15-1 networking. 15-2 section objectives after completing this section you will be able to: ...

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Networking

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Section Objectives

After completing this section you will be able to: Differentiate between peer-to-peer and server-based networks Identify commonly used network topologies Compare and contrast types of network cabling Explain the differences between various network access methods Explain how Ethernet works Identify OSI model layers and the network devices that work at each layer Articulate commonly used network protocols Define the purpose and identification of a MAC address and an IP address Apply IP addressing concepts Define the purpose of DHCP, WINS, and DNS Configure an NIC for network connectivity

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Networking Overview

A network is two or more devices capable of communicating and sharing resources between them.

Types of networks:– PAN (Personal Area Network) – Personal devices such as PDAs can

communicate in close proximity through a wired or wireless network.

– LAN (Local Area Network) – A group of devices sharing resources in a single area such as a room or a building.

– MAN (Metropolitan Area Network) – Connectivity of sites within a city.

– WAN (Wide Area Network) – Two or more LANs communicating, often across large distances. The most famous WAN is the Internet.

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Types of Local Area Networks

Types of LANs:– Server-Based Network (client-server network)– A type of

LAN wherein users login to a controlling computer, called a server and is more secure. These networks normally consist of 10 or more computers.

– Peer-to-Peer Network – A type of LAN wherein each computer user acts as a server. Each computer stores password and sharing information for its own resources. Usually has fewer than 10 computers.

NOS (Network Operating System) – Special operating system on a server containing utilities for managing users, resources, and security.

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Types of Local Area NetworksServer-Based network

Network – Figure 15.1

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Types of Local Area Networks


Peer-to Peer network

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Network Topologies

Physical network topology – How the network is wired.

Ethernet – The most common type of network.

Hub – A device that allows multiple device connections. Hubs are not as intelligent as switches.

Switch – A switch looks at each data frame as it comes through each port.

Star Topology – Most common network topology. Each device connects to a central hub or switch.

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Network Topologies


Hub (switch)

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Network Topologies


Star topology

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Network Topologies

Network – Table 15.2

Network topologies

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Network Media Overview

Cable or air are used as mediums for transporting

network data.

The most common types are twisted-pair and fiber-

optic, although coax is still used in some old networks.

Wireless networks use the air to transmit data over

radio frequencies.

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Copper Media

Twisted-Pair Cable – Network cable of eight copper wires twisted into four

pairs to prevent crosstalk.

– UTP (Unshielded Twisted-Pair) – Most common network cable that

comes in different categories for different uses. Categories 5e and 6. It is

unshielded and more susceptible to interference.

– STP (Shielded Twisted-Pair) – Same as UTP cable, but with extra foil

to prevent outside noise from interfering with data on the cable.

Crosstalk – Where signals from one wire interfere with the signal on an

adjacent wire.

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Network Cabling


UTP cable

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Copper Media

Plenum cable is treated with Teflon or fire retardant materials

to reduce the risk of fire. It produces less smoke and is less

toxic when burning.

PVC (polyvinyl chloride) – Cable with a plastic cable insulation

or jacket. PVC is an alternative to Plenum cable.

Coaxial Cable (coax) – Type of copper network cabling used in

older Ethernet networks as well as mainframe and

minicomputer connections. Has a single, center wire conductor

with an outer braided shield.

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Network Cabling


UTP wiring standards

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Network Cabling


RJ-45 pin 1 assignments

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Network Cabling


Coax cable with connector

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Fiber Media

Fiber-Optic Cable – An expensive network cabling made of plastic or glass fibers that carry data in the form of light pulses. Most often used to connect network devices such as switches together into a network backbone or for connecting networks together in a WAN. More secure and not affected by crosstalk or other interference like copper cable.– Single-Mode – A type of fiber-optic cabling that sends one light beam

down the cable. Used for longer distance applications.

– Multi-Mode – A type of fiber-optic cabling that allows multiple light signals to be sent along the same cable. Used for shorter distances.

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Network Cabling


Fiber-optic cable

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Access Methods

There are standard rules by which computers on a network must adhere to in order to communicate. These rules are known as a common access method.

CSMA/CD (Carrier Sense Multiple Access/Collision Detect) – A common access method used by Ethernet.

Token Passing – The common access method used by fiber and Token Ring networks.

Token – Small data packet passed from one networked device to another in a ring topology.

CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) – A common access method used in wireless and Apple networks.

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Ethernet Issues and Concepts

Two types of transmissions used in Ethernet networks: Half Duplex – Allows either the sending or the

receiving device to send data, one device at a time. Data can travel both ways on a cable, but not at the same time.

Full Duplex – Allows the sending and receiving device to send data simultaneously. Data can travel both ways on a cable at the same time.

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Network Standards


IEEE 802 standards

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OSI Model

OSI Model (Open Systems Interconnect) – A standard for information transfer across a network that was developed by the International Standards Organization. The model has 7 layers.– Physical Layer – Layer 1 of the OSI model that defines how

bits are sent and received across the network without regard to their structure.

– Data Link Layer – Layer 2 of the OSI model that accurately transfers bits across the network by encapsulating (grouping) them into frames.

– Network Layer – Layer 3 of the OSI model that coordinates data movement between two devices on separate networks.

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OSI Model

– Transport Layer – Layer 4 of the OSI model that determines details on how the data is sent, supervises the validity of the transmission, and defines protocol for structuring messages.

– Session Layer – Layer 5 of the OSI model that manages communication and administrative functions between two network devices.

– Presentation Layer – Layer 6 of the OSI model that defines how data is formatted, encoded, converted, and presented from the sender to the receiver, even though different computer language is used.

– Application Layer – Layer 7 of the OSI model that defines how applications and the computer interact with a network, and negotiates services such as authentication, error recovery, and quality of service.

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OSI Model

ISP (Internet Service Provider) – A vendor that provides connection to the Internet.

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OSI Model


OSI model layers

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OSI Model


OSI peer communication

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OSI Model


OSI model

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Networking Protocols

Network Protocol – Data communication language.– TCP/IP (Transport Control Protocol / Internet Protocol) –

The most common network protocol used by most companies and home users as a standard protocol. Used to access the Internet.

– IPX/SPX (Internetwork Packet Exchange/Sequenced Packet Exchange) – Original protocol used for connecting to Novell networks. Now TCP/IP is the standard protocol used.

– NetBEUI (NetBIOS Enhanced User Interface) – Is a non-routable protocol used in simple networks.

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Network Addressing

Network devices have to be able to identify each other in order to communicate across a network. They do this through various network addressing schemes.

MAC Address – A 48-bit unique number that is burned on the ROM chip of the NIC.

IP Address – It is a 32-bit binary number with groups of eight bits separated by a dot.

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IP Addressing

Network Number – Portion of an IP address that represents which network the computer is on.

Host Number – Portion of an IP address that represents the specific network device.

Broadcast Address – IP address used to communicate with all devices on a particular network.

Subnet Mask – A number the computer uses to determine which part of an IP address represents the network and which portion represents the host.

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Network Addressing


IP Addressing (network and host portions)

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IP Addressing


IP addressing (two network example)

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IP Addressing


IP addressing information

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DUN (Dial-Up-Networking)

DUN (Dial-Up Networking) – A remote computer that dials into the Internet or a corporation using a modem.

PPP (Point-to-Point Protocol) – A connection-oriented that encapsulates data for transmission over various connection types.

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Dial-up NetworkingNetwork connections


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Internet Software

Once a connection is established to a remote network there are several program types that are useful for accessing data.

Browser – A program that views web pages across the Internet. The common browsers include Internet Explorer, Netscape Navigator, and Mozilla FireFox2.

Plug-in – An application, such as Macromedia Flash, designed to work with the browser.

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Wireless Networks Overview

Wireless Networks – Transmit data over air using either infrared or radio frequencies. Wireless networks operate at layers 1 and 2 of the OSI model.

Bluetooth – Wireless technology for PANs. Piconet – A small network.

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Wireless Networks Types

There are two main types of wireless networks:– Ad hoc – Also known as peer-to-peer or IBSS (Independent

Basic Service Set) – An ad hoc wireless network is when at least two devices such as two computers have wireless NICs.

– Infrastructure – Wireless network that connects multiple wireless network devices through an Access Point.

There are three major types of wireless NICs: PC Card, USB, and PCI.

Access Point – Is similar to a network hub and connects wireless network devices.

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Wireless Networks Types

BSS (Basic Service Set) – Configuration when multiple devices connect to an access point.

ESS (Extended Service Set) – The network design when multiple access points connect to the same main network.

SSID (Service Set Identifier) – A set of 32 alpha numeric characters used to differentiate between wireless networks.

The channel ID (frequency) between the Access Point and the adapter must match for communication to occur.

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Wireless Networks Types802.11b/g frequency channels


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Wireless Network Standards

Modulation – When data is added to a carrier signal.

IEEE 802.11 standards


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Wired or Wireless NIC Installation

When installing a NIC, you must configure the following prior to connecting to the network:Determine that an appropriate port, slot, or

integrated wireless NIC is available.Install the appropriate NIC drivers.Assign the computer an appropriate name and a

workgroup or domain name.Configure the network protocol and client.

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Configuring Networking

Some key terms to understand when configuring computers for networking are:

DHCP (Dynamic Host Configuration Protocol) – A method to automatically assign IP addresses to network devices from a pool of IP addresses. A computer requests an address from another device running DHCP, usually a server, receives it, and joins the network.

Default Gateway – The IP address of the Layer 3 device, such as a router, that is directly connected to its immediate network and acts as a doorway or director to other remote networks.

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DNS (Domain Name System) Server – Application on a network server that translates Internet names into IP addresses.

URL (Universal Resource Locator) – A method of accessing Internet resources by using a simple, easily remembered name assigned to an IP address.

WINS (Windows Internet Naming Service) Server – Keeps track of IP addresses assigned to a specific computer name. A user can type in a computer name to connect and the server will translate it to the computer’s IP address.

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Wired or Wireless NIC Installation

Before installing a wireless NIC, be sure to confirm the basic configuration settings for the wireless network.

Install the NIC by following the manufacturer’s instructions.

Configure the basic wireless network settings to begin communication on the network.

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Default gateway

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Network Troubleshooting

Some commands that are useful to a technician when diagnosing network connection issues:

Ping – A command used to test TCP/IP communications and determine if a network path is available. You can type ping and either a domain name or IP address and connectivity to that device will be tested.

IPCONFIG – A command used with Windows XP and 2000 to see and modify the current IP settings.

NSLOOKUP – An NT, 2000, XP and 2003 Server troubleshooting tool that displays network domain names and their associated IP addresses.

Tracert – A command that displays the path a data packet takes through a network, thus allowing one to see where a fault occurs in larger networks.

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Sample network configuration

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IPCONFIG and IPCONFIG /ALL

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Network Terminology

Networking Terms and Acronyms To be Familiar With:Backbone Bandwidth BasebandBroadband E-mail Fast EthernetFDDI Frame FTPHTML HTTP InfraredPacket POP SNMPTCP Telnet UDP

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Sharing

Network share – A folder that has been shared and can be accessed from a remote computer.

UNC (Universal Naming Convention) – A standard way of naming computers and shared resources on a network. Used at the command prompt to obtain network shares.

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Email

SMTP (Simple Mail Transport Protocol) – is a protocol used for sending and receiving email. Settings for configuring email can be obtained from the network administrator or the ISP being used to connect to the Internet.

POP3 (Post Office Protocol) and IMAP (Internet Mail Access Protocol) are methods used to receive email to a person’s account.

MAPI (Messaging Application Programming Interface) – Microsoft’s proprietary alternative email protocol.

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15-1 networking. 15-2 section objectives after completing this section you will be able to: ...

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