CCNA 1 Module 2

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CCNA 1 Module 2

• Networking Fundamentals

Never neglect the little things. Never skimp on
that extra effort, that additional few minutes,
that soft word of praise or thanks, that delivery
of the very best that you can do. It does not
matter what others think, it is of prime
importance, however, what you think about you.
You can never do your best, which should always
be your trademark, if you are cutting corners and
shirking responsibilities. You are special. Act
it. Never neglect the little things. - Og
Mandino
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CCNA 1 Module 2 Objectives

• By the end of this module you should be able to
• Explain the importance of bandwidth in networking
• Identify bps, kbps, Mbps, and Gbps as units of
  bandwidth
• Explain the difference between bandwidth and
  throughput
• Calculate data transfer rates
• Explain why layered models are used to describe
  data communication
• Explain the development of the OSI Model
• List the advantages of a layered approach
• Identify each of the seven layers of the OSI
  model
• Identify the four layers of the TCP/IP Model
• Describe the similarities and differences between
  the two models
• Identify the devices used in networking
• Understand the role of protocols in networking
• Define LAN, MAN, WAN, and SAN
• Explain VPNs and their advantages
• Describe the differences between internets and
  intranets

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Networking Devices

• Equipment connecting directly to a network
  segment is a device
• Two classifications of devices end-user and
  network devices
• End-user devices provide services directly to
  user - computers, printers, scanners
• Network devices provide data transport between
  end-user devices
• Networking devices
• Repeaters regenerate signals
• Hubs concentrate connections
• Bridges convert network transmission data
  formats as well as basic data transmission
  management
• Switches do not convert data transmission
  formats, but can transfer data only to the
  connection that needs the data
• Routers have all of the above listed
  capabilities, and can also connect to a WAN

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End-User and Network Device Icons
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Network Topology - Physical

• Physical topology includes the actual layout of
  the media
• Commonly used physical topologies
• Bus uses a single backbone cable terminated at
  both ends hosts directly connected directly to
  backbone
• Ring connects one host to the next and the last
  to the first, creating a physical ring of cable
  (series of Point-to-Point connections)
• Star connects all cables to a central point
• Extended star links individual stars together
  by connecting the hubs and/or switches
• Hierarchical similar to an extended star,
  however the system is linked to a computer that
  controls the traffic on the topology
• Mesh implemented to provide as much protection
  as possible from interruption of service
• Cellular Wireless topology

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Network Topologies - Physical
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Network Topologies - Logical

• Logical topology is how the hosts communicate
  across the medium
• Most common types of logical topologies are
  broadcast and token passing
• Broadcast topology means each host sends its data
  to all other hosts on the network medium. There
  is no order that the stations follow, it is first
  come first serve
• Token passing controls network access by passing
  an electronic token sequentially to each host.
  When a host receives a token, that host can send
  data on the network. If the host has no data to
  send, it passes the token to the next host and
  the process repeats itself. Examples are Token
  Ring and FDDI

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Network Protocols

• Protocols control all aspects of data
  communication including
• How the physical network is built
• How computers connect to the network
• How the data is formatted for transmission
• How data is sent
• How to deal with errors
• These rules are created and maintained by a
  variety of organizations, such as IEEE, ANSI,
  ITU, and EIA/TIA

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Local Area Networks (LANs)

• LAN components
• Computers
• Network Interface Cards
• Peripheral devices
• Networking media
• Network devices
• LANs make it possible for organizations to
  locally share files and printers efficiently
• Common LAN technologies
• Ethernet
• Token Ring
• FDDI

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Wide Area Networks (WANs)

• WANs interconnect LANs
• WANs provide
• Operate over a large geographically separated
  area
• Allow users to have real-time communication with
  other users
• Provide full-time remote resources connected to
  local services
• Provide e-mail, www, file transfer, and
  E-commerce services
• Common WAN technologies are
• Modems
• ISDN
• DSL
• Frame Relay
• T1, T3
• SONET

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Metropolitan Area Networks (MANs)

• A MAN is a network spanning a metropolitan area
• MANs consist of two or more LANs in a common
  geographic area
• Typically, a service provider connects two or
  more LAN sites using private communication lines
  or optical services
• MANs can use wireless bridging technology by
  beaming signals across public areas

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Storage Area Networks (SANs)

• SANs are dedicated, high-performance networks
  used to move data between servers and storage
  resources
• As a separate, dedicated network, it avoids
  traffic conflict between clients and servers
• SANs offer the following features
• Performance enable concurrent access to disk or
  tape arrays by two or more servers at high
  speeds, providing enhanced system performance.
• Availability have disaster tolerance built in,
  because data can be mirrored using a SAN up to 10
  km, or 6.2 m away.
• Scalability can use a variety of technologies,
  which allows for easy relocation of backup data,
  operations, file migration, and data replication.

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Virtual Private Network (VPN)

• VPNs offer secure, reliable connectivity over a
  shared public network infrastructure
• VPNs maintain the same security and management
  policies as a private network and are the most
  cost-effective method of establishing
  point-to-point connection between remote users
  and the enterprise network

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Types of VPNs

• Three types of VPNs
• Access VPNs provide remote access to a mobile
  worker and small office/home office (SOHO) to the
  headquarters of the Intranet or Extranet over a
  shared infrastructure. Use analog, dialup, ISDN,
  DSL, mobile IP, and cable technologies to
  securely connect mobile users, telecommuters, and
  branch offices
• Intranet VPNs link regional and remote offices
  to the headquarters of the internal network over
  a shared infrastructure using dedicated
  connections. Intranet VPNs differ from Extranet
  VPNs in that they allow access only to the
  employees of the enterprise.
• Extranet VPNs link business partners to the
  headquarters of the network over a shared
  infrastructure using dedicated connections.
  Extranet VPNs differ from Intranet VPNs is that
  they allow access to users outside the enterprise.

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Intranets and Extranets

• An Intranet web server differs from an Extranet
  web server in that the public must have the
  proper permissions and passwords to access the
  Intranet of an organization
• Intranets permit access by users who have access
  privileges to the internal LAN of the
  organization
• Extranets refer to applications and services that
  are Internet based, and use extended, secure
  access to external users or enterprises
• Extranets are the extension of two or more
  Intranets with a secure interaction between
  participant enterprises

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The Importance of Bandwidth

• Bandwidth is the amount of information that can
  flow through a network connection in a given
  period of time
• The following reasons are essential in studying
  bandwidth
• Bandwidth is finite the limited capacity of
  networks to carry information. Limiting factors
  are the laws of physics and the technologies used
  to place information on the media
• Bandwidth is not free it is possible to
  purchase LAN equipment to provides nearly
  unlimited bandwidth. WAN connection bandwidth is
  purchased from a service provider
• Bandwidth is a key factor in analyzing network
  performance, designing new networks, and
  understanding the Internet networking
  professionals must understand the impact of
  bandwidth and throughput on network performance
  and design.
• The demand for bandwidth is always increasing
  as soon as new network technologies and
  infrastructures are built to provide greater
  bandwidth, new applications are created to take
  advantage of this greater capacity

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Measurement of Bandwidth

• Basic unit of measurement of bandwidth in digital
  systems is bits per seconds (bps)
• Bandwidth is the measure of how much information,
  or bits, can flow from one place to another in a
  given amount of time, (second)
• Network bandwidth is described as
• thousands of bits/second (kbps)
• millions of bits/second (Mbps)
• billions of bits/second (Gbps)
• trillions of bits/second (Tbps)

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Bandwidth Limitations

• Bandwidth varies by media type and LAN and WAN
  technologies
• Physical differences in the way signals travel
  result in the fundamental limitations on the
  information-carrying capacity of a given medium
• Actual bandwidth of a network is determined by a
  combination of the physical media and the
  technologies chosen for signaling and detecting
  network signals

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Throughput

• Throughput is the 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
• Factors that determine throughput
• Internetworking devices
• Type of data being transferred
• Network topology
• Number of users on the network
• User computer
• Server computer
• Power conditions

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Digital vs Analog Bandwidth

• Analog bandwidth is how much the electromagnetic
  spectrum is occupied by each signal
• The basic unit of measurement in analog bandwidth
  is hertz (Hz), or cycles per second
• Measurement commonly seen in analog bandwidth are
  kilohertz (KHz), megahertz (MHz), and gigahertz
  (GHz). These units describe bandwidths of
  cordless phones, and wireless networks
• In digital signaling, all information is sent as
  bits, regardless of what kind of information it
  is.
• Voice, video and data all become streams of bits
  (Binary Stream) when they are prepared for
  transmission over digital media
• Regardless of how long it takes for the digital
  information to arrive at its destination and be
  reassembled, it can be viewed, listened to, read,
  or processed in its original form

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Layers in Data Communication

• For data packets to travel from a source to a
  destination, all of the devices must use the same
  language or protocol
• Data communications protocol is a set of rules or
  an agreements on the format and transmission of
  data
• Protocols in one layer performs a certain set of
  processes on data to prepares the data for
  transmission
• Data is passed to the next layer where another
  protocol performs a different set of operations
• Once the packet has been sent to the destination,
  the protocols undo the construction of the packet
  performed at source

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The OSI Model

• The OSI Model, released in 1984, is the
  descriptive network model created to standardize
  communication
• The OSI Model provides vendors with a set of
  standards to ensure greater compatibility
  interoperability
• The OSI Model has become the primary model for
  network communications, it is considered the best
  teaching tool for teaching people about sending
  and receiving data on the network

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OSI Layers

• The OSI Model is a framework thats used to
  understand how information travels through the
  network.
• There are seven numbered layers in the OSI Model
  that provide the following functions
• 1 Physical Layer Binary transmission
• 2 Data Link Layer Direct link control, access
  to the media
• 3 Network Layer Network address and best path
  determination
• 4 Transport Layer End-to-end communications
• 5 Session Layer Interhost communication
• 6 Presentation Layer Data representation
• 7 Application Layer Network processes to
  applications

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OSI Peer-to-Peer Communications

• For data to travel from source to destination,
  each source layer of the OSI Model must
  communicate with its destination peer layer
• Known as peer-to-peer communication.
• Each layers Protocols exchange information,
  called protocol data units (PDUs)
• Each Source layer communicates with a
  layer-specific PDU, hence its peer layer on the
  destination computer
• Layers depend on the service function of the
  layer below it.
• Lower layers use encapsulation to put the PDU of
  the upper layer into its data field then adds
  whatever headers and trailers the layer needs to
  perform its function
• The PDUs for the seven layers are as follows
• Layers 5, 6, 7 Data or information
• Layer 4 Segment
• Layer 3 Packet or datagram
• Layer 2 Frame
• Layer 1 Bits

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OSI Peer-to-Peer Communications
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The TCP/IP Model

• The historical and technical standard of the
  Internet is the TCP/IP model
• Created by the U.S. Department of Defense (DoD)
  to create a network that would survive any type
  of condition
• TCP/IP was developed as an open standard, meaning
  anyone was free to use TCP/IP
• Four TCP/IP Model layers are
• Application Layer
• Transport Layer
• Internet Layer
• Network Access Layer

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TCP/IP Model (Continued)

• Although some of the layers in the TCP/IP model
  have the same names as layers in the OSI model,
  there are some differences.
• The designers of the TCP/IP model felt the
  Application layer should include functions of the
  OSIs Session and Presentation layers. This
  Application layer handles data representation,
  encoding and dialog control.
• The Transport layer deals with the quality of
  service issues of reliability, flow control, and
  error correction.
• The Internet layer divides the TCP segments into
  packets and sends them from any network. The
  packets arrive at the destination network,
  independent of the path they took to get there.
• The Network Access layer is concerned with all of
  the components, both physical and logical, that
  are required to make a physical link. This layer
  includes all of the OSIs Physical and Data Link
  layer details.

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OSI and TCP/IP Model Similarities and Differences

• Similarities include
• Both have layers
• Both have Application layers, although they
  provide different services
• Both have comparable Transport and Network layers
• Both assume that packets are switched, meaning
  the packets take different paths to reach the
  same destination
• Differences include
• TCP/IP combines the OSI Presentation and Session
  layer into its Application layer
• TCP/IP combines the OSI Data Link and Physical
  layer into its Network Access layer
• TCP/IP appears to be simpler because it has fewer
  layers
• TCP/IP protocols are the standard around the
  development of the Internet, whereas the OSI
  model is used as a guide.

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The Encapsulation Process

• Five step conversion to encapsulate data
• Build the data alphanumeric characters are
  converted to data that can travel across the
  internetwork.
• Package the data for end-to-end transport by
  using segments, the transport function ensures
  that the message host at both ends can reliably
  communicate.
• Add the network IP address to the header data
  is put into a packet that contains the header and
  source and destination IP addresses.
• Add the data link layer header and trailer each
  network device must put the packet into a frame
• Convert to bits for transmission frame must be
  converted to 1s and 0s for transmission on the
  physical medium.

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Summary

• Today we discussed
• Data Encapsulation
• Layers, the OSI and TCP/IP Models
• Bandwidth
• Intranets Extranets
• VPNs, SANs, WANs, and LANs
• Networking Protocols
• Physical and Logical Topologies
• Network and User Devices

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Questions????
Hank Network Administrator (after finishing a
switch migration)