Chapter 9: Networking

NetworkingChapter 9

Overview

• In this chapter, you will learn to– Explain network technologies– Explain network operating systems– Install and configure wired networks– Install and configure wireless networks– Troubleshoot networks

Networking Technologies

Sneakernet

• To share files used to require making copies to a floppy and running them over to someone else…sneakernet

• A way needed to be devised for computers to share information and resources

• A network is two or more computers connected together to share resources

The Big Questions

• How will each computer be identified?– If two or more computers want to talk at the same

time, how do you ensure all conversations are understood?

• What kind of wire should be used to connect the computers together?– How many wires in the cable? How thick? How

long? What type of connectors?

• How can access to data and peripherals be controlled?

• And the list goes on and on…

A Few Basics

• A client machine requests information or services

• Uses a network interface card (NIC) to define the client on the network and to physically make a connection

• A medium to connect the devices is needed– Cable or wireless

• The operating system needs to understand how to network

• A server provides information or services to the client

Packets, Frames, and NICs

• Data is broken up into small pieces and moved about the network in chunks called packets or frames

• Every network interface card (NIC) has a built-in identifier called a Media Access Control (MAC) address– No two NICs have the same MAC address anywhere

in the world– Burned into a chip on the card

MAC Address

• Start Programs Accesories System Tools System Information

Packet Fields

• Packets contain the following fields– MAC address of the network card that it is being

sent to– MAC address of the network card that sent the

packet– Data– Data check or cyclic

redundancy check (CRC) used to verify the data’s integrity

Protocols

• Protocols are sets of rules– May be used to define packet types, cabling and

connectors, addresses, and much more

• A hardware protocol defines how to get data from one computer to another– Ethernet is the dominant standard for today’s

networks• Coaxial• Unshielded twisted pair• Fiber optic

– Token Ring was developed by IBM but is loosing popularity

Coaxial Ethernet

• Early Ethernet networks used coaxial cable (or just coax)– Composed of a center cable surrounded by

insulation, a shield of braided cable, and an outside protective cover

– A different type of coaxial cable is used by your VCR and TV

Thick Ethernet – 10Base5

• Thick Ethernet cable (Thicknet) is used in the 10Base5 Ethernet

specification– Called RG-8 (Radio Grade)

cable– 10Base5

• 10 means that data is transferred at 10 Mbps• Base refers to baseband signaling• 5 means the maximum length of the cable is 500 meters

– Uses a bus topology where all devices attach to a single cable

• Computers are connected one to another• Every computer receives every packet of information

CSMA/CD

• Carrier Sense Multiple Access/Collision Detection (CSMA/CD) is a method used by computers to share the same cable– If two computers talk (try to send data) at the same

time, a collision results that corrupts the data

CSMA/CD

• To prevent collisions when there is multiple access to a cable, computers first do a carrier sense (listen to the cable for traffic) before trying to send data

CSMA/CD

• Even though the computers listen before sending data, it is possible that two computers listened at about the same time, heard nothing, and then sent data – resulting in a collision

• Computer NICs have collision detection circuitry that alerts them to a collision

Reflection and Termination

• Signals traveling along a wire will bounce back when they get to the end – called reflection

• As a result a terminator is installed on the ends of the cable to absorb the signal to prevent it from reflecting back – which would corrupt the signal

Connections

• Thicknet cable is marked every 2.5 meters– Devices are connected only at these marks by

using a vampire connector that pierces the cable to make a connection

– It is also a transceiver that transmits and receives data, sometimes called an access unit interface (AUI) that connects to a Digital, Intel, Xerox (DIX) connector

• Thicknet uses a bus topology– If there’s a break in the cable, the whole network

goes down

Thicknet Connections

Thin Ethernet – 10Base2

• Thin Ethernet is also known as Thinnet– Uses RG-58 coax cable– Limited to 30 devices per

segment– Cable length limited to 185 meters– Thinner and cheaper than Thicknet– Transceiver is built into the network card– Uses twist-on BNC connectors– Uses terminators

UTP Ethernet – 10BaseT

• Modern networks use UTP Ethernet– Modern networks do not use Thicknet or Thinnet– 10BaseT runs at 10 Mbps– 100BaseT runs at 100 Mbps– 1000BaseT (Gigabit) runs at 1000 Mbps– Use a star bus topology– Uses unshielded twisted pair (UTP) cabling

Star Bus Topology

• Most common topology used is a star bus– In a star topology all devices are connected to a

central device called a hub– Multiple hubs are connected together in a bus

topology– Together they form a star bus topology– Hubs have been replaced by switches that

conserve bandwidth

Unshielded Twisted Pair

• UTP is the predominant type of cabling used today– Pairs of wires are twisted together in an

unshielded cable– UTP cables come in categories (CATs) that define

the maximum speed at which data can be transferred (called bandwidth)

• CAT5, CAT5e, and CAT6 are most common today

Implementing 10*BaseT

• Requires at least two pairs of wires – one for receiving and one for sending

• Cables use special RJ-45 connectors• The Telecommunications Industry

Assciation/ Electronics Industries Alliance (TIA/EIA) has two standards for connecting the RJ-45 connectors– TIA/EIA 568A and TIA/EIA 568B– Use either – just be consistent– Wires are color-coded

Combo Cards

• All Ethernet networks share the same language

• Many NICs will run at either 10 or 100 Mbps

• Some NICs have both BNC and RJ-45 ports

Hubs and Switches

• Each PC is connected to a hub or switch in a 10*BaseT network– To add a device, just run

another cable to the hub or switch from the device

– The maximum separation between the device and the hub or switch is 100 meters

– Hubs act as a repeater that regenerates the signal before it sends it back out other ports

– Hubs come in 4, 8, 16, or 24 ports

Duplex and Half-Duplex

• Modern NICs can both send and receive data at the same time – called full duplex

• Older NICs could send and receive data but not at the same time – called half duplex

• NICs and switches use autosensing to decide how to operate

Fiber Optic Ethernet

• Fiber optic cable uses light instead of electricity– Immune to electrical interference– Signals can travel up to 2,000 meters– Most Ethernet uses 62.5/125 multimode cable– Uses two cables– Uses SC (square-shaped) or ST (round) connectors– Common standards are 10BaseFL and

100BaseFX– Usually reserved for the backbone due

to its expense

Token Ring

• Developed by IBM• Uses a star ring topology

– Incompatible with Ethernet– Data travels in a ring

• Uses token passing– A free token circulates the ring– A device may send data only when

it has the token

Implementing Token Ring

• Legacy Token Ring ran at 4 Mbps or 16 Mbps using IBM Type 1 cable– Two-pair, shielded twisted

pair (STP) cable– Today’s Token Ring

networks may use UTP or STP– STP comes in various types– Token Ring cables use an IBM-

type Data Connector (IDC) or Universal Data Connector (UDC) designed to plug into each other

– Uses a special hub called a multistation access unit (MSAU or MAU)

Parallel/Serial Connections

• All versions of Windows have software that allows two (and only two) PCs to connect together via their parallel or serial ports– Use a crossover IEEE 1284 cable for parallel ports– Use an RS-232 cable for serial ports

Network Operating System

Client/Server

• In a client/server environment one machine is dedicated as a resource to be shared over the network– Uses a special Network Operating System (NOS)

• Optimized for sharing files and printers or other resources

• Protects access to the data or resources using security features

– Called the server– All other machines are clients or workstations– Novell NetWare is an enterprise level NOS

Peer-to-Peer

• In a peer-to-peer network all machines on the network may act as a client or server

• Peer-to-peer network operating systems include– Windows 98/Me– Windows 2000/XP– Limited to 10 users accessing a file at one time– Useful for small networks only– Lacks security– Users are part of workgroups

Peer-to-Peer

Domain-Based

• In a peer-to-peer network you must log in to each server you wish to access

• In a domain-based network you log into the network just once to access resources throughout the network– Servers on the network may play one or several

roles• Domain Controller (holds the security database)• File server• Print server• Fax server• Remote Access Services (RAS) server• Application server• Web server

Domain Controllers

• Domain Controllers keep the security database of users and passwords– Directory services are used to store user names

and passwords• In Windows 2000 and 2003 server, it is called Active

Directory• In Novell NetWare it is called NetWare Directory

Services (NDS)

Administrative Tools

Administrative Tools in Windows XP Professional

Administrative Tools in Windows 2000 Server

Administrator Account

• The administrator account is a special user account that has complete and absolute power over the entire system

• Joining a workgroup or becoming part of a domain is relatively easy in any version of Windows

Joining a Workgroup or Domain in Windows 98

Protocols

• Network protocol software– Takes the incoming data received by the network

card– Keeps it organized– Sends it to the application that needs it– Takes outgoing data from the application and

hands it over to the NIC to be sent out over the network

• The most common protocols used are– NetBEUI– IPX/SPX– TCP/IP– AppleTalk

NetBEUI

• NetBIOS Extended User Interface (NetBEUI) – Small size– High speed– Not routable– Limited to small networks

IPX/SPX

• Internetwork Packet Exchange/ Sequenced Packet Exchange (IPX/SPX)– Developed by Novell– Routable– NWLink is Microsoft’s version

TCP/IP

• Transmission Control Protocol/Internet Protocol (TCP/IP)– Developed by the U.S. Department of Defense– Used in networks of all sizes– Used on the Internet

AppleTalk

• AppleTalk is a proprietary protocol developed by Apple– Used to communicate with older Apple Computers– Apple’s Macintosh OS X supports TCP/IP

Client and Server Software

• Client software– Needed to access data

and resources on a network

– Windows installs Client for Microsoft Networks

• Server software– Any Windows PC may

be turned into a server by enabling sharing of files, folders, and printers

Installing and Configuring a Wired Network

Network Connectivity

• To connect to a network you need– Network Interface Card

• Physical hardware that connects the PC to the network wire

– Protocol• The language the devices will use to communicate

– Network Client• Allows the computer system to speak to the protocol

– In addition, if you would like share your files or printer, you need to enable Microsoft’s File and Print Sharing

Installing a NIC

• When choosing a NIC there are three requirements– Must run at the proper speed (many NICs run at

more than one speed)– Must be for the proper technology

• Ethernet, Token Ring, Fiber optic (FDDI)

– Must fit into your expansion slot• ISA, PCI

• If your NIC does not autoinstall, then use the Add Hardware wizard in Control Panel

Configuring a Network Client

• You need a network client for each type of server NOS– Client for Microsoft Networks

• Alt-click My Network Places (or Network Neighborhood) and choose Properties

• Double-click the Local Area Connection icon (or choose to Create a New Network Connection) and choose Properties

• Client for Microsoft Networks is automatically installed when you install a NIC in Windows

– Client Service for NetWare• Provides access to file and print services on NetWare

servers

Client for Microsoft Networks

NetBEUI

• NetBEUI– Windows 2000: Start Settings Network and

Dialup Connections Double-click the Local Area Connection icon

– Windows 9x/Me: Start Settings Control Panel double-click the Network applet

– Click the Properties button– Install button highlight Protocols and click Add

NetBEUI– Windows XP has dropped support for NetBEUI

NetBEUI

NWLink

• Microsoft’s implementation of IPX/SPX– You’ll also need to install Client Services for

NetWare– Install the same way you install NetBEUI but choose

NWLink instead

Configuring TCP/IP

• TCP/IP is the most widely used protocol stack in networks today– It is the protocol of choice for the Internet but may

also be used on small private networks– TCP/IP is installed just like NetBEUI and NWLink –

just choose Internet Protocol (TCP/IP)– You’ll need to configure and IP address and a

Subnet Mask at the very least

IP Addresses

• Part of an IP address represents the network or subnet (network ID), while the other part represents the individual device (host ID) on that given network or subnet

• Consists of four sets of 8 binary numbers (octets) separated by a period– Called dotted-decimal notation– Examples are: 10.1.209.5, 202.34.16.11– In binary the second example is:

• 11001010.00100010.00010000.00001011

Classes of Addresses

• IP addresses are broken into classes based on the size of the network– Class A IP addresses are for large companies

• The first 8 bits or octet is used to define the network• The other 3 octets are used to define the hosts• The first octet begins with 0

– Class B IP addresses are for medium size companies

• The first two octets define the network• The last two octets define the hosts on each network• The first octet begins with 10

– Class C IP addresses are for smaller companies• The first three octets define the network• The last octet defines the host• The first octet begins with 110

Classes of IP Addresses

• Some addresses are reserved– 127.0.0.1 (the loopback address) is reserved for

testing– Three ranges are reserved for private networks

• 10.0.0.1 thru 10.255.255.255.254• 172.16.0.1 thru 172.31.255.254• 192.168.0.0 thru 192.168.255.254

– One range is reserved for Automatic Private IP Addressing

• 169.254.0.1 thru 169.254.255.254

Classes of IP Addresses

Subnet Mask

• The subnet mask defines which portion of the IP address belongs to the network ID and which part belongs to the host ID– Expressed as a 32-bit number starting with 1s and

ending with 0s– 1s represent a network ID bit and 0s represent a

host ID bit• For example,

11111111.00000000.00000000.0000000 means that the first 8 bits define the network ID and the last 24 bits define the host ID

– It is associated with an IP address

TCP/IP Services

• TCP/IP is an entire suite of protocols that offers TCP/IP Services such as– Hypertext Transfer Protocol (HTTP) used on the

World Wide Web– Telnet used to access remote systems– Ping to check communication

• TCP/IP is used to link multiple networks (Local Area Networks or LANs) with other networks to form an entire Wide Area Network (WAN)– Routers are used to route traffic among the LANs

PING, LAN and WAN

TCP/IP Settings

• IP address• Subnet Mask• Default Gateway

– The address of a machine (usually a router) that will deliver messages to hosts outside of your local segment or subnet

TCP/IP Settings

• Domain Name Service (DNS)– To reach any host on a TCP/IP network you need to

know the IP address– Instead of remembering IP addresses you may

simply remember a user-friendly name– DNS is a table that equates user-friendly names to

actual IP addresses

TCP/IP Settings

• Dynamic Host Configuration Protocol (DHCP)– Instead of manually configuring

the TCP/IP settings on each computer (static settings), you may configure one computer to manage the assignments for you

– Computers that handle this use DHCP and are called DHCP servers

– On the client computer just choose to “Obtain an IP address automatically”

TCP/IP Settings

• Windows Internet Name Service (WINS)– Enables Windows network names to be correlated

to IP addresses (like DNS does for Internet names)– Define the IP address of the WINS server– Windows 2000/XP uses a dynamic DNS instead of

WINS

TCP/IP Tools: Ping

• Ping– Tests connectivity to a remote host

TCP/IP Tools: WINIPCFG

• WINIPCFG – Displays your TCP/IP settings in Windows 9x/Me– Release and Renew allows you to get new TCP/IP

information from a DHCP server

TCP/IP Tools: ipconfig

• IPCONFIG– Displays your TCP/IP settings in Windows

NT/2000/XP– Release and Renew allows you to get new TCP/IP

information from a DHCP server

TCP/IP Tools: nslookup

• NSLOOKUP– Determines the name of a DNS server among other

things• Type exit to return to the command prompt

TCP/IP Tools: tracert

• TRACERT– Shows the route a packet takes to its destination

TCP/IP Tools: APIPA

• Automatic Private IP Addressing (APIPA)– When a client cannot obtain an IP address

automatically, Windows 2000/XP will automatically assign its own IP address from the range 169.254.0.0 thru 169.254.255.254 with a subnet mask of 255.255.0.0

– APIPA is of value when a DHCP server is not available – it allows the hosts on the LAN to talk to each other even though they can’t reach anyone outside their LAN

Sharing Drives and Folders

• To share a drive or folder, alt-click it and select Sharing– Share name is the name others will see on the

network– Windows 9x/Me allows you to define what a user

may do: Read Only, Full, or Depends on Password– Windows NT/2000/XP using NTFS-formatted drives

allows for much greater and precise control• Set the network (Sharing tab) permissions to Full

Control• Then use NTFS permissions (Security tab) to exercise

more precise control over who accesses the shared resource and how they access them

Sharing Drives and Folders

Accessing Shared Resources

• Access shared drives or folders using Network Neighborhood (Windows NT and 9x) or My Network Places (Windows Me, 2000, XP)– You may also map a drive letter to a shared drive

or folder– Windows 2000 allows you to add a network icon

instead of using a drive letter– Windows XP adds a menu option

UNC

• Universal Naming Convention (UNC) allows you to access network resources as follows

\\SERVER1\FREDC

Computer name

Share name

Sharing Printers

• To share a printer, just alt-click on the printer and choose Sharing

• To access the printer, use the Add Printer icon and select Network printer instead of Local printer

Installing and Configuring a Wireless Network

Introduction

• Wireless networks are growing in popularity

• Instead of cables, wireless networks use either radio waves or beams of infrared light to communicate with each other

• Most of today’s wireless networks are based on the IEEE 802.11 standard

Infrared Connections

• Infrared transceiver ports are standard on many portable computer, PDAs, and high-end printers– Used to connect local devices to each other without

using a cable

Wireless Networking Components

• Connection components for wider access– PCI cards that accept wireless

PC cards– External USB wireless NICs

Wireless Access Point

• Wireless Access Point (WAP)– Acts like a hub to the wireless hosts in the area

Wireless Networking Software

• Wireless devices use the same networking clients and protocol as wired networks– Use CSMA/CD but have difficulty detecting data

collisions• Another option is using Request to Send/Clear to

Send (RTS/CTS) where the sending node issues an RTS to the receiving node, who replies with a CTS

• Wireless networking software is PnP– Use a utility (usually provided with the wireless NIC

or built into Windows) to configure the Service Set Identifier (SSID), or network name

Wireless Configuration Utility

Wireless Network Modes

• Ad hoc Mode– Each wireless node is in

direct contact with each other in a decentralized free-for-all

– Form an Independent Basic Service Set (IBSS)

– Called peer-to-peer mode

– Good for a few computers or temporary network

Wireless Network Modes

• Infrastructure Mode– Use one or more WAPs

to connect wireless nodes to a wired network segment

– A single WAP is called a Basic Service Set (BSS)

– Additional WAPs create an Extended Basic Service Set (EBSS)

Wireless Networking Security

• Service Set Identifier (SSID)– Configure a unique SSID or network name– Each node needs to have the same SSID– Not very secure but better than nothing

• MAC Filtering– Filtering based on each host’s MAC address burned

into their NIC– Creates a type of accepted user

Wireless Network Security

• Wireless Equivalency Privacy (WEP)– Encrypts data using 40-bit or 104-bit encryption– Provides authentication based on MAC addresses

but not users– Encrypts only OSI layers 1 and 2

• Wi-Fi Protected Access (WPA)– User authentication using the Extensible

Authentication Protocol (EAP)– Uses encryption key integrity-checking

• IEEE 802.11i– Upcoming new security standard

Wireless Networking Standards

• IEEE 802.11-Based Wireless Networking– Wireless Ethernet standard using spread-spectrum

radio waves– Broadcast and receive at 2.4 GHz

• 802.11a uses 5 GHz

– The original standard has been extended to form the Shared Wireless Access Protocol (SWAP) used in HomeRF networks

802.11 Standards

Wireless Network Standards

• Infrared Wireless Networking– Simple way to share data without adding any additional

hardware or software– Uses the Infrared Data Association (IrDA) protocol

• Included in Windows 95 and higher– Line-of-sight required– No authentication or encryption

• But then you can’t be over 1 meter away

Configuring Wireless Networks

• Physically installing a wireless NIC is the same as installing a wired NIC

• Install the wireless network configuration utility to configure additional parameters– Windows XP has configuration parameters built-in

• The more important issue is authentication and security


• Wi-Fi and HomeRF– Ad hoc

• Each wireless node needs to be configured with the same network name (SSID)

• May need to select a common channel• Configure unique host IP addresses• Configure File and Printer Sharing

– Infrastructure modes• Requires a wireless access point (WAP)• All nodes need to be configured with the same SSID• Configure the WAP with clients that match the chosen

options


• Configuring a Wireless Access Point (WAP) is usually done through a web browser– Enter the WAP’s default IP address (see your

documentation or try 192.168.1.1) in your browser– Enter the default administrative password (in your

documentation) to log in• The next few slides show some screen shots of the

configuration pages


• Encryption screen on client wireless network adapter configuration utility


• Infrared– About the only thing to do is to confirm in your

network protocol configuration screen that you have the IrDA protocol installed and enabled

– To transfer files just alt-click the file in Windows Explorer and choose Send To Infrared Recipient

– To network two computers just choose Connect Directly to Another Computer when choosing the connection type

Troubleshooting Networks


1. Verify the symptom– Talk with the use to try to get a solid description of

the symptoms

2. When did it happen?– Does it happen a boot, when the OS loads, or after

the system has been running for awhile?

3. What has changed?– Try to find out if anything has changed – even

recent changes before the problem began occurring


4. Check the environment– Heat, humidity, dirt– What OS? What applications? Do others use the

computer?

5. Reproduce the problem– If a problem happens only once, it’s not a problem– Otherwise, try to make the problem happen again

6. Isolate the symptom– With hardware remove parts until you find the

suspect one– With software remove background programs or

boot into Safe Mode


7. Separate hardware from software– Replace the suspect hardware with known good

hardware – if that doesn’t solve the problem, then it’s probably software related

– Uninstall the suspect software and reinstall it– Install the latest patch or upgrade– Check for viruses

8. Research– Use the Internet as a great tool

9. Make the fix and test– Keep track of what you did so that you may return

to the previous state if the fix does not work

Mike’s Four-Layer Model

• Hardware– Check the hardware starting with the physical layer

• Protocols– Is it installed and configured properly?

• Network– Servers and non-servers– Check users and groups, share names

• Shared resources– Make sure the resource has been properly shared– Check the access allowed

Bluetooth

• Bluetooth is designed to replace all those cables connecting peripheral devices together – keyboards, mouse, printer, speakers, scanner– Acceptable for quick file transfers– Acceptable for browsing the Internet– Hardware comes integrated on most new portable

electronic devices or as an internal or external adapter

– Configuration is PnP– Bluetooth access points use a web browser for

configuration

Chapter 9: Networking

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Transcript of Chapter 9: Networking