CCNA 1 v 3.1 Module 2

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CCNA 1 v 3.1Module 2

• Networking Fundamentals
• September 2004

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2.1.1 Types of Networks

• PAN- Personal Area Network
• LAN Local Area Network
• MAN Metropolitan Area Network
• WAN Wide Area Network
• SAN Storage Area Network

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2.1.2 Bulletin Boards

• A central communication in a dialup connection
• Users may leave or reply to messages
• Users may upload or download

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Bulletin Board Problems

• Very little direct communication
• Limited to the people who know the address
• One modem one connection
• Hard to keep up with growing demand

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2.1.3 Types of Devices

• A device is any equipment that connects to a
  network segment
• End user devices - computers, printers, scanners
• Network devices allow end users to communicate
• Hosts - End user devices

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Specific Devices

• NIC cards Network Interface Cards
• PCMCIA - Personal Computer Memory Card
  International Association NIC for a laptop
• Repeater - A network device used to regenerate a
  signal.
• Hubs - Hubs concentrate connections. They take a
  group of hosts and allow the network to see them
  as a single unit.

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Devices (Cont)

• Bridges - Bridges provide connections
  between LANs.
• Switches - determine if data should remain on a
  LAN and transfer data only to the connection that
  needs it.
• Routers - Connect to a WAN, which allows them to
  connect LANs that are separated by great
  distances.

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2.1.4 Topologies

• Physical Topology The actual layout of the wire
  or media.
• Logical Topology defines how the media is
  accessed by the hosts for sending data

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Physical Topologies

• Bus Topology - Uses a single backbone cable that
  is terminated at both ends. All the hosts connect
  directly to this backbone.
• Ring Topology - Connects one host to the next and
  the last host to the first. This creates a
  physical ring of cable.

Bus
Ring
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• Star Topology - Connects all cables to a central
  point.
• Extended Star Topology - Links individual stars
  together by connecting the hubs or switches.

Extended Star
Star
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• Hierarchical topology The system is linked to a
  computer that controls the traffic on the
  topology.
• Mesh topology - Implemented to provide as much
  protection as possible from interruption of
  service. Every device is connected to each
  other.

Hierarchical
Mesh
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Logical Topologies

• Broadcast Topology
• Ethernet
• Token Passing Topology
• Token Ring
• FDDI (Fiber Distributed Data Interface)
• Arcnet is token passing on a bus topology

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2.1.5 Protocols Control Data

• How the physical network is built
• How computers connect to the network
• How the data is formatted for transmission
• How that data is sent
• How to deal with errors

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Network Organizations

• IEEE - Institute of Electrical and Electronic
  Engineers
• ANSI - American National Standards Institute
• TIA - Telecommunications Industry Association
• EIA - Electronic Industries Alliance
• ITU - International Telecommunications Union
  formerly known as the (CCITT). Comité Consultatif
  International Téléphonique et Télégraphique

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2.1.6 LANs designed for

• Operate within a limited geographic area
• Allow multi-access to high-bandwidth media
• Control the network privately under local
  administrator
• Provide full-time connectivity to local services
• Connect physically adjacent devices

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LAN technologies

• Ethernet
• Token Ring
• FDDI

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LAN Devices

• Hub
• Router
• Ethernet Switch
• Bridge
• Repeater

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2.1.7 WANs Designed for

• Operate over a large geographical area
• Allow access over serial interfaces operating at
  lower speeds
• Provide full-time and part-time connectivity
• Connect devices separated over wide, even global
  areas
• Provide e-mail, Internet, file transfer, and
  e-commerce services

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WAN Technologies

• Modems
• Integrated Services Digital Network (ISDN)
• Digital subscriber line (DSL)
• Frame Relay
• T1, E1, E3, and T3
• Synchronous Optical Network (SONET)

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2.1.8/9 MANs and SANs

• A MAN is a network that spans a metropolitan area
  such as a city or suburban area.
• A SAN is a dedicated, high-performance network
  used to move data between servers and storage
  resources.

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Features of a SAN

• 1. Performance SANs enable concurrent access
  of disk or tape arrays by two or more servers at
  high speeds, providing enhanced system
  performance.
• 2. Availability SANs have disaster tolerance
  built in, because data can be mirrored using a
  SAN up to 10 kilometers (km) or 6.2 miles away.
• 3. Scalability Like a LAN/WAN, it can use a
  variety of technologies. This allows easy
  relocation of backup data, operations, file
  migration, and data replication between systems.

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2.1.10 VPNs

• Virtual Private Network
• A VPN is a private network that is constructed
  within a public network infrastructure such as
  the global Internet.
• Using VPN, a telecommuter can remotely access the
  network of the company headquarters.

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2.1.11 Types of VPNs

• 1. Access VPNs Communication between a mobile
  worker or small office to the main office
• 2. Intranet VPNs - Regional or remote office
  connection over a dedicated line. Only users in
  that business can use it.
• 3. Extranet VPNs - Regional or remote office
  connection over a dedicated line. Anyone can use
  it.

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2.1.12 Intranets and Extranets

• Intranet - A network primarily for the usage
  within an enterprise
• Extranets - Usage of two or more Intranets with
  passwords.

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2.2.1 Bandwidth

• The amount of information that can flow through a
  network connection in a given period of time.
• Bandwidth is finite.
• Bandwidth is not free.
• Bandwidth is a key factor in analyzing
  performance.
• The demand for Bandwidth is increasing.

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2.2.3 Bandwidth vs Speed

• Bandwidth is the measure of how much data can
  flow
• Speed is the rate it does flow.

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Measurements of Bandwidth

• bps (bits per second)
• kbps (kilobits per second)
• Mbps (megabits per second)
• Gbps (Gigabits per second)
• Tbps (Terabits per second)

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2.2.4 What can effect bandwidth?

• Network technologies
• Media
• Signaling methods

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2.2.5/6 Throughput

• Throughput refers to actual measured bandwidth,
  at a specific time of day, using specific
  Internet routes, and while a specific set of data
  is transmitted on the network.
• The smallest cable bandwidth is the maximum
  possible throughput

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Factors that effect throughput

• Internetworking devices
• Type of data being transferred
• Network topology
• Number of users on the network.
• Users Computer
• Server computer
• Power conditions
• Congestion

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2.2.7 Analog vs Digital

• Analog bandwidth is measured by how much of the
  electromagnetic spectrum is occupied by each
  signal.
• Since all digital information is sent in bits,
  the bandwidth of the medium is the digital
  bandwidth.
• Digital bandwidth is always available no matter
  how small, with analog bandwidth there may not be
  bandwidth available because something else is
  using it.

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2.3.2 Need for Protocols

• The peer layers must speak the same language.
• Each company was using its own guidelines to
  exchange information.
• Companies were developing their own network
  technologies and therefore could not communicate
  with each others networks.

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2.3.3 Benefits of the OSI Model

• Reduces complexity
• Standardizes interfaces
• Facilitates modular engineering
• Ensures interoperable technology
• Accelerates evolution
• Simplifies teaching and learning

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2.3.4 OSI Model

• 7. Application
• 6. Presentation
• 5. Session
• 4. Transport
• 3. Network
• 2. Data Link
• 1. Physical

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Physical Layer
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Data Link Layer
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Network Layer

• Provides connectivity and path selection between
  two host
• Provides Logical address
• No error correction, best effort delivery.

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Transport Layer
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Session Layer
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Presentation Layer
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Application Layer
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2.3.5 Peer-to-Peer

• Peer-to-peer Each layer of the OSI model at the
  source must communicate with its peer layer at
  the destination.
• The protocols of each layer exchange information,
  called protocol data units (PDUs).

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PDUs
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Data Link Layer for Example

• The data link layer provides a service to the
  network layer.
• It encapsulates the network layer information in
  a frame (the Layer 2 PDU).
• The frame header contains information (for
  example, physical addresses) required to complete
  the data link functions.
• The data link layer provides a service to the
  network layer by encapsulating the network layer
  information in a frame.

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2.3.6 TCP/IP Model
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Compare the two models
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Similarities include

• Both have layers.
• Both have application layers, though they include
  very different services.
• Both have comparable transport and network
  layers.
• Both models need to be known by networking
  professionals.

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Similarities Continued

• Both assume packets are switched. This means that
  individual packets may take different paths to
  reach the same destination.
• This is contrasted with circuit-switched networks
  where all the packets take the same path.

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Differences

• TCP/IP combines the presentation and session
  layer issues into its application layer.
• TCP/IP combines the OSI data link and physical
  layers into the network access layer.
• TCP/IP appears simpler because it has fewer
  layers.

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Differences Continued

• TCP/IP protocols are the standards around which
  the Internet developed, so the TCP/IP model gains
  credibility just because of its protocols. In
  contrast, networks are not usually built on the
  OSI protocol, even though the OSI model is used
  as a guide.

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A closer look at TCP/IP Application Layer

• The application layer has different functions in
  each model.
• The application layer handles issues of
  representation, encoding, and dialog control.

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Transport Layer

• The transport layer deals with the quality of
  service issues of reliability, flow control, and
  error correction.
• TCP (transmission control protocol) provides
  excellent and flexible ways to create reliable,
  well-flowing, low-error network communications.

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Network Access Layer

• Known as the host-to-network layer.
• This layer is concerned with all of the
  components, both physical and logical, that are
  required to make a physical link.
• It includes the networking technology details,
  including all the details in the OSI physical and
  data link layers.

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TCP/IP Protocols
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5 Steps for Encapsulation

• 1. Build the data As a user sends an e-mail
  message, its alphanumeric characters are
  converted to data that can travel across the
  internetwork.
• 2. Package the data for end-to-end transport
  The data is packaged for internetwork transport.
  By using segments, the transport function ensures
  that the message hosts at both ends of the e-mail
  system can reliably communicate.

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Step 3

• 3. Add the network IP address to the header The
  data is put into a packet or datagram that
  contains a packet header with source and
  destination logical addresses. These addresses
  help network devices send the packets across the
  network along a chosen path.

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Step 4

• 4. Add the data link layer header and trailer
  Each network device must put the packet into a
  frame. The frame allows connection to the next
  directly-connected network device on the link.
  Each device in the chosen network path requires
  framing in order for it to connect to the next
  device.

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Step 5

• 5. Convert to bits for transmission The frame
  must be converted into a pattern of 1s and 0s
  (bits) for transmission on the medium. A clocking
  function enables the devices to distinguish these
  bits as they travel across the medium. The medium
  on the physical internetwork can vary along the
  path used. For example, the e-mail message can
  originate on a LAN, cross a campus backbone, and
  go out a WAN link until it reaches its
  destination on another remote LAN.

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Receiving vs Sending