Introduction to Networking

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• Introduction to Networking
• Chapter 10

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Learn how to

• Define the term networking and list three
  critical components.
• Describe the five basic topologies.
• Define the seven layers of the OSI model and the
  protocols that use it.
• Describe the differences among LAN, MAN, and WAN.
• Describe the physical network components.

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• Understanding Networks

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Networks

• A network is the connection of two or more
  digital devices for communicating, transferring,
  or obtaining data.
• The act of communicating over a network is called
  networking.

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Networking
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Characteristics of a Network

• All networks require
• A physical connection (or wireless connection).
• A set of communication rules called protocols.
• One or more network services that will receive
  the communication.

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Mainframe/Terminal Model

• The mainframe/terminal model
• A mainframe is a centralized computer to which
  users connect to obtain network services.
• The terminal is a device with a
  keyboard, which you use to type commands or
  enter data to communicate with the mainframe
  computer.

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Client-Server Model

• Client-server refers to the manner in which
  computers exchange information by sending it (as
  servers) and receiving it (as clients).
• Computers can serve dual roles as both servers
  and clients.

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Multi-Tier

• Large organizations may subdivide complex
  applications into multiple stages called tiers.
• Multi-tier computing typically includes three
  tiers consisting of the user interface tier, the
  business tier, and the database tier.

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Peer-to-Peer Model

• Peer-to-peer (P2P) is a network architecture in
  which each workstation has equal
  responsibilities.

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Enterprise Model

• Enterprise model refers to networking within
  large organizations that dedicate entire servers
  to handling important tasks.
• Serving mail
• Hosting databases
• Managing security
• Routing network traffic

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Push-Pull Technology

• The push-pull metaphor
• Pull means that you ask for the information.
• When you click a hyperlink.
• Push means that the information is being provided
  to you.
• When stock quotes are automatically updated on
  your desktop or when weather is automated updated
  on your desktop.
• See www.weatherbug.com

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Complex Network
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Network Operating Systems

• A network operating system is the software that
  adds to a computer the functions required for
  connecting computers together for networking.
• Microsoft Windows
• UNIX and Linux
• Mac OS
• Novel NetWare

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Microsoft Windows

• Microsoft Windows is the most wide spread network
  operating system.
• Every version of Windows contains networking
  capability, but some versions do not support all
  network services.
• For a history of Windows server products, visit
  www.microsoft.com/windows/winhistoryserver.mspx

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UNIX and Linux

• The UNIX and Linux operating systems support the
  full range of networking services, including both
  client- and server-side components.
• The Open Group holds the trademark and defines
  the official version of UNIX at
  www.unix-systems.org
• Linux is an open source version of UNIX
• To learn more, go to www.linux.org

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Mac OS

• The Macintosh OS X operating system has
  networking built in.
• Behind the Macintosh user interface is a
  UNIX-based operating system.
• To learn more, go to www.apple.com/macosx/features
  /unix

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Novell NetWare

• NetWare is a PC-based local area networking
  product that was one of the most dominant network
  operating systems during the decade following its
  invention in 1983.
• However, when Microsoft marketed Windows NT in
  1993, Novell NetWares market share dropped.
• For more information, go to www.novell.com/product
  s/netware

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Classifying Network Topologies
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Network Topologies

• A networks geographical shape is referred to as
  the networks topology.
• The five kinds of network topologies are
• Bus topology
• Ring topology
• Star topology
• Hybrid topology
• Mesh topology

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Bus Topology

• The bus topology has a single cable, called the
  bus or the trunk, to which every device on the
  network connects.
• All of the messages on the bus pass by each
  device, or node, on the bus.
• It uses inexpensive coaxial cable that is easy to
  install.
• A break anywhere along the cable causes all
  network traffic to stop.

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Ring Topology

• A ring topology forms when you connect a
  networks nodes in a circle.
• Messages flow in a single direction.
• A small packet called a token circulates the ring
  a device must have the token to use the
  network.

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Star Topology

• In a star topology, each device in the network
  connects to a central hub, which distributes
  messages from one node to another.
• Provides centralized control
• Easy expansion
• Fault tolerance

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Hybrid Topology

• A hybrid topology in a network employs more than
  one topology to connect devices.

Star Bus topology
Star Ring topology
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Mesh Topology

• In a mesh topology, multiple connections are
  made.
• In mission-critical operations, you want as much
  redundancy as possible so that if one part of
  the network goes down, the packets can find an
  alternate path to their destination.

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Adopting Network Protocols
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Protocol

• A protocol is a set of rules that define how
  computers communicate with each other.
• The International Standards Organization (ISO)
  developed an international standard called the
  Open System Interconnection (OSI) Reference Model
  (OSI/RM).

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OSI Reference Model

• This model comprises of seven layers that
  describe the way data is shared on a network.
• Suppose you just clicked on a link on a Web page.
  The following slides describe the process from
  one layer to another.
• Data is passed down from Layer 7 to Layer 1, is
  then transmitted over the medium, and then goes
  back up from Layer 1 to Layer 7 in the receiving
  device.
• Headers are added at each layer.

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Layer 7 Application

• Through an Application Programming Interface
  (API), the browser informs the Application Layer
  of your request.
• The Application Layer begins to form the packet
  that will eventually travel across the network.

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Layer 6 Presentation

• The Presentation Layer translates the data into a
  standard network data format.
• It can use data compression to streamline the
  packet so it does not consume unnecessary
  bandwidth on the network.
• It can also encrypt the data for sensitive data
  transmissions.

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Layer 5 Session

• The Session Layer negotiates the connection that
  will be made between the two computers exchanging
  data.
• It inserts a checkpoint, which is a marker used
  to signal that a certain amount of the data has
  arrived all right.

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Layer 4 Transport

• The Transport Layer works to ensure that the data
  arrives reliably at its destination.
• If the amount of data is large, the data is
  split into fragments that are numbered
  sequentially.

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Layer 3 Network

• The Network Layer organizes data into datagrams
  consisting of the data from the Transport Layer
  and routing information such as the source and
  destination addresses.

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Layer 2 Datalink

• The Data Link Layer transforms the data into data
  frames.
• It consists of two sublayers
• Logical Link Control (LLC)
• Performs error checking and regulates the flow
  of data.
• Media Access Control (MAC)
• Handles the actual placement of the packets onto
  the Physical Layer.

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CRC

• The Data Link layer also calculates a cyclic
  redundancy check (CRC) based on the information
  in the frame.
• The receiving machine calculates its own CRC and
  compares it to the value in the frame. If they do
  not match, the frame is corrupt and discarded.

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Layer 1 Physical

• The Physical Layer transforms the 0s and 1s
  into signals that flow over the transmission
  media.
• At the receiving end, the Physical Layer converts
  these signals back into 0s and 1s and passes
  them up to the Data Link Layer.

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Communication
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To help you remember
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Protocol Suites

• The term protocol suite refers to a collection of
  protocols that work together to conform to a
  multilayered protocol standard, such as the
  OSI/RM.
• Six major protocol suites follow the OSI/RM
• TCP/IP
• NetBEUI
• IPX/SPX
• AppleTalk
• DLC
• SNA

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TCP/IP

• TCP/IP is the Internets protocol suite.
• Transport Control Protocol (TCP)
• Manages the Transport Layer
• Internet Protocol (IP)
• Handles the routing on the Network Layer

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NetBEUI

• NetBEUI stands for NetBIOS Extended User
  Interface
• NetBIOS stands for Network Basic Input/Output
  System
• Not routable

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IPX/SPX

• IPX/SPX stands for Internetwork Packet Exchange
  (IPX) and Sequenced Packet Exchange (SPX).
• Developed by Novell for use with the NetWare
  network operating system.

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AppleTalk

• AppleTalk is the legacy protocol suite for
  peer-to-peer networking on local networks of
  Macintosh computers.

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DLC

• IBM invented Data Link Control (DLC) to enable
  microcomputers to connect as clients to legacy
  mainframes.
• Still used by Hewlett-Packard printers that have
  Network Interface Cards (NICs).

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SNA

• Systems Network Architecture (SNA) is a protocol
  suite for connecting different kinds of networks.

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Combining Protocols

• Most computers run more than one networking
  protocol.
• The process of assigning a protocol to a Network
  Interface Card (NIC) is called protocol binding.
• The binding order is the order in which your
  computer tries protocols when attempting to
  communicate over the network.

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Creating LANs, MANs, and WANs
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LAN

• A local area network (LAN) is the connection of
  two or more computer devices for networking
  within a relatively small area.

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MAN

• A metropolitan area network (MAN) connects local
  networks across a larger geographical region.
• The term metropolitan implies that MANs cover an
  area the size of a city.

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WAN

• A wide area network (WAN) uses high-speed
  transmission lines to connect MANs and LANs over
  large geographical areas.

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Project 802

• The Institute of Electrical and Electronic
  Engineers (IEEE, pronounced I triple-E) is in
  charge of defining the networking standards that
  connect devices to form different kinds of local
  and metropolitan area networks.
• Called Project 802.

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Project 802
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IEEE 802.2

• The IEEE 802.2 standard is the Logical Link
  Control (LLC) sublayer of the OSI/RM Data Link
  Layer.

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IEEE 802.3

• The IEEE 802.3 standard defines Ethernet, which
  is the most popular method of local area
  networking.
• Defines CSMA/CD, which stands for Carrier Sense
  Multiple Access with Collision Detection.
• Ethernet works by detecting the data collisions
  that can occur when two or more devices use a
  data channel simultaneously.

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Ethernet

• The maximum speed of an ordinary 802.3 Ethernet
  is 10 Mbps.
• Fast Ethernet runs at 100 Mbps.
• Gigabit Ethernet runs at 1000 Mpbs.

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IEEE 802.5

• The IEEE 802.5 standard defines token ring, which
  derives from IBMs local area network design in
  which a token travels continually around the
  cable ring to which the network devices are
  attached.
• A device can send data only when it has the
  token.
• Each device attaches to a central connecting
  point called a Multi-Station Access Unit (MAU).

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IEEE 802.12

• The IEEE 802.12 standard defines a Demand
  Priority Access LAN that is known in the
  marketplace as 100VG-AnyLAN.
• 100VG means that the network is designed to
  transmit at a speed of 100 Mbps over voice grade
  (VG) telephone wiring.
• AnyLAN refers to the fact that this network can
  handle packets framed for transmission on either
  Ethernet or token-ring networks.

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FDDI

• Fiber Distributed Data Interface (FDDI) uses
  fiber optics to create a very fast network.
• Uses two counter-rotating token rings.
• Due to its high reliability, FDDI is often used
  for backbones (network cables that act as the
  primary pathways for traffic).

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FDDI
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WANs

• A wide area network (WAN) is the connection of
  two or more LANs that can be located in different
  buildings, cities, countries, or continents.
• The local networks can be connected by
• Telephone lines
• ISDN
• Broadband
• Frame Relay
• Asynchronous Transfer Mode (ATM)

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X.25

• X.25 enables data to be transmitted over the
  packet-switched networks (PSNs) of the telephone
  companies.
• Legacy WAN protocol with extensive error
  checking.
• Used by some for credit-card swiping and
  automated bank machines.

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Frame Relay

• Frame Relay is a streamlined version of X.25.
• No error checking.
• Connections can be
• Switched virtual circuit (SVC) created for each
  data transfer and terminated when the data
  transfer is complete.
• Permanent virtual circuit (PVC) that is
  constantly on.
• Bandwidth on demand allows customers to choose
  their connection speed.

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ATM

• Asynchronous Transfer Mode (ATM) is an ITU
  standard for cell relay that can transmit voice,
  video, or data in small, fixed-size 53-byte
  chunks called cells.
• Asynchronous means that the cells do not have to
  line up and wait to be transmitted sequentially
  over a single connection.

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ATM
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NAP

• A network access point (NAP) is a junction that
  provides direct access to the traffic on a
  network.
• The three major NAPs used by the ISPs are located
  in New York, Chicago, and San Francisco.

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T-Carriers

• NAPs often use the T-carrier system to connect a
  LAN to a WAN.
• Organizations that cannot afford the cost of a
  full T1 can lease a fractional T1.

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E-Carriers

• E-carriers are used in Europe.

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WAP

• Wireless access point (WAP) refers to wireless
  network junctions that enable workstations to
  communicate without cables.

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NAT

• Network address translation (NAT) transforms the
  IP addresses used for internal traffic into a
  second set of addresses for external traffic.
• NAT hides internal addresses, acting as a
  firewall against attacks.
• Multiple internal addresses can be translated
  into fewer external addresses.

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Network Cards

• Each workstation must have a Network Interface
  Card (NIC).
• On FDDI equipment, the network interface is
  called a MIC, which stands for Media Interface
  Card.
• On wide area networking equipment, the network
  interface is called a WIC, for WAN interface card.

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Network Components

• Users perform work on clients called
  workstations.
• A concentrator is an Ethernet multiport repeater
  used to connect multiple Ethernet devices to a
  single Ethernet cable.
• A hub serves as the center of a star network
  topology (Ethernet multiport repeater).

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Network Components

• A repeater interconnects two network cables so
  they can be treated as a single cable.
• Allows one to extend the length of the cable.
• A switch filters, forwards, and floods frames
  based on the destination MAC address of each
  frame.
• To flood is to pass traffic out all of the
  switchs connections except for the incoming
  interface through which the traffic was received.

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Network Components

• A bridge is used to connect two network segments
  and pass packets between them based on the
  destination MAC address of each frame.
• A switch is a multiport bridge.
• A router forwards network traffic along the
  optimal path based on information in the packets
  Network Layer header.

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Network Components

• A bridge router (brouter) is a relay that
  functions as both a router and a bridge.
• A gateway is a computer that routes traffic from
  a workstation on an internal network to an
  external network such as the Internet.

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Coaxial Cabling

• Coaxial cable, also known as coax, consists of a
  cylindrically braided outer conductor that
  surrounds and shields a single solid inner copper
  wire conductor.

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Coaxial Cabling

• Coaxial cable comes in two forms

• Thinnet
• Thin coaxial cable
• Used in 10Base2 Ethernet networks
• Cable segments up to 185 meters in length

• Thicknet
• Thick coaxial cable
• Used in 10Base5 Ethernet networks
• Cable segments up to 500 meters in length

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Coaxial Cabling

• Coaxial cables use the British Naval Connector
  (BNC) to plug the cables into workstations, hubs,
  and other kinds of network devices.

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Twisted Pair Cabling

• Twisted pair is a transmission medium consisting
  of two insulated wires that are twisted together
  to create a double helix that reduces noise
  levels and eliminates crosstalk between the
  wires.

• Unshielded twisted pair (UTP)

• Shielded twisted pair (STP) has an extra layer of
  insulation

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Twisted Pair Cabling

• Twisted-pair cabling is broken into categories.
• CAT 5 means category 5.
• The wires terminate in an RJ-45 connector.

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Twisted Pair Cabling
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Twisted Pair Cabling

• Twisted pair cables consist of four pairs of
  wires with RJ-45 connectors at the end.

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Fiber Optic Cabling

• Fiber optics is a transmission method that
  transmits light-modulated video, voice, or data
  signals through hair-thin strands of glass called
  fibers.
• These strands are encased by a layer of
  Kevlar-reinforced reflective material called
  cladding, which keeps the light inside the fiber.

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Wireless Media

• Includes cellular, radio, microwave, satellite,
  and infrared signals.
• Network nodes that use wireless connections must
  have a wireless NIC, which connects to a
  transceiver known as a wireless access point
  (WAP).
• Defined by the 802.11 standards.
• For more information, go to www.microsoft.com/wind
  owsxp/mediacenter

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