Topic 1 Networking today

• Every computer on a network is called a host or end device.
• Servers are computers that provide information to end devices.
• Some examples of servers are:

  • Email servers
  • Web servers
  • File servers
• Clients are computers that send requests to the servers to retrieve information. For example,

  • Requesting a web page from a web server
  • Requesting an email from an email server
  • Requesting a file from a file server
• One way for computers to be connected together is with a peer-to-peer network. This type of network design is only recommended for very small networks.
• Advantages of peer-to-peer network:

  • Easy to set up
  • Less complex
  • Lower cost
  • Used for simple tasks

  Disadvantages of peer-to-peer network:

  • No centralised administration
  • Not as secure
  • Not scalable
  • Slower performance
• An end device is where a message originates from or where it is received. Data originates from an end device, flows through a network and arrives at an end device.
• An intermediary device interconnects end devices. Some examples include:

  • Switches
  • Wireless access points
  • Routers
  • Firewalls
• Intermediary network devices also manages the data that flows through a network, for example:

  • Regenerate and re-transmit data signals
  • Maintain information about what pathways exist in the network
  • Notify other devices of errors and communication failures.
• Communication across a network is carried through a medium which allows a message to travel from source to destination. Some examples are:

  • Metal wires within cables - uses electrical impulses
  • Glass or plastic fibers - uses pulses of light
  • Wireless transmission - Uses modulation of specific frequencies of electromagnetic waves
• Network diagrams, often called topology diagrams, use symbols to represent devise within the network.
• Physical topology diagrams illustrate the physical location of intermediary devices and cable installation.
• Logical topology diagrams illustrate devices, ports, and the addressing scheme of the network.
• There are many different sizes of networks. For example,

  • Small Home Networks – connect a few computers to each other and the Internet
  • Small Office/Home Office – enables computer within a home or remote office to connect to a corporate network
  • Medium to Large Networks – many locations with hundreds or thousands of interconnected computers
  • World Wide Networks – connects hundreds of millions of computers world-wide – such as the internet
• Network infrastructures vary greatly in terms of

  • Size of area covered
  • Number of users connected
  • Number and types of services available
  • Area of responsibility
• Two most common types of networks are Local Area Networks (LAN) and Wide Area Networks (WAN).
• LANs:

  • Spans a small geographical area
  • Interconnect end devices in a limited area
  • Administered by a single organization or individual
  • Provide high-speed bandwidth to internal devices

  WANs:

  • Interconnect LANs over wide geographical areas
  • Typically administered by one or more service providers.
  • Typically provide slower speed links between LANs
• The internet is a worldwide collection of interconnected LANs and WANs where the LANs are connected to each other using WANs.
• The internet is not owned by any individual or group. The following groups were developed to help maintain structure on the internet:

  • The Internet Engineering Task Force (IETF)
  • The Internet Corporation for Assigned Names and Numbers (ICANN)
  • The Interactive Advertising Bureau (IAB)
• An intranet is a private collection of LANs and WANs internal to an organisation that is meant to be accessible only to the organisation's members or others who are authorised to do so.
• An organization might use an extranet to provide secure access to their network for individuals who work for a different organization that need access to their data on their network.
• Before converged networks, an organization would have been separately cabled for telephone, video, and data. Now, using a converged network, all of these services are provided over a single network.
• Network Architecture refers to the technologies that support the infrastructure that moves data across the network.
• There are four basic characteristics that the underlying architectures need to address to meet user expectations:

  • Fault tolerance
  • Scalability
  • Quality of Service (QoS)
  • Security
• A fault tolerant network limits the impact of a failure by limiting the number of affected devices. Multiple paths are required for fault tolerance.
• Reliable networks provide redundancy by implementing a packet switched network:

  • Packet switching splits traffic into packets that are routed over a network.
  • Each packet could theoretically take a different path to the destination.
• Implementing a packet switched network is not possible with circuit-switched networks which establish dedicated circuits.
• A scalable network can expand quickly and easily to support new users and applications without impacting the performance of services to existing users.
• Quality of Service (QoS) is the primary mechanism used to ensure reliable delivery of content for all users. With a QoS policy in place, the router can more easily manage the flow of data and voice traffic.
• There are two main types of network security that must be addressed:

  • Network infrastructure security
  • Physical security of network devices
  • Preventing unauthorized access to the devices
  • Information Security
  • Protection of the information or data transmitted over the network
• Three goals of network security (CIA):

  • Confidentiality – only intended recipients can read the data
  • Integrity – assurance that the data has not be altered with during transmission
  • Availability – assurance of timely and reliable access to data for authorized users
• Several new networking trends that effect organizations and consumers:

  • Bring Your Own Device (BYOD)
  • Online collaboration
  • Video communications
  • Cloud computing
• Bring Your Own Device (BYOD) allows users to use their own devices giving them more opportunities and greater flexibility, meaning end users have the freedom to access information and communicate using their own devices.
• Online collaboration allows end users to collaborate online. (Shocker)
• Video communication allows people to communicate using video
• Cloud computing allows us to store personal files or backup our data on servers over the internet which is made possible by data centres.
• There are 4 types of clouds:

  • Public Clouds
  • Available to the general public through a pay-per-use model or for free.
  • Private Clouds
  • Intended for a specific organization or entity such as the government.
  • Hybrid Clouds
  • Made up of two or more Cloud types – for example, part custom and part public.
  • Each part remains a distinctive object but both are connected using the same architecture.
  • Custom Clouds
  • Built to meet the needs of a specific industry, such as healthcare or media.
  • Can be private or public