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Networking Fundamentals


The Open Systems Interconnection ... the network to work effectively. OSI Model Overview A message begins at the top application layer and moves down the OSI layers ... – PowerPoint PPT presentation

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Title: Networking Fundamentals

Networking Fundamentals
  • M.Vineeth Kumar, MS.,MCSA.,CCNA,.CQFS

Networking Fundamentals
  • 1 Introduction to PC Networking
  • 2 Types of Networks
  • 3 Adding a Network Interface Card (NIC)
  • 4 Physical Components of a Network
  • 5 LAN Architectures
  • 6 Networking Protocols and the OSI Model
  • 7 TCP/IP Utilities
  • 8 Connecting to the Internet

Introduction to PC Networking
Defining a Computer Network
  • A computer network allows users to communicate
    with other users on the same network by
    transmitting data on the cables used to connect
  • A computer network is defined as having two or
    more devices (such as workstations, printers, or
    servers) that are linked together for the purpose
    of sharing information, resources, or both.

Defining a Computer Network
  • A network consists of many overlapping systems,
    such as cabling, addressing schemes, or
  • The layers work together to transmit and receive
  • The Open Systems Interconnection (OSI) reference
    model, was created to define these multiple

File, Print, and Application Services
  • Computer networks offer file and print services.
  • In networks, different computers take on
    specialized roles or functions.
  • Once connected, one or more computers in the
    network can function as network file servers.
  • The server is a repository for files that can be
    accessed and shared across the network by many

File, Print, and Application Services
  • All network operating systems offer file and
    print services.
  • Sharing information, collaborating on projects,
    and providing access to input and output devices
    are common services of computer networks.

Mail Services
  • E-mail services work like the postal system, with
    one computer taking on the function of post
  • The user e-mail account operates like a post
    office box, where mail is held for the user until
    it is picked up over the network by an e-mail
    client program running in the user system.
  • The e-mail is sent from the client computer to
    the server, which acts as the post office. The
    server sends it to the e-mail address.

Directory and Name Services
  • To enable users and systems on the network to
    find the services they require, computer networks
    make use of directories and name services.

Directory and Name Services
  • Directory and name services make a network easier
    to use.
  • After the initial setup of the directory or name
    service, this translation takes place
  • In addition to their ease of use, they also make
    the network more flexible.

The Internet
  • The Internet is a worldwide public network of
    networks, interconnecting thousands of smaller
    networks to form one large web of
  • The Internet functions like a highway to
    facilitate exchange between geographically
    separated users, organizations, and branches of

The Internet
  • The phrase information superhighway describes
    the benefit of the Internet to business and
    private communication.
  • The Internet breaks down barriers of time and
    space, enabling the sharing of information around
    the globe almost instantaneously.

Network Administration
  • The ongoing task of network administration is to
    maintain and adapt the network to changing
  • Network administrator responsibilities include
  • Setting up new user accounts and services
  • Monitoring network performance
  • Repairing network failures

Simplex, Half-Duplex, and Full-Duplex
  • Simplex transmission is a single one-way baseband
  • It is also called unidirectional because the
    signal travels in only one direction.
  • An example of simplex transmission is the signal
    sent from the cable TV station to the home

Simplex, Half-Duplex, and Full-Duplex
  • This means that only one side can transmit at a
  • Two-way radios, such as Citizens Band (CB) and
    police/emergency communications mobile radios,
    work with half-duplex transmissions.

Simplex, Half-Duplex, and Full-Duplex
  • Traffic can travel in both directions at the same
  • A regular telephone conversation is an example of
    full-duplex communication. Both parties can talk
    at the same time, and the person talking on the
    other end can still be heard by the other party
    while they are talking.

Types of Networks
  • By using local-area network (LAN) and wide-area
    network (WAN) technologies, many computers are
    interconnected to provide services to their
  • In providing services, networked computers take
    on different roles or functions in relation to
    each other.
  • Some types of applications require computers to
    function as equal partners. Other types of
    applications distribute work so that one computer
    functions to serve a number of others in an
    unequal relationship.

Peer-to-Peer Networks
  • In a peer-to-peer network, the networked
    computers act as equal partners, or peers, to
    each other.
  • As peers, each computer can take on the client
    function or the server function alternately.

Client/Server Networks
  • In a client/server network arrangement, network
    services are located in a dedicated computer
    whose only function is to respond to the requests
    of clients.
  • The server contains the file, print, application,
    security, and other services in a central
    computer that is continuously available to
    respond to client requests.

Local-Area Networks (LANs)
  • A local-area network (LAN) can connect many
    computers in a relatively small geographical area
    such as a home, an office, or a campus.
  • It allows users to access high bandwidth media
    like the Internet and allows users to share
    devices such as printers.

Local-Area Networks (LANs)
  • The general shape or layout of a LAN is called
    its topology.
  • Topology defines the structure of the network.
    This includes the physical topology which is the
    actual layout of the wire or media, and the
    logical topology which is how the media is
    accessed by the hosts.

Wide-Area Networks (WANs)
  • A WAN, as the name implies, is designed to work
    over a larger area than a LAN.
  • A WAN uses point-to-point or point to multipoint,
    serial communications lines.
  • Point-to-point lines connect only two locations,
    one on each side of the line. Point-to-multipoint
    lines connect one location on one side of the
    line to multiple locations on the other side.

Wide-Area Networks (WANs)
  • The following are some of the more common WAN
  • Modems
  • Integrated Services Digital Network (ISDN)
  • Digital subscriber line (DSL)
  • Frame Relay
  • Asynchronous Transfer Mode (ATM)
  • The T (US) and E (Europe) Carrier series (T1, E1,
    T3, E3, and so on)
  • Synchronous Optical Network (SONET)

Wide-Area Networks (WANs)
  • Connections across WAN lines may be temporary or
  • Telephone or dialup lines, might make a temporary
    connection to a remote network from a computer in
    a home or small office.
  • In both temporary and permanent cases, computers
    that connect over wide area circuits must use a
    modem or channel service unit/data service unit
    (CSU/DSU) at each end of the connection.

Wide-Area Networks (WANs)
  • The public telephone system, sometimes referred
    to as plain old telephone service (POTS), is a
    circuit-switched communications network.
  • When a telephone call is placed in this type of
    network, only one physical path is used between
    the telephones for the duration of that call.
  • This pathway is maintained for the exclusive use
    of the call, until the connection is ended and
    the telephone is hung up.

Wide-Area Networks (WANs)
  • In a packet-switched network, each individual
    packet of data can take a different route and no
    dedicated pathway or circuit is established.

Adding a Network Interface Card (NIC)
What is a NIC?
  • A network interface card (NIC) is a device that
    plugs into a motherboard and provides ports for
    the network cable connections.
  • It is the computer interface with the LAN.
  • The NIC communicates with the network through
    serial connections and communicates with the
    computer through parallel connections.

Setting the IP Address
  • In a (TCP/IP)-based LAN, PCs use an IP address to
    identify each other.
  • These addresses allow computers that are attached
    to the network to locate each other.
  • IP addresses for hosts on a LAN can be assigned
    in two ways
  • Manually assigned by the network administrator
  • Assigned by a Dynamic Host Configuration Protocol
    (DHCP) server

DHCP Servers
  • The most common and efficient way for computers
    on a large network to obtain an IP address is
    through a Dynamic Host Configuration Protocol
    (DHCP) server.
  • DHCP is a software utility that runs on a
    computer and is designed to assign IP addresses
    to PCs.
  • When the DHCP server receives a request from a
    host, it selects IP address information from a
    set of predefined addresses that are stored in
    its database.

Default Gateway
  • A computer located on one network segment that is
    trying to talk to another computer on a different
    segment sends the data through a default gateway.
  • The default gateway is the near side interface
    of the router, the interface on the router to
    which the network segment or wire of the local
    computer is attached.

Domain Name System
  • Most hosts are identified on the Internet by
    friendly computer names known as domain names.
  • The Domain Name System (DNS) is used to translate
    computer names such as to their
    corresponding unique IP address.
  • The DNS server keeps records that map computer
    (host) names and their corresponding IP address.
    These record types are all combined in the DNS

Physical Components of a Network
Network Topologies
  • The network topology defines the way in which
    computers, printers, and other devices are
    connected. A network topology describes the
    layout of the wire and devices as well as the
    paths used by data transmissions.
  • Commonly referred to as a linear bus, all the
    devices on a bus topology are connected by one
    single cable.

Network Topologies
  • The star topology is the most commonly used
    architecture in Ethernet LANs.
  • When installed, the star topology resembles
    spokes in a bicycle wheel.
  • Larger networks use the extended star topology.
    When used with network devices that filter frames
    or packets, like bridges, switches, and routers,
    this topology significantly reduces the traffic
    on the wires by sending packets only to the wires
    of the destination host.

Network Topologies
  • A frame travels around the ring, stopping at each
    node. If a node wants to transmit data, it adds
    the data as well as the destination address to
    the frame.
  • The frame then continues around the ring until it
    finds the destination node, which takes the data
    out of the frame.
  • Single ring All the devices on the network
    share a single cable
  • Dual ring The dual ring topology allows data to
    be sent in both directions although only one ring
    is used at a time.

Network Topologies
  • The mesh topology connects all devices (nodes) to
    each other for redundancy and fault tolerance.
  • It is used in WANs to interconnect LANs and for
    mission critical networks like those used by
  • Implementing the mesh topology is expensive and

Physical versus Logical Topology
  • Networks have both a physical and logical
  • Physical topology the layout of the devices and
  • Logical topology the paths that signals travel
    from one point on the network to another.
  • The way in which data accesses media and
    transmits packets across it.

Networking Media
  • Networking media can be defined simply as the
    means by which signals (data) are sent from one
    computer to another (either by cable or wireless
  • Coaxial cable is a copper-cored cable surrounded
    by a heavy shielding and is used to connect
    computers in a network.
  • There are several types of coaxial cable,
    including thicknet, thinnet, RG-59 (standard
    cable for cable TV), and RG-6 (used in video

Networking Media
  • Twisted-pair is a type of cabling that is used
    for telephone communications and most modern
    Ethernet networks.
  • A pair of wires forms a circuit that can transmit
    data. The pairs are twisted to provide protection
    against crosstalk, the noise generated by
    adjacent pairs.
  • There are two basic types, shielded twisted-pair
    (STP) and unshielded twisted-pair (UTP).

Networking Media
  • UTP comes in several categories that are based on
    the number of wires and number of twists in those
  • Category 3 is the wiring used primarily for
    telephone connections.
  • Category 5 and Category 5e are currently the most
    common Ethernet cables used.

Networking Media
  • Fiber-optic cable is a networking medium capable
    of conducting modulated light transmissions.
  • Fiber-optic refers to cabling that has a core of
    strands of glass or plastic (instead of copper),
    through which light pulses carry signals.
  • Signals that represent data are converted into
    beams of light.

Networking Media
  • If the cost of running cables is too high or
    computers need to be movable without being
    tethered to cables, wireless is an alternative
    method of connecting a LAN.
  • Wireless networks use radio frequency (RF),
    laser, infrared (IR), and satellite/microwaves to
    carry signals from one computer to another
    without a permanent cable connection.

Common Networking Devices
  • A hub is a device that is used to extend an
    Ethernet wire to allow more devices to
    communicate with each other.
  • Hubs are most commonly used in Ethernet 10BASE-T
    or 100BASE-T networks, although there are other
    network architectures that use them.

Common Networking Devices
  • Bridges connect network segments.
  • The basic functionality of the bridge resides in
    its ability to make intelligent decisions about
    whether to pass signals on to the next segment of
    a network.
  • A switch is a more sophisticated device than a
    bridge, although the basic function of the switch
    is deceptively simple.
  • Ethernet switches are becoming popular
    connectivity solutions because they increase
    network performance.

Common Networking Devices
  • Routers are slower than bridges and switches, but
    make smart decisions on how to route (or send)
    packets received on one port to a network on
    another port.
  • Routers contain tables of network addresses along
    with optimal destination routes to other

Server Components
  • Server components are those components that are
    used exclusively with the network server. End
    users depend on the server to provide the
    services required.
  • To keep the server running at it is optimal
    performance, a higher level of preventive
    maintenance must be maintained.

LAN Architectures
  • The Ethernet architecture is based on the IEEE
    802.3 standard. The IEEE 802.3 standard specifies
    that a network implements the Carrier Sense
    Multiple Access with Collision Detection
    (CSMA/CD) access control method.
  • Standard transfer rates are 10 Mbps or 100 Mbps,
    but new standards provide for gigabit Ethernet,
    which are capable of attaining speeds up to 1
    Gbps over fiber-optic cable or other high-speed

  • 10BASE-T uses a star topology.
  • The 10 stands for the common transmission speed
    of 10 MBps, the "BASE" stands for baseband mode,
    and the "T" stands for twisted pair cabling.

  • 100BASE-X comes in several different varieties.
  • It can be implemented over 4-pair Category 3, 4,
    or 5 UTP (100BASE-T).
  • It can also be implemented over 4-pair Category 5
    UTP or Shielded Twisted Pair (STP) (100BASE-TX),
    or as Ethernet over 2-strand fiber-optic cable

  • 1000BASE-T is Gigabit Ethernet.
  • This architecture supports data transfer rates of
    1 Gbps.

Token Ring
  • The Token Ring standards are defined in IEEE
  • A Token Ring network uses a token (that is, a
    special signal) to control access to the cable.
  • A token is initially generated when the first
    computer on the network comes online.
  • When a computer wants to transmit, it waits for
    and then takes control of the token when it comes
    its way.
  • The token can travel in either direction around
    the ring, but only in one direction at a time.

Fiber Distributed Data Interface (FDDI)
  • FDDI is a type of Token Ring network.
  • It runs on fiber-optic cable, and thus combines
    high-speed performance with the advantages of the
    token-passing ring topology.
  • It runs at 100 Mbps, and its topology is a dual
  • The outer ring is called the primary ring and the
    inner ring is called the secondary ring.

Networking Protocols and the OSI Model
OSI Model Overview
  • The Open Systems Interconnection (OSI) reference
    model is an industry standard framework that is
    used to divide the functions of networking into
    seven distinct layers.
  • Each layer provides specific services to the
    layers above and below it in order for the
    network to work effectively.

OSI Model Overview
  • A message begins at the top application layer and
    moves down the OSI layers to the bottom physical
  • As the message descends, each successive OSI
    model layer adds a header to it.
  • A header is layer-specific information that
    basically explains what functions the layer
    carried out.
  • Conversely, at the receiving end, headers are
    striped from the message as it travels up the
    corresponding layers.

What is a Protocol?
  • Protocol is a controlled sequence of messages
    that is exchanged between two or more systems to
    accomplish a given task.
  • Protocol specifications define this sequence
    together with the format or layout of the
    messages that are exchanged.

Transmission Control Protocol/Internet Protocol
  • The Transmission Control Protocol/Internet
    Protocol (TCP/IP) suite of protocols has become
    the dominant standard for inter-networking.
  • TCP/IP represents a set of public standards that
    specify how packets of information are exchanged
    between computers over one or more networks. 

Transmission Control Protocol/Internet Protocol
Internetwork Packet Exchange/Sequenced Packet
  • Internetwork Packet Exchange/Sequenced Packet
    Exchange (IPX/SPX) is the protocol suite employed
    originally by Novell.
  • It delivers functions similar to those included
    in TCP/IP.

  • NetBIOS Extended User Interface (NetBEUI) is a
    protocol used primarily on small Windows NT
  • NetBEUI is a simple protocol that lacks many of
    the features that enable protocol suites such as
    TCP/IP to be used on networks of almost any size.

  • AppleTalk is comprised of a e set of protocols
    that span the seven layers of the OSI reference
  • AppleTalk protocols were designed to run over the
    major LAN types, notably Ethernet and Token Ring,
    and also Apple's own LAN physical topology,

TCP/IP Utilities
  • TCP/IP is a complex collection of protocols.
  • Most vendors implement the suite to include a
    variety of utilities for viewing configuration
    information and troubleshooting problems.

  • Ping works by sending an ICMP echo request to the
    destination computer.
  • The receiving computer then sends back an ICMP
    echo reply message
  • It is also possible to use Ping to find the IP
    address of a host when the name is known.

  • Address Resolution Protocol (ARP) is the means by
    which networked computers map Internet Protocol
    (IP) addresses to physical hardware (MAC)
    addresses that are recognized in a local network.
  • Machines that do not know their IP addresses use
    Reverse Address Resolution Protocol (RARP).
  • It is used to obtain IP address information based
    on the physical or MAC address.

  • Nslookup returns the IP address for a given
  • It will also do the reverse and find the host
    name for a specified IP address.

  • The netstat command is used in Windows and
    UNIX/Linux to display TCP/IP connection and
    protocol information.
  • The netstat command provides a list of
    connections that are currently active.
  • Netstat statistics can be useful in
    troubleshooting TCP/IP connectivity problems.

  • The Microsoft TCP/IP stacks included in Windows
    operating systems provide the nbtstat utility,
    which is used to display NetBIOS information.

Ipconfig, winipcfg, config, and ifconfig
  • TCP/IP configuration information can be displayed
    using different utilities
  • Ipconfig Windows NT and Windows 2000
  • Winipcfg - Windows 95, 98, and ME (graphical
  • Ifconfig UNIX and Linux (command-line

Tracert, iptrace, and traceroute
  • It is often useful to trace the route a packet
    takes on its journey from source computer to
    destination host.
  • TCP/IP stacks include a route tracing utility
    that enables users to identify the routers
    through which the message passes.
  • The options depend on the operating system
  • Tracert
  • Iptrace
  • Traceroute

Connecting to the Internet
Synchronous and Asynchronous Serial lines
  • Synchronous serial transmission Data bits are
    sent together with a synchronizing clock pulse.
    Built-in timing mechanism coordinates the clocks
    of the sending and receiving devices.
  • Asynchronous serial transmission Data bits are
    sent without a synchronizing clock pulse. Uses a
    start bit at the beginning of each message. When
    the receiving device gets the start bit, it can
    synchronize its internal clock with the sender

  • The modem is an electronic device that is used
    for computer communications through telephone
  • It allows data transfer between one computer and
  • There are four main types of modems
  • Expansion cards
  • External modems
  • Built-in modems

Dial-Up Networking, Modem Standards, AT Commands
  • When computers use the public telephone system or
    network to communicate, it is called Dial-Up
    Networking (DUN).
  • All modems require software to control the
    communication session.
  • The set of commands that most modem software uses
    are known as the Hayes-compatible command set.
    The Hayes command set is based on a group of
    instructions that always begins with a set of
    attention characters (AT).

ISPs and Internet Backbone Providers
  • Services of an Internet Service Provider (ISP)
    are required to surf the Internet.
  • An ISP is a company that connects computers to
    the Internet and World Wide Web.
  • The actual connection to the Internet is tiered.
  • The ISP may link to a larger regional ISP, which
    in turn might connect to one of a number of
    nationwide computer centers.

ISPs and Internet Backbone Providers
  • The current U.S. Internet infrastructure consists
    of a commercial backbone and a high-speed service
    known as the Very High-Speed Backbone Network
    Service (vBNS).
  • The vBNS connects five supercomputer networks
    across the country
  • UUNET - a division of WorldCom
  • Cable Wireless USA
  • Sprint
  • ATT
  • BBN Planet

ISPs and Internet Backbone Providers
  • The ISP that cannot connect directly to the
    national backbone is charged a fee to connect to
    a regional provider that links to the national
    backbone through a Network Access Point (NAP).
  • Not all the Internet traffic goes through NAPs.
  • Some ISPs that are in the same geographic area
    make their own interconnections and peering

Digital Subscriber Line (DSL)
  • Digital Subscriber Line (DSL) is an always-on
    technology. This means there is no need to dial
    up each time to connect to the Internet.
  • DSL comes in several varieties
  • Asymmetric DSL (ADSL)
  • High Data Rate DSL (HDSL)
  • Symmetric DSL (SDSL)
  • Very High Data Rate DSL (VDSL)

Cable Modems
  • A cable modem acts like a LAN interface by
    connecting a computer to the Internet.
  • The cable modem connects a computer to the cable
    company network through the same coaxial cabling
    that feeds cable TV (CATV) signals to a
    television set.

Cable Modem versus DSL Internet Technologies
  • When it comes to comparing cable modem and DSL
    Internet technologies, both have their pros and

  • Another alternative to using analog telephones
    lines to establish a connection is ISDN.
  • Speed is one advantage ISDN has over telephone
    line connections.
  • ISDN uses a pair of 64Kbps digital lines to
    connect, which provides a total of 128Kbps
  • A telephone line connects at a maximum speed of
    56Kbps, and in some areas, doesnt even reach

  • Satellite is an option for users in rural areas
    or with no other access to high speed Internet
  • Satellite Internet does not require a phone line
    or cable. Two-way communication, for upload and
    download, is achieved with the use of a satellite
  • Download speed is up to 500 kbps while the upload
    speed is one-tenth of that of that.

Scope in Networking
  • All IT/ITES based companies require Networking
  • In software Industry also there are Networking
  • Not only IT companies need network all of them
    need network to reduce workload

Career Certifications
  • Microsoft Certifications
  • Cisco Certifications

Microsoft Certifications
M.C.P Microsoft Certified Professional M.C.S.A
- Microsoft Certified System Administrator (4
Papers) M.C.S.E - Microsoft Certified System
Engineer (7 papers)
Cisco Certifications
  • CCNA Cisco Certified Network Associate
  • CCNP Cisco certified Network Professional
  • CCIE Cisco Certified Internetwork Engineer

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