Networking Fundamentals

1
Networking Fundamentals

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

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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

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Introduction to PC Networking
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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
  them.
• 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.

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Defining a Computer Network

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

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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
  users.

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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.

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Mail Services

• E-mail services work like the postal system, with
  one computer taking on the function of post
  office.
• 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.

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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.

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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
  transparently.
• In addition to their ease of use, they also make
  the network more flexible.

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The Internet

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

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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.

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Network Administration

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

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Simplex, Half-Duplex, and Full-Duplex
Transmission

• Simplex transmission is a single one-way baseband
  transmission.
• 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
  television.

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Simplex, Half-Duplex, and Full-Duplex
Transmission

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

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Simplex, Half-Duplex, and Full-Duplex
Transmission

• Traffic can travel in both directions at the same
  time.
• 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.

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Types of Networks
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Overview

• By using local-area network (LAN) and wide-area
  network (WAN) technologies, many computers are
  interconnected to provide services to their
  users.
• 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.

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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.

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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.

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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.

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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.

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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.

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Wide-Area Networks (WANs)

• The following are some of the more common WAN
  technologies
• 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)

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Wide-Area Networks (WANs)

• Connections across WAN lines may be temporary or
  permanent.
• 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.

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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.

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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.

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Adding a Network Interface Card (NIC)
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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.

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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

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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.

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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.

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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 cisco.com 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
  table.

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Physical Components of a Network
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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.

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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.

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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.

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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
  governments.
• Implementing the mesh topology is expensive and
  difficult.

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Physical versus Logical Topology

• Networks have both a physical and logical
  topology
• Physical topology the layout of the devices and
  media.
• 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.

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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
  means).
• 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
  distribution).

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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).

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Networking Media

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

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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.

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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.

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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.

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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.

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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
  networks.

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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.

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LAN Architectures
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Ethernet

• 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
  media.

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Ethernet

• 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.

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Ethernet

• 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
  (100BASE-FX).

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Ethernet

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

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Token Ring

• The Token Ring standards are defined in IEEE
  802.5.
• 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.

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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
  ring.
• The outer ring is called the primary ring and the
  inner ring is called the secondary ring.

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Networking Protocols and the OSI Model
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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.

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OSI Model Overview

• A message begins at the top application layer and
  moves down the OSI layers to the bottom physical
  layer.
• 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.

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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.

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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. 

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Transmission Control Protocol/Internet Protocol
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Internetwork Packet Exchange/Sequenced Packet
Exchange

• 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.

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NetBEUI

• NetBIOS Extended User Interface (NetBEUI) is a
  protocol used primarily on small Windows NT
  networks.
• 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.

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AppleTalk

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

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TCP/IP Utilities
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Overview

• 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.

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Ping

• 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.

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ARP, RARP, NSLOOKUP

• 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.

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ARP, RARP, NSLOOKUP

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

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Netstat/tpcon

• 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.

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Nbtstat

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

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Ipconfig, winipcfg, config, and ifconfig

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

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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

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Connecting to the Internet
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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
  clock.

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Modems

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

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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).

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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.

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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

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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
  agreements.

81
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)

82
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.

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Cable Modem versus DSL Internet Technologies

• When it comes to comparing cable modem and DSL
  Internet technologies, both have their pros and
  cons.

84
ISDN

• 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
  throughput.
• A telephone line connects at a maximum speed of
  56Kbps, and in some areas, doesnt even reach
  that.

85
Satellite

• Satellite is an option for users in rural areas
  or with no other access to high speed Internet
  service.
• 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
  dish.
• Download speed is up to 500 kbps while the upload
  speed is one-tenth of that of that.

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Scope in Networking

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

87
Career Certifications

• Microsoft Certifications
• Cisco Certifications

88
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)
89
Cisco Certifications

• CCNA Cisco Certified Network Associate
• CCNP Cisco certified Network Professional
• CCIE Cisco Certified Internetwork Engineer

CCIE
90
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