networking pp t 1705

7/28/2019 Networking Pp t 1705

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Introduction to Networking

Definitions and Terms


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Objectives

After completing these slides you will:

Be able to differentiate between peer-to-peer and server-based networks.

Be able to identify a network topology.

Understand the different types of network cabling.

Be able to explain the differences between various network access methods.

Understand Ethernet issues.

Identify logical layers of the internet.

Be able to explain when a specific network protocol is used.

Understand the difference between a MAC address and an IP address.


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Networking Overview

A network is two or more devices capable of communicating and sharing

resources between them.

Two types of networks are LAN and WAN:

LAN (Local Area Network) A group of devices sharing resources in

a single area such as a room or a building.

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

Two types of LANs are Server-Based and Peer-to-Peer Network:

Server-Based Network A basic type of LAN wherein users login toa controlling computer, called a server and is more secure. The server

contains information about who can connect to the network and to

what shared resources. It also provides some of these resources.

These networks normally consist of 10 or more computers.

Peer-to-Peer Network One of two basic types of LANs 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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Server-Based Network

Network Figure # 1


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Network Figure # 2

Peer-to Peer Network


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Network Topologies

Network Topology Maps of how the physical or logical paths of network

devices connect. The three major topologies are star, ring, and bus.

Star Topology Most common Ethernet network topology where each device

connects to a central hub or switch.

Hub A device used with the Universal Serial Bus or in a star network topology

that allows multiple device connections.

Switch In star networks, a Layer 2 central controlling device. A switch looks ateach data frame as it comes through each port.

Ring Topology Network that is physically wired like a star network but,

logically in a ring; passes control from one device to the next in a continuous

fashion using a special data packet called a token. Used in Token Ring networks.

Bus Topology Network wherein all devices connect to a single cable. If the

cable fails, the network is down.

Mesh Topology Network where all devices connect to each other by cabling to

provide link redundancy for maximum fault tolerance. Most likely in WANs.


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Network Topologies

Network Figure # 3

Hub/Switch


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Network Topologies

Network Figure # 4

Star Topology


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Network Topologies

Logical Ring Topology

Network Figure # 5


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Network Topologies

Network Figure # 6

Bus Topology


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Network Topologies

Network Table # 1

Network Topologies

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Network Cabling

Cable is normally used as a medium for transporting network data. The most

common types are twisted-pairand fiber-optic, although coax is still used in some

old networks.

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 3 (voice-grade), 4, and 5(data). 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.

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.

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Network Cabling

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 beamdown 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.

Coaxial Cable 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

Network Figure # 7

UTP Cable

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Network Cabling

Network Figure # 11

Fiber-Optic Cable

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Network Cabling

Network Figure # 12

Coax Cable with Connector

A M th d


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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.

CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) A

common access method used in wireless and Apple networks.

Token Small data packet passed from one networked device to

another in a ring topology.

Ethernet IssuesandConcepts


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Ethernet Issues and Concepts

Two types of transmissionsused in Ethernet networks:

Half Duplex A serial device setting that allows either the sending or thereceiving 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 A serial device setting that allows the sending and

receiving device to send data simultaneously. Data can travel both ways

on a cable at the same time.

Layersof theInternet


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Layers of the Internet

One logical view of the Internet has five layers

Physical Layer Layer 1 this model defines how bits are sent andreceived across the network between two pieces of hardware.

Data Link Layer in layer 2 bits are transferred across the network

by encapsulating (grouping) them into frames.

Network Layer in layer 3 the segments are sent between the

sender and receiver.

Transport Layer in layer 4 breaks a message into segments and

passes to the Network Layer.

Application Layer in layer 5 we have network related applications

like telnet, ftp, etc.

Layersof theInternet


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Layers of the Internet

In the Physical layer actual bits are sent either as electrical signals on

wires, or electromagnetic radiation through fiber-optic cables or

transmitted.

In the Data Link layer the information being transmitted is a frame that

has the actual info (datagram), header and trailer. The frame headers

use MAC addresses to identify source and destination.

The Data Link layer is implemented in the network adapter (NIC) and is a

combination of hardware, software, and firmware.

MAC (Media Access Control) is a 48-bit address burned in NIC ROM.

NetworkingProtocols


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Networking Protocols

Network Protocol Specifications that define the network data

communication procedures to follow when sending and receiving data.

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; commonly found on peer-to-peer

networks.

Network Addressing


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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 One of two types of addresses assigned to network

adapters, used when two devices on same network communicate.

IP Address A type of network adapter address used when multiple

networks are linked. It is a 32-bit binary number with groups of eight bits

separated by a dot.

Network Number Portion of an IP address that represents which

network the computer is on.

Network Addressing


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Network Addressing

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.

Network Addressing


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Network Addressing

Network Figure # 15

IP Addressing (Network Number and Host Number)

Network Addressing


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Network Addressing

Network Figure # 16

IP Addressing (Two Network Example)

Network Addressing


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Network Addressing

Network Table #5

IP Address Information

ConfiguringNetworking


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Configuring Networking

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

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.

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.

APIPA (Automatic Private IP Addressing) Assigns an IP address and mask to

the computer when a DHCP server is not available.

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 (also known as Fully Qualified Domain

Names or hostnames) 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. An example of a URL is: www.scottjonespub.com, which ismuch easier to remember than the IP address : 167.160.239.173.

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

computers IP address.



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Network Figure #17

Default Gateway

Network Troubleshooting


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IPCONFIG A command used with Windows 98, NT, and 2000 to see

and modify the current IP settings.

NSLOOKUP An NT Server and 2000 Server troubleshooting tool that

displays network domain names and their associated IP addresses.

Tracert A network troubleshooting 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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Network Figure #18

Sample Network Configuration



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Network Figure #19

WINIPCFG



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Network Figure #20

IPCONFIG

Dial-upNetworking


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Dial up Networking

There are several ways in which computers can connect to remote

networks:

DUN (Dial-Up Networking) A remote computer that dials into the

Internet or a corporation using a modem.

VPN (Virtual Private Networking) A remote computer connecting to a

remote network by tunneling over an intermediate network, such as the

Internet or a LAN.

PPP (Point-to-Point Protocol) A connection-oriented Layer 2 protocol

that encapsulates data for transmission over remote networks. Very

common for home users dialing in to the Internet.

Dial-upNetworking


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Dial up Networking

Dial-Up Networking and VPN

Network Figure #21

Dial-up Networking


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a up e o g

Network Connections

Network - Table #7

Internet Software


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Once a connection is establishedto 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 two

most common are Internet Explorer and Netscape Navigator.

Proxy Server Acts as an agent between an application and a real

server for security purposes.

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.

Internet Security


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y

There are three major points to remember:

Keep service patches updated on a regular basis.

The latest anti-virus software should be installed and constantly

updated.

If the computer connects to the internet, it should be connected

behind a firewall.

Cookie A special program written to collect information and store it on

the hard drive. This will contain your preferences when you visit a

website.

Firewall Software or hardware that protects one or more computers

from outside attacks.

Network Terminology


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gy

Networking Terms and Acronyms To be Familiar With:

Backbone Bandwidth Baseband

Broadband E-mail Fast Ethernet

FDDI Frame FTP

HTML HTTP Infrared

Packet POP SNMP

TCP Telnet UDP

Wireless Networks Overview


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Wireless Networks Transmit data over air using either infrared or radio

frequencies. Wireless networks operate at layers 1 and 2 of the OSI

model.

Wireless Networks Types


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yp

There are two main types of wireless networks:

Ad hoc also known as peer-to-peer or IBSS (Independent BasicService 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.

Access Point is similar to a network hub and connects wireless network

devices.

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



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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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802.11b Frequency Channels

Network Table #12

Wireless Network Security Overview


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Wireless networks by their nature are insecure.

All transmissions over air occur in clear text making them easy tocompromise.

Authentication and WEP


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Authentication is the process of determining that a network device or

person has permission to enter the wireless network through the access

point.

Open Authentication Allows a wireless network device to send a frame

to the access point with the senders identity (MAC address). It is used

when no authentication is required.

Shared Key Authentication Requires the use of a shared key to

communicate.

WEP (Wireless Equivalent Privacy) Encrypts data when shared key

authentication is used.

Encryption the process of converting data into an unreadable format.

Default Settings


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All wireless networks have default passwords and SSIDs. They should

be changed immediately to prevent hackers from gaining access.

SSID Broadcasting The access point periodically sends out a beacon

frame that includes the SSID.

Default Access Point Passwords

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