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Chapter1

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  • This chapter introduces the platform of data networks upon which social and business relationships increasingly depend. The material lays the groundwork for exploring the services, technologies, and issues encountered by network professionals as they design, build, and maintain the modern network.
  • Instant messaging is everywhere and can include audio and video conversations. IM can send text messages to mobile phones.
  • The above figure shows some of the most common intermediate devices used to direct and manage messages across the network.
  • The cost to create many alternate paths with enough capacity to support a large number of simultaneous circuits, and the technologies necessary to dynamically recreate dropped circuits in the event of a failure, led the Department of Defense (DoD) to consider other types of networks.
  • In the search for a network that could withstand the loss of a significant amount of its transmission and switching facilities, the early Internet designers reevaluated early research regarding packet switched networks. The DoD researchers realized that a packet switched connectionless network had the features necessary to support a resilient, fault tolerant network architecture. The need for a single, reserved circuit from end-to-end does not exist in a packet switched network. The problem of underutilized or idle circuits is eliminated -- all available resources can be used at any time to deliver packets to their final destination. By providing a method to dynamically use redundant paths, without intervention by the user, the Internet has become a fault tolerant, scalable method of communications.
  • There are two types of network security concerns that must be addressed to prevent serious consequences – network infrastructure security and content security.
  • DoS- a type of attack on a network that is designed to bring the network to its knees by flooding it with useless traffic.
  • Transcript

    • 1. Ch 1 - Chapter 1 Living in a Network-Centric World
    • 2. Objectives
      • Describe how networks impact our daily lives
      • Describe the role of data networking in the human network
      • Identify the key components of any data network
      • Identify the opportunities and challenges posed by converged networks
      • Describe the characteristics of network architectures relating to fault tolerance, scalability, quality of service (QoS) and security
      Ch 1 -
    • 3. Networks Supporting The Way We Live
      • Data networks that were once the transport of information for businesses are now also used to improve our quality of life
        • check bank balance and pay bills electronically
        • find the least-congested route to a destination
        • use instant messaging and chat for both personal and business use
        • post and share your photographs, home videos and experiences
        • shop and sell at online auctions
        • use Internet phone services
      Ch 1 -
        • obtain health information and nutritional advice
    • 4. Today’s Popular Communication Tools
      • Instant messaging (IM)
        • real-time text communication between two or more users
        • also supports voice, photo and video sharing, and file transfers
      • Blogs or weblogs
        • individuals publish their personal opinions and thoughts about any conceivable topic
        • allow unfiltered and unedited publication of ideas from anyone
      • Podcasting
        • website that contains audio files available for downloading
      • Wikis
        • publicly created web content that groups of people can edit and view together
        • organizations and individuals build their own wikis to capture collected knowledge for use as collaboration tools
      Ch 1 -
    • 5. Examples of Communication Tools Ch 1 -
    • 6. Networks Supporting The Way We Learn
      • Traditional learning methods make use of textbooks and instructor-led classes
      • Courses delivered using networks or Internet resources are often called online learning experiences or e-learning
      • Online courses can contain voice, data and video
        • available to the students at any time from any place
      • Blended courses can combine instructor-led classes with online courseware to provide the best of both delivery methods
      Ch 1 -
    • 7. Global Online Learning Experience
      • The instructor provides a syllabus and establishes a preliminary schedule for completing the course content
      • The way we learn is supported by courseware delivered over the data network
      Ch 1 -
    • 8. Learning by Sharing and Exploring
      • Students can communicate with the instructor and fellow students using online tools
        • bulletin/discussion boards, chat rooms and instant messaging
      • Links provide access to learning resources outside the courseware
      Ch 1 -
    • 9. Online Courseware Administration
      • Improved management and administration of courses
        • enrollment, assessment delivery and grade books
      Ch 1 -
    • 10. Benefits of Online Courseware
      • Current and accurate training materials
        • collaboration among vendors, equipment manufacturers and training providers ensures that the courseware is up to date with the latest processes and procedures
      • Availability of training to a wide audience
        • online training is not dependent on travel schedules, instructor availability, or physical class size
      • Consistent quality of instruction
        • quality of instruction does not vary as it would if different instructors were delivering an in-person lesson
      • Cost reduction
        • facilities to support in-person training can be reduced or eliminated
      Ch 1 -
    • 11. Networks Supporting The Way We Work
      • Business applications can be accessed remotely as if employees were on site
      • Workers in any location can reach each other and access multiple resources on the network
      Ch 1 - Remote Access Accessing Multiple Resources
    • 12. Networks Supporting The Way We Play
      • Explore places of interest interactively or preview actual destinations before a trip
      • Posting photographs about an event online for others to view
      • Participate in online games
      • Preview motion pictures
      Ch 1 -
    • 13. Basic Characteristics of Communication
      • Rules or agreements to govern the conversation are first established
        • these rules, called protocols, must be followed in order for the message to be successfully delivered and understood
      • A message with important information may need a confirmation that the message has been received and understood
      • As a message moves through the network, many factors can prevent the message from reaching the recipient or distort its intended meaning
        • internal or external factors
      Ch 1 -
    • 14. External Factors
      • The quality of the pathway between the sender and the recipient
      • The number of times the message has to change form
      • The number of times the message has to be redirected or readdressed
      • The number of other messages being transmitted simultaneously on the communication network
      • The amount of time allocated for successful communication
      Ch 1 -
    • 15. Internal Factors
      • The size of the message
        • it is more difficult to deliver a large bulky message, quickly and without damage, than it is to deliver a number of smaller, less complex messages
      • The complexity of the message
      • The importance of the message
      Ch 1 -
    • 16. Four Elements of a Network
      • Rules or agreements to govern the messages are sent, directed, received and interpreted
      • The messages or units of information that travel from one device to another
      • A means of interconnecting these devices – a medium that can transport the messages from one device to another
      • Devices on the network that exchange messages with each other
      Ch 1 -
    • 17. Rules
      • Rules govern every step of the process, from the way cables are designed to the way the digital signals are sent
      • These rules are called protocols, e.g. TCP/IP protocol stack
      Ch 1 -
    • 18. Messages
      • Message is a generic term that encompasses text, voice or video information
      • The message must be converted to bits , binary coded digital signals, before they are transmitted on the medium
      Ch 1 -
    • 19. Medium
      • Physically carries the message
      • Connects the devices
      • Can be wired or wireless
      Ch 1 - Wired connections Wireless connections UTP cables wireless router
    • 20. Devices
      • End-user devices
        • desktop computer
        • server
        • notebook (or laptop)
        • IP phone
      • Networking devices
        • LAN switch
        • firewall
        • router
        • wireless router
      Ch 1 -
    • 21. Common Data Network Symbols Ch 1 -
    • 22. Non-Converged Networks
      • In the past, every one of the services required a different technology to carry its particular communication signal
      • Each service has its own set of rules and standards
      Ch 1 -
    • 23. Converged Networks
      • Convergence occurs when telephones, broadcasts (radio and TV), and computer communications all use the same rules, devices and media to transport messages
      Ch 1 -
    • 24. Network Architecture
      • Refers to the conceptual plans on which a physical network is built
      • Must support a wide range of applications and services
      • Four basic characteristics of the network architecture
        • fault tolerance
        • scalability
        • quality of service
        • security
      Ch 1 -
    • 25. Fault Tolerance
      • A fault tolerant network limits the impact of hardware or software failure
        • recover quickly when a failure occurs
        • depend on redundant links, or paths, between the source and destination of a message
        • redundant connections allow for alternate paths
      Ch 1 -
    • 26. Circuit Switched Connection-Oriented Networks
      • A physical, dedicated path or circuit is temporary setup between the source and destination
      • The circuit is maintained for the duration of the call
      • Early circuit-switched networks do not dynamically recover from drop circuits
      Ch 1 -
    • 27. Packet Switched Connectionless Networks
      • The entire message is broken into packets which are addressed and numbered
      • Any packets can be sent through the network using any available path
      Ch 1 -
    • 28. Scalability
      • A scalable network can expand quickly to support new users and applications without impacting the performance of the service being delivered to existing users
      • Depends on a hierarchical layered design for the physical infrastructure and logical architecture
      Ch 1 -
    • 29. Internet Structure
      • The Internet is a hierarchical structure of interconnected networks
      • Many individual networks that provide Internet connectivity cooperate to follow accepted standards and protocols
        • new products can integrate with and enhance the existing infrastructure
      Ch 1 -
    • 30. Quality of Service (QoS)
      • QoS refers to the mechanism that manage congested network traffic
      • Congestion is caused when the demand on the network exceeds the available capacity
      • Some constraints on network resources cannot be avoided
      Ch 1 -
        • technology limitations
        • cost
        • local availability of high-bandwidth services
    • 31. QoS Classification
      • Prioritize which types of data packets must be delivered at the expense of other types of packets that can be delayed or dropped
        • use queues to prioritize traffic
      • Classify applications in categories based on specific quality of service requirements
      Ch 1 -
    • 32. Prioritizing Network Traffic
      • Delay-sensitive (or time sensitive) communication
        • increase priority for services like voice or video transmission
      • Delay-insensitive (or non-time sensitive) communication
        • decrease priority for web page retrieval or e-mail
      • High importance to organization
        • increase priority for business transaction data or production control
      • Undesirable communication
        • decrease priority or block unwanted activity such as gaming
      Ch 1 -
    • 33. Security
      • The Internet has become a widely accessible means of business and personal communications
        • the same environment that attracts legitimate business, however, also attracts scam artists and vandals
      • Compromising the integrity of company assets could lead to serious business and financial repercussions
      Ch 1 -
      • Tools and procedures are being implemented to combat inherent security flaws in the network architecture
    • 34. Network Security Concerns
      • Network infrastructure security
        • physical securing of devices that provide network connectivity and preventing unauthorized access to the management software that resides on them
      • Content security
        • protecting the information contained within the packets being transmitted over the network and the information stored on network attached devices
        • tools to provide security for the content of individual messages must be implemented on top of the underlying protocols
      Ch 1 -
    • 35. Consequences of Security Breach
      • Network outage causing a loss of communications and transactions occurring, with consequent loss of business
      • Misdirection and loss of personal or business funds
      • Theft of intellectual property such as project bids and strategic plans and used by a competitor
      • Exposure of confidential customer data, which may result in loss of market confidence in the business
      Ch 1 -
    • 36. Security Measures
      • Prevent unauthorized disclosure or theft of information
        • ensure confidentiality
      • Prevent unauthorized modification of information
        • maintain communication integrity
      • Prevent denial of service (DoS)
        • ensure availability
        • DoS – attack on the network that flooding it with useless traffic
      Ch 1 -
    • 37. Confidentiality, Integrity and Availability
      • Ensuring confidentiality
        • allowing only the intended and authorized users to read the data
        • a strong system for user authentication
        • encrypting the content
      • Maintaining communication integrity
        • data integrity is the assurance that the information has not been altered in transmission, from source to destination
        • source integrity is the assurance that the identity of the sender has been validated
        • using digital signatures and hashing algorithms
      • Ensuring availability
        • resources are available to authorized users
        • virus software and firewalls are used to combat virus and DoS attacks
        • building fully redundant network infrastructures
      Ch 1 -
    • 38. Trends in Networking
      • Increasing number of mobile users
        • a demand for more mobile connectivity to data networks
      • New and more capable devices
        • functions performed by cell phones, personal digital assistants, organizers and pagers are converging into single handheld devices with continuous connectivity to providers of services and content
      • Increased availability of services
      Ch 1 -
        • new services are introduced and older services are enhanced to meet user demands

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