)Networks can also be classified by geography or how Networks can also be classified by geography or how close the devices are to each other. There are two close the devices are to each other. There are two categories of networks based on geography. The first is categories of networks based on geography. The first is a local area network (LAN). A LAN is a computer a local area network (LAN). A LAN is a computer network that has all the computers relatively close to network that has all the computers relatively close to each other. They operate at high speeds for a low cost. each other. They operate at high speeds for a low cost. A wide area network (WAN) transmits over a public A wide area network (WAN) transmits over a public thorough-fare, such as a road, highway, railroad, or body thorough-fare, such as a road, highway, railroad, or body of water. A WAN service must be purchased from a of water. A WAN service must be purchased from a carrier. WANs are managed by the carrier instead of by carrier. WANs are managed by the carrier instead of by the user. Compared to LANs, the cost of WANs is high the user. Compared to LANs, the cost of WANs is high and they operate at a low speed.and they operate at a low speed.

Networking BASICSNetworking BASICS

Network MediaNetwork Media

ObjectivesObjectivesExplain how data transmissions Explain how data transmissions are sent and received.are sent and received.

List and describe the types of List and describe the types of transmission media.transmission media.

Describe the functions of a Describe the functions of a network interface card.network interface card.

Types of NetworksTypes of NetworksThere are two types of There are two types of networks by which networks by which information is transmitted:information is transmitted:– circuit switched networkscircuit switched networks

– packet switched networkspacket switched networks

Circuit Switched NetworkCircuit Switched Network

There is a dedicated and direct physical There is a dedicated and direct physical connection between sender and receiver.connection between sender and receiver.No other transmissions can take place while the No other transmissions can take place while the connection is active.connection is active.Once the transmission is ended, other Once the transmission is ended, other connections can be made with other devices.connections can be made with other devices.It is ideal for voice communications because It is ideal for voice communications because there are no interruptions from other devices or there are no interruptions from other devices or delays. delays.

Packet Switched NetworkPacket Switched Network

This network requires data transmission be broken into This network requires data transmission be broken into smaller units called smaller units called packetspackets..

Each packet is sent independently through the network.Each packet is sent independently through the network.

It is used for data transmission because data is not as It is used for data transmission because data is not as time-sensitive as voice communication. time-sensitive as voice communication.

It allows multiple devices to share one line or frequency. It allows multiple devices to share one line or frequency.

It facilitates error correction. It facilitates error correction.

Transmission MediaTransmission Media

Copper cablesCopper cables

Fiber optic cablesFiber optic cables

WirelessWireless

Copper CablesCopper CablesThin coaxialThin coaxial

Shielded twisted pair (STP)Shielded twisted pair (STP)

Unshielded twisted pair (UTP)Unshielded twisted pair (UTP)

UTP rated by Category 1 - 6UTP rated by Category 1 - 6

Copper CablesCopper Cables

Copper CablesCopper Cables

Fiber OpticFiber OpticThis cable uses a thin cylinder of glass to send This cable uses a thin cylinder of glass to send light impulses. light impulses.

The cable consists of a strand of glass (The cable consists of a strand of glass (core) core) surrounded by a glass tube (surrounded by a glass tube (claddingcladding). ).

Single modeSingle mode - one light source flashes a light - one light source flashes a light down the cable.down the cable.

MultimodeMultimode - supports many simultaneous light - supports many simultaneous light transmissions.transmissions.

Fiber OpticFiber Optic

WirelessWirelessTransmission is sent and received through Transmission is sent and received through invisible wavesinvisible wavesLess expensive than copper or fiber optic lines. Less expensive than copper or fiber optic lines. Allows the user to move freely around the office Allows the user to move freely around the office or campus and still remain connected to the or campus and still remain connected to the networknetworkFastest-growing segment of network media Fastest-growing segment of network media todaytoday

Wireless TransmissionsWireless TransmissionsInfrared transmits data using infrared (IR) light.Infrared transmits data using infrared (IR) light.IR shares many of the same properties as visible IR shares many of the same properties as visible light .light .Radio frequencyRadio frequency signals can be transmitted over signals can be transmitted over radio waves similar to local radio station radio waves similar to local radio station transmissions. transmissions. The signal comes in at a lower power level and The signal comes in at a lower power level and does not reach as far. does not reach as far.

Network Interface CardNetwork Interface CardThe NIC serves as the connection between the The NIC serves as the connection between the personal computer and the network media.personal computer and the network media.

It connects to the computer on its base by It connects to the computer on its base by plugging into an expansion slot of the computer. plugging into an expansion slot of the computer.

Another connection is accessible from the Another connection is accessible from the outside of the computer and has connections for outside of the computer and has connections for the cables to plug into the network. the cables to plug into the network.

Network Interface CardNetwork Interface Card

Changes from parallel to serial Changes from parallel to serial transmissiontransmission

Creates packets Creates packets

Determines when to send Determines when to send

Transmits packet Transmits packet

Network Interface CardNetwork Interface Card

SummarySummarySwitching involves moving (switching) the signal from Switching involves moving (switching) the signal from one wire or frequency to another. A circuit switched one wire or frequency to another. A circuit switched network creates a dedicated and direct physical network creates a dedicated and direct physical connection between the sender and receiver. No other connection between the sender and receiver. No other transmissions can take place while the connection is transmissions can take place while the connection is active, but once the transmission is ended, other active, but once the transmission is ended, other connections can be made with other devices. Circuit connections can be made with other devices. Circuit switching is ideal for voice communications. Computer switching is ideal for voice communications. Computer networks sending data use packet switched networks. networks sending data use packet switched networks. Packet switching requires that the data transmission be Packet switching requires that the data transmission be broken into smaller units called packets. Each packet is broken into smaller units called packets. Each packet is then sent independently through the network to reach then sent independently through the network to reach the destination.the destination.

Summary (continued)Summary (continued)There are many different types of network media, yet they There are many different types of network media, yet they all can be classified into three major categories: copper, all can be classified into three major categories: copper, fiber optic, and wireless. Thin coaxial cable is fiber optic, and wireless. Thin coaxial cable is approximately one-quarter of an inch in diameter, has a approximately one-quarter of an inch in diameter, has a single copper wire at its center, and is surrounded by a single copper wire at its center, and is surrounded by a layer of insulation. Around the insulation is a braided layer of insulation. Around the insulation is a braided copper mesh channel, and everything is covered by a thick copper mesh channel, and everything is covered by a thick outer shield of insulation. Twisted pair cable has become outer shield of insulation. Twisted pair cable has become the standard today for copper cabling used in computer the standard today for copper cabling used in computer net-works, replacing thin coaxial cable. Twisted pair cable net-works, replacing thin coaxial cable. Twisted pair cable is two insulated copper wires that are twisted around each is two insulated copper wires that are twisted around each other. Each pair is then bundled together with other pairs in other. Each pair is then bundled together with other pairs in a jacket. There are two types of twisted pair cables. a jacket. There are two types of twisted pair cables. Shielded twisted pair (STP) cables have a foil shielding on Shielded twisted pair (STP) cables have a foil shielding on the inside of the jacket, which reduces interference. the inside of the jacket, which reduces interference. Unshielded twisted pair (UTP) cables do not have any Unshielded twisted pair (UTP) cables do not have any shielding.shielding.

Summary (continued)Summary (continued)A fiber optic cable uses a very thin cylinder of glass, A fiber optic cable uses a very thin cylinder of glass, instead of copper, at its center. Fiber optic cables send instead of copper, at its center. Fiber optic cables send light impulses instead of transmitting electrical signals. light impulses instead of transmitting electrical signals. Wireless communica-tion uses no visible connection, Wireless communica-tion uses no visible connection, such as a copper cable or fiber optic line, between the such as a copper cable or fiber optic line, between the network devices. Instead, the transmis-sion is sent and network devices. Instead, the transmis-sion is sent and received through invisible waves. Transmission signals received through invisible waves. Transmission signals can be sent by infrared light waves or radio frequency can be sent by infrared light waves or radio frequency waves.waves.

Summary (continued)Summary (continued)When connecting a personal computer to the When connecting a personal computer to the transmission media on a LAN, hardware known as a transmission media on a LAN, hardware known as a network interface card (NIC) is used. A NIC serves as network interface card (NIC) is used. A NIC serves as the connection between the personal computer and the the connection between the personal computer and the network media. The NIC connects to the computer on its network media. The NIC connects to the computer on its base by plugging into one of the expansion slots of the base by plugging into one of the expansion slots of the computer. The other connection, found on the side of the computer. The other connection, found on the side of the NIC, is accessible from the outside of the computer and NIC, is accessible from the outside of the computer and has connections for the cables to plug into the network has connections for the cables to plug into the network (or an antenna for wireless transmissions). These (or an antenna for wireless transmissions). These connections depend on the type of network media being connections depend on the type of network media being used.used.

Networking BASICSNetworking BASICS

Network DesignNetwork Design

ObjectivesObjectivesList and describe the List and describe the characteristics of the mesh, bus, characteristics of the mesh, bus, ring, star, and hybrid topologies.ring, star, and hybrid topologies.Tell what items should be Tell what items should be considered when selecting a considered when selecting a network topology.network topology.

Objectives (continued)Objectives (continued)

Define channel access method.Define channel access method.

Give the advantages and Give the advantages and disadvantages of contention, disadvantages of contention, polling, token passing, and polling, token passing, and demand priority channel access demand priority channel access methods.methods.

TopologiesTopologiesPhysical layout of network Physical layout of network devicesdevices

Four types: mesh, bus, ring, Four types: mesh, bus, ring, and starand star

Mesh TopologyMesh TopologyIt is also called a It is also called a point-to-point point-to-point topology.topology.Each device is connected directly to Each device is connected directly to all other network devices.all other network devices.It provides fault tolerance.It provides fault tolerance.It is only found in wide area networks.It is only found in wide area networks.

Mesh TopologyMesh Topology

Bus TopologyBus TopologyIt is a It is a multipoint multipoint topology.topology.Each device shares the connection.Each device shares the connection.The bus has one starting and one The bus has one starting and one ending point.ending point.Packets stop at each device on the Packets stop at each device on the network.network.Only one device at a time can send. Only one device at a time can send.

Bus TopologyBus Topology

Ring TopologyRing Topology

It is a circle with no ends.It is a circle with no ends.

Packets are sent from one Packets are sent from one device to the next.device to the next.

It does not slow down as It does not slow down as more devices are added.more devices are added.

Ring TopologyRing Topology

Star TopologyStar TopologyAll devices are connected to a central All devices are connected to a central device (hub).device (hub).The hub receives and forwards The hub receives and forwards packets.packets.It is the easiest topology to It is the easiest topology to troubleshoot and manage.troubleshoot and manage.It has a single point of failure. It has a single point of failure.

Star TopologyStar Topology

Hybrid TopologiesHybrid TopologiesThey are variations of two or more They are variations of two or more topologies.topologies.Star busStar bus – used to connect multiple – used to connect multiple hubs in a star topology with a bus. hubs in a star topology with a bus. Star ringStar ring – wired like star, but – wired like star, but functions like a ring.functions like a ring.

Design ConsiderationsDesign Considerations

The best topology involves The best topology involves matching with the environ-matching with the environ-ment it is to be used in.ment it is to be used in.The physical arrangement of The physical arrangement of computers do not dictate the computers do not dictate the necessary topology. necessary topology.

SummarySummaryTopology refers to the physical layout of the network Topology refers to the physical layout of the network devices and cabling and how all the components devices and cabling and how all the components communicate with each other. Computer network communicate with each other. Computer network topology refers to how the computer network is topology refers to how the computer network is arranged. There are four basic types of computer arranged. There are four basic types of computer network topologies: mesh, bus, ring, and star.network topologies: mesh, bus, ring, and star.

A mesh topology is also called a point-to-point topology. A mesh topology is also called a point-to-point topology. Each device is connected directly to all other devices on Each device is connected directly to all other devices on the network. A mesh topology is sometimes used in a the network. A mesh topology is sometimes used in a wide area network (WAN) setting to ensure that all the wide area network (WAN) setting to ensure that all the sites continue to transmit in the event of a cable failure sites continue to transmit in the event of a cable failure or another similar problem. Mesh topologies are rarely or another similar problem. Mesh topologies are rarely used in a LAN.used in a LAN.

Summary (continued)Summary (continued)LANs typically use a multipoint topology in which each computer on LANs typically use a multipoint topology in which each computer on the network has just one connection. This connection is attached to the network has just one connection. This connection is attached to a single cable that is shared by all other devices on the network. a single cable that is shared by all other devices on the network. The most common type of multipoint topology is a bus topology. A The most common type of multipoint topology is a bus topology. A computer network bus topology is characterized by one starting computer network bus topology is characterized by one starting point and one ending point. A bus network topology works well for point and one ending point. A bus network topology works well for smaller networks and is inexpensive to install. However, it can smaller networks and is inexpensive to install. However, it can become slow when more devices are added to the network.become slow when more devices are added to the network.A star topology describes a network in which all the devices are A star topology describes a network in which all the devices are connected to a central device known as a hub, which is respon-sible connected to a central device known as a hub, which is respon-sible for receiving and forwarding packets to other devices on the for receiving and forwarding packets to other devices on the network. Because everything is centralized in a star topology, it is network. Because everything is centralized in a star topology, it is the easiest topology to manage and troubleshoot.the easiest topology to manage and troubleshoot.

Summary (continued)Summary (continued)A multipoint ring topology is the opposite of a bus. A bus has two A multipoint ring topology is the opposite of a bus. A bus has two end points, but a ring is a circle with no ends. All the devices on the end points, but a ring is a circle with no ends. All the devices on the network are connected to the ring. Unlike a bus topology, in which network are connected to the ring. Unlike a bus topology, in which the network devices do not play an active role in the network, each the network devices do not play an active role in the network, each device has additional network functions in a ring topology. A ring device has additional network functions in a ring topology. A ring topology works well for a computer network with many devices topology works well for a computer network with many devices attached to it.attached to it.

Not all topologies are strictly mesh, bus, star, or ring. Some Not all topologies are strictly mesh, bus, star, or ring. Some variations of these topologies, known as hybrid topologies, are also variations of these topologies, known as hybrid topologies, are also used. These variations are actually combinations of two or more used. These variations are actually combinations of two or more topologies. topologies.

Summary (continued)Summary (continued)A star bus topology is typically used to connect multiple A star bus topology is typically used to connect multiple hubs in star topologies with a bus topology and provides hubs in star topologies with a bus topology and provides additional fault tolerance. A star ring topology is wired additional fault tolerance. A star ring topology is wired like a star, but functions like a ring. The packets in a star like a star, but functions like a ring. The packets in a star ring do not go directly to the next device on the ring, but ring do not go directly to the next device on the ring, but instead go to a central hub.instead go to a central hub.

Networking BASICSNetworking BASICS

Network ArchitecturesNetwork Architectures

ObjectivesObjectivesExplain why standards were Explain why standards were developed for LANs.developed for LANs. Give several examples of Ethernet Give several examples of Ethernet architectures.architectures. List the features of a token ring List the features of a token ring network.network. Tell how a wireless LAN functions.Tell how a wireless LAN functions. Provide guidelines for designing a Provide guidelines for designing a network.network.

StandardsStandardsDifferent architectures could restrict Different architectures could restrict the growth of networking.the growth of networking.The Institute of Electrical and The Institute of Electrical and Electronic Engineers (IEEE) Electronic Engineers (IEEE) developed computer network developed computer network architecture standards.architecture standards.There are three dominant standards: There are three dominant standards: Ethernet (802.3), token ring (802.5), Ethernet (802.3), token ring (802.5), and wireless (802.11).and wireless (802.11).

EthernetEthernetEthernet is the most popular LAN architecture Ethernet is the most popular LAN architecture today.today.

It is easy to installIt is easy to install and in and inexpensive. expensive.

Data transmission is broken into packets. Data transmission is broken into packets.

The standard method of labeling different The standard method of labeling different versions is versions is Maximum Speed-Transmission Maximum Speed-Transmission Mode-Segment Length Mode-Segment Length oror Media Type Media Type. .

10Base210Base2It is a bus topology that uses contention It is a bus topology that uses contention (CSMA/CD) and thin coax.(CSMA/CD) and thin coax.

Segments are connected together through Segments are connected together through a repeater. a repeater.

It can connect up to five 200-meter It can connect up to five 200-meter segments using four repeaters (5-4-3 segments using four repeaters (5-4-3 rule).rule).

10Base210Base2

10Base-T10Base-TIt runs 10 Mbps and uses It runs 10 Mbps and uses CSMA/CD.CSMA/CD.It is a star-wired bus topology. It is a star-wired bus topology. It is still used today due to its It is still used today due to its reliability and ease of use. reliability and ease of use.

10Base-T10Base-T

100Base-T100Base-TIt uses CMSA/CD as a star-wired bus.It uses CMSA/CD as a star-wired bus.There are three subcategories of There are three subcategories of 100Base-T networks with different 100Base-T networks with different cable requirements. cable requirements. The most common is 100Base-TXThe most common is 100Base-TX (Category 5 or higher UTP).(Category 5 or higher UTP).

Switched EthernetSwitched EthernetA switch knows which segment A switch knows which segment belongs to which device.belongs to which device.

It uses a table stored in memory It uses a table stored in memory to send a packet. to send a packet.

It increases bandwidth by It increases bandwidth by decreasing traffic and collisions.decreasing traffic and collisions.

Switched EthernetSwitched Ethernet

Gigabit EthernetGigabit Ethernet 1000Base-T is a star topology 1000Base-T is a star topology that uses Category 5 or higher that uses Category 5 or higher cabling.cabling.

It increases speed by sending It increases speed by sending more bits and using 4 pairs of more bits and using 4 pairs of wires simultaneously. wires simultaneously.

WLANWLANWireless local area networkWireless local area networkIt is used when mobility is needed, It is used when mobility is needed, but it still must remain connected to but it still must remain connected to the network.the network.802.11b or Wi-Fi (11 Mbps)802.11b or Wi-Fi (11 Mbps)802.11a or Wi-Fi5 (108 Mbps)802.11a or Wi-Fi5 (108 Mbps)802.11g (54 Mbps) 802.11g (54 Mbps)

WLANWLANOnly wireless network interface cards and Only wireless network interface cards and access points are needed.access points are needed.

An access point acts as a link between An access point acts as a link between wireless and wired networks.wireless and wired networks.

802.11b uses Carrier Sense Multiple 802.11b uses Carrier Sense Multiple Access with Collision Avoidance Access with Collision Avoidance (CSMA/CA).(CSMA/CA).

WLANWLAN

Network DesignNetwork DesignBasic rules should be followed for a good Basic rules should be followed for a good network design.network design.

The switches in an Ethernet network must The switches in an Ethernet network must be configured in a hierarchy.be configured in a hierarchy.

Smaller network segments are better than Smaller network segments are better than larger network segments.larger network segments.

SummarySummaryIn the early 1980s, the Institute of Electrical and In the early 1980s, the Institute of Electrical and Electronic Engineers (IEEE) began work on developing Electronic Engineers (IEEE) began work on developing computer network architecture standards. Known as computer network architecture standards. Known as Project 802, this work estab-lished the foundation for Project 802, this work estab-lished the foundation for three network architecture standards that make up over three network architecture standards that make up over 95 percent of the LANs in use today. These three 95 percent of the LANs in use today. These three dominant standards are Ethernet (802.3), token ring dominant standards are Ethernet (802.3), token ring (802.5), and wireless (802.11).(802.5), and wireless (802.11).

IEEE Project 802.3 set specifications for a type of local IEEE Project 802.3 set specifications for a type of local area network known as Ethernet. Several versions of area network known as Ethernet. Several versions of Ethernet trans-mit at 10 Mbps, but these are rarely used Ethernet trans-mit at 10 Mbps, but these are rarely used today. 10Base5, also called Standard Ethernet, required today. 10Base5, also called Standard Ethernet, required the use of thick coaxial cable. Other versions of 10 Mbps the use of thick coaxial cable. Other versions of 10 Mbps Ethernet were designed to run over fiber optic cable in Ethernet were designed to run over fiber optic cable in specific settings.specific settings.

Summary (continued)Summary (continued)10Base2 is a version of Ethernet that used to be very 10Base2 is a version of Ethernet that used to be very popular and is still used today, although not as popular and is still used today, although not as extensively. 10Base2 is a bus topology that uses extensively. 10Base2 is a bus topology that uses contention (CSMA/CD) and requires thin coax cable as contention (CSMA/CD) and requires thin coax cable as the transmission media. 10Base-T also runs at 10 Mbps, the transmission media. 10Base-T also runs at 10 Mbps, uses CSMA/CD, and can support a total of 1,024 uses CSMA/CD, and can support a total of 1,024 devices on the network. 10Base-T is a star-wired bus devices on the network. 10Base-T is a star-wired bus topology, which means it functions like a bus (in that topology, which means it functions like a bus (in that each packet makes a stop at every device), but is wired each packet makes a stop at every device), but is wired like a star (with one central controlling device).like a star (with one central controlling device).

Summary (continued)Summary (continued)As faster network architectures were needed beyond 10 As faster network architectures were needed beyond 10 Mbps, the IEEE subcommittee began work on creating a Mbps, the IEEE subcommittee began work on creating a new Ethernet standard called 100Base-T (or Fast new Ethernet standard called 100Base-T (or Fast Ethernet). 100Base-T has many of the same basic Ethernet). 100Base-T has many of the same basic characteristics as 10Base-T. It uses CSMA/CD as its characteristics as 10Base-T. It uses CSMA/CD as its channel access method, the topology is a star-wired bus, channel access method, the topology is a star-wired bus, and it continues to use the same basic equipment (such and it continues to use the same basic equipment (such as hubs in distribution racks with patch panels). The only as hubs in distribution racks with patch panels). The only new items for 100Base-T networks were 100-Mbps NICs new items for 100Base-T networks were 100-Mbps NICs and 100-Mbps hubs. To increase the speed even more, and 100-Mbps hubs. To increase the speed even more, a switch (or a switching hub) is used. A switch knows a switch (or a switching hub) is used. A switch knows which segment goes to which network device. This which segment goes to which network device. This dramatically increases the band-width on the network dramatically increases the band-width on the network because it decreases the traffic and the number of because it decreases the traffic and the number of collisions. Ethernet networks that use switching hubs are collisions. Ethernet networks that use switching hubs are often called Switched Ethernet.often called Switched Ethernet.

Summary (continued)Summary (continued)Gigabit Ethernet (or 1000Base-T) is the standard that Gigabit Ethernet (or 1000Base-T) is the standard that most closely resembles 100Base-TX. 1000Base-T is a most closely resembles 100Base-TX. 1000Base-T is a star topology that uses Category 5 or higher cabling. star topology that uses Category 5 or higher cabling. 1000Base-T achieves its higher speed by increasing the 1000Base-T achieves its higher speed by increasing the number of bits sent and sending data in over all four number of bits sent and sending data in over all four pairs of wires simultaneously. 10G Ethernet transmits at pairs of wires simultaneously. 10G Ethernet transmits at 10 billion bits per second.10 billion bits per second.

Summary (continued)Summary (continued)IEEE Project 802.5 set specifications for a type of local IEEE Project 802.5 set specifications for a type of local area network known as token ring. Token ring runs at 16 area network known as token ring. Token ring runs at 16 Mbps and uses twisted pair cable in a hybrid star ring Mbps and uses twisted pair cable in a hybrid star ring topology. The packets in a star ring do not go directly to topology. The packets in a star ring do not go directly to the next device on the ring; instead, they go to a central the next device on the ring; instead, they go to a central hub, which then sends the packet to the next device on hub, which then sends the packet to the next device on the ring. At the center of a token ring network is a hub, the ring. At the center of a token ring network is a hub, called the Multistation Access Unit (MAU). Token ring called the Multistation Access Unit (MAU). Token ring also has the ability to diagnose and avoid network also has the ability to diagnose and avoid network problems.problems.

Summary (continued)Summary (continued)Wireless local area networks (WLANs) are found Wireless local area networks (WLANs) are found anywhere a user needs mobility but still must remain anywhere a user needs mobility but still must remain connected to a net-work. The list of components connected to a net-work. The list of components necessary for a WLAN is short. Only wireless network necessary for a WLAN is short. Only wireless network interface cards and access points are needed for interface cards and access points are needed for communication to take place. A wireless NIC per-forms communication to take place. A wireless NIC per-forms the same functions as a wired NIC except an antenna is the same functions as a wired NIC except an antenna is used to send and receive radio frequency signals. An used to send and receive radio frequency signals. An access point (AP) is a device that contains a radio access point (AP) is a device that contains a radio transceiver (to send and receive signals) along with an transceiver (to send and receive signals) along with an RJ-45 wired network inter-face, which allows it to RJ-45 wired network inter-face, which allows it to connect by cable to a standard wired network.connect by cable to a standard wired network.

Networking BASICSNetworking BASICS

Protocols and Network Protocols and Network SoftwareSoftware

ObjectivesObjectivesExplain the OSI reference model.Explain the OSI reference model.

Define protocol.Define protocol.

List and describe the functions of List and describe the functions of TCP/IP.TCP/IP.

Explain the functions of client and Explain the functions of client and server network software.server network software.

OSI Reference ModelOSI Reference Model It was created by the International It was created by the International Standards Organization (ISO).Standards Organization (ISO).

It breaks network functions into seven It breaks network functions into seven layers.layers.

It illustrates how each layer provides It illustrates how each layer provides specific services and shares with the specific services and shares with the layers above and below.layers above and below.

OSI Reference ModelOSI Reference Model The “flow” between layers goes The “flow” between layers goes downdown when data is sent and when data is sent and upup when data is received.when data is received.The function that each layer The function that each layer performs is to add or remove performs is to add or remove network information on a packet. network information on a packet.

OSI Reference ModelOSI Reference Model

ProtocolProtocolssProtocols are rules for communication. Protocols are rules for communication.

A combination of protocols is called a A combination of protocols is called a protocol stack or protocol suite. protocol stack or protocol suite.

A connectionless protocol assumes that A connectionless protocol assumes that packets will arrive.packets will arrive.

A connection-oriented protocol establishes A connection-oriented protocol establishes a link between devices.a link between devices.

TCP/IPTCP/IP Transmission Control Transmission Control Protocol/Internet Protocol (TCP/IP)Protocol/Internet Protocol (TCP/IP)It is the most common protocol suite It is the most common protocol suite used today for LANs as well as the used today for LANs as well as the Internet. Internet. It is composed of several different It is composed of several different protocols.protocols.

TCP/IPTCP/IP

Internet Protocol (IP)Internet Protocol (IP) The hosts on a TCP/IP network use a The hosts on a TCP/IP network use a logical address.logical address.

This logical address, called the IP This logical address, called the IP address, is assigned to each host. address, is assigned to each host.

IP is responsible for the addressing of IP is responsible for the addressing of packets. packets.

IP AddressingIP Addressing An IP address is four bytes (octets). An IP address is four bytes (octets). Each contains eight bits (total of 32 Each contains eight bits (total of 32 bits in length). bits in length). Each octet is a number from 1 to 254.Each octet is a number from 1 to 254.IP addresses are usually given as IP addresses are usually given as dotted decimal notation.dotted decimal notation.

IP AddressingIP Addressing

Subnet MaskSubnet Mask A subnet maskA subnet mask is used to separate a is used to separate a network number from the host network number from the host number in an IP address. number in an IP address. 1 represents a network and 0 1 represents a network and 0 represents a host. represents a host. Subnet masks are also used to Subnet masks are also used to subdivide networks. subdivide networks.

Transmission Control Protocol Transmission Control Protocol

(TCP)(TCP) TCP is responsible for the reliable TCP is responsible for the reliable transmission of data from one host to transmission of data from one host to another.another.It is based on port numbers. It is based on port numbers. The combination of an IP address The combination of an IP address and a port number is called a socket. and a port number is called a socket.

IPv6IPv6 The current version of the IP protocol is The current version of the IP protocol is IPv4. IPv4. The next generation of the IP protocol is The next generation of the IP protocol is called IPv6. called IPv6. 340 trillion, trillion, trillion addresses340 trillion, trillion, trillion addressesIt uses a fixed packet header size of 24 It uses a fixed packet header size of 24 bytes so that information always appears bytes so that information always appears in the same place. in the same place.

Network SoftwareNetwork Software Software that runs on the Software that runs on the client client

Software that runs on the Software that runs on the server server

Client Software Client Software Network Driver InterfacesNetwork Driver Interfaces - “Middleman” - “Middleman” between NIC and client’s operating system between NIC and client’s operating system software.software.

RedirectorRedirector - Sends request to network. - Sends request to network.

DesignatorDesignator - Keeps track of which drive - Keeps track of which drive letter is associated with which network letter is associated with which network device.device.

Server Software Server Software Network operating systemNetwork operating system - - Manages and coordinates users and Manages and coordinates users and requests across the network.requests across the network.

Directory serviceDirectory service - Database stored - Database stored on the network containing information on the network containing information about users and privileges to about users and privileges to resources.resources.

SummarySummaryThe International Standards Organization (ISO) released The International Standards Organization (ISO) released a set of specifications that was intended to describe how a set of specifications that was intended to describe how dissimilar computers could be connected together on a dissimilar computers could be connected together on a network. Called the Open Systems Interconnections network. Called the Open Systems Interconnections (OSI) reference model, it illustrates how a network (OSI) reference model, it illustrates how a network device prepares data for delivery over the network to device prepares data for delivery over the network to another device and how data is handled when it is another device and how data is handled when it is received. The key to the OSI reference model is layers. received. The key to the OSI reference model is layers. The model breaks networking steps down into a series of The model breaks networking steps down into a series of seven dif-ferent layers. Each layer cooperates with the seven dif-ferent layers. Each layer cooperates with the layer immediately above and below it by sending and layer immediately above and below it by sending and receiving information.receiving information.

Summary (continued)Summary (continued)The rules for communication between network devices The rules for communication between network devices are known as protocols. These protocols are essential are known as protocols. These protocols are essential for proper communication to take place between the OSI for proper communication to take place between the OSI reference models on the network devices. Instead of reference models on the network devices. Instead of having just one single proto-col, computer networks having just one single proto-col, computer networks typically employ several different proto-cols that function typically employ several different proto-cols that function together. This combination of protocols is known as a together. This combination of protocols is known as a protocol stack or a protocol suite. Protocols use one of protocol stack or a protocol suite. Protocols use one of two different methods for delivering data through a two different methods for delivering data through a network: connectionless protocols, which place the network: connectionless protocols, which place the packets on the net-work and then assume that they will packets on the net-work and then assume that they will arrive at the destination, and connection-oriented arrive at the destination, and connection-oriented protocols, which establish a connection between the two protocols, which establish a connection between the two devices before sending any packets. As each packet is devices before sending any packets. As each packet is received, an acknowledgment is sent back to the sender.received, an acknowledgment is sent back to the sender.

Summary (continued)Summary (continued)The most common protocol suite used today for LANs as The most common protocol suite used today for LANs as well as the Internet is Transmission Control well as the Internet is Transmission Control Protocol/Internet Protocol (TCP/IP). Because it is a suite, Protocol/Internet Protocol (TCP/IP). Because it is a suite, TCP/IP is composed of several different protocols that all TCP/IP is composed of several different protocols that all function together. Although the TCP/IP suite is function together. Although the TCP/IP suite is composed of several different protocols, the two major composed of several different protocols, the two major protocols are those that make up its name, TCP and IP. protocols are those that make up its name, TCP and IP. The IP is responsible for addressing the packets and The IP is responsible for addressing the packets and sending them on the correct route to the destination. sending them on the correct route to the destination. Each device on a TCP/IP computer network must have a Each device on a TCP/IP computer network must have a unique number. Com-puters on a TCP/IP network use a unique number. Com-puters on a TCP/IP network use a logical address instead. This logical address, called an logical address instead. This logical address, called an IP address, is assigned to each host computer.IP address, is assigned to each host computer.

Summary (continued)Summary (continued)Server software plays a critical role on a computer Server software plays a critical role on a computer network. A network server uses network operating network. A network server uses network operating system (NOS) software. NOS software manages and system (NOS) software. NOS software manages and coordinates all users and their requests across the coordinates all users and their requests across the network. A directory service is a database stored on the network. A directory service is a database stored on the network. It contains information about users and network network. It contains information about users and network devices. A directory service also keeps track of the devices. A directory service also keeps track of the resources on the network and a user’s privileges to resources on the network and a user’s privileges to those resources.those resources.