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Jan 20, 2015




  • 1. Introduction to Networking Definitions and Terms

2. 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.

3. Networking Overview

  • Anetworkis 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.

4. 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 to a 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.

5. Types of Local Area Networks Server-Based Network Network Figure # 1 6. Types of Local Area Networks Network Figure # 2 Peer-to Peer Network 7. Network Topologies

  • Network Topology Maps of how the physical or logical paths of network devices connect. The three major topologies arestar ,ring , andbus .
  • 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 at each 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.

8. Network Topologies Network Figure # 3 Hub/Switch 9. Network Topologies Network Figure # 4 Star Topology 10. Network Topologies Logical Ring Topology Network Figure # 5 11. Network Topologies Network Figure # 6 Bus Topology 12. Network Topologies Network Table # 1Network Topologies 13. Network Cabling

  • Cable is normally used as a medium for transporting network data. The most common types aretwisted-pairandfiber-optic , althoughcoaxis still used in some old networks.
  • Twisted-Pair Cable Network cable of eight copper wires twisted into four pairs to preventcrosstalk .
    • 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.

14. 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 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.
  • 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.

15. Network Cabling Network Figure # 7 UTP Cable 16. Network Cabling Network Figure # 11 Fiber-Optic Cable 17. Network Cabling Network Figure # 12 Coax Cable with Connector 18. 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 onenetworked device to another in a ring topology.

19. Ethernet Issues and Concepts

  • Two types of transmissions used in Ethernet networks:
  • Half Duplex A serial device setting that 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 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.

20. Layers of the Internet

  • One logical view of the Internet has five layers
    • Physical Layer Layer 1 this model defines how bits are sent and received 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 liketelnet ,ftp , etc.

21. 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.

22. 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.

23. 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.

24. Network Addressing

  • Ho