Computer Network Topology

• Computer Network


  Collection of computing devices that are interconnected so that it can communicate with each other
• Computer Network


  Combination of hardware and software that allow information and devices to be shared efficiently and economically
• Computer Network Sizes


  • Small networks (LANs)
  • Large geographical areas (WANs)
• Data


  Value that represents something
• Networks transmit data in order to share with others or for long-term storage
• The Mighty Bit


  Binary codes used to represent and interpret letters, numbers and special characters
• Byte


  Group of eight bits representing letters and numbers
• Getting Bits Moving


  Bits transmitted as signals over copper wire (electrical pulses), fiber-optic cable (light pulses), and wireless (radio waves)
• Network Building Blocks


  • Terminals
  • Workstations
  • Computers
  • Other devices (end nodes)
  • Transmission Media
  • Software to control Data Transmission
  • Network Devices
  • Network Architecture Standards
• Network Design Fundamentals


  • Scalability - ability of a network to be enlarged to accommodate growth
  • Availability - overall 'uptime' of the system
  • Security - Data must be protected against any unauthorized access
  • Manageability - Simplifying management of the system or network
• Network Topologies


  • Mesh
  • Star
  • Bus
  • Ring
• Bus Topology


  One long cable links all the devices in a network
• Bus Topology


  • A device wanting to communicate sends a broadcast message onto the wire that all other devices see, but only intended recipient actually accepts and processes the message
  • Each end of a bus network must be terminated with a resistor to keep the signal from bouncing back
• Ring Topology


  Each device has a dedicated point to point connection with only two devices on either side
• Ring Topology


  • All messages travel through a ring in the same direction
  • A failure in any cable or device breaks the loop and can take down the entire network
• Network Classifications


  • PANs - Personal Area Network/s
  • LANs - Local Area Network/s
  • MANs - Metropolitan Area Network/s
  • WANs - Wide Area Network/s
• PANs


  Devices communicate over the range of a person
• LANs


  Connects computers and peripherals over a limited range, have higher data transfer within LAN network
• LANs


  • Can be wired, wireless, or combination
  • Standard wired LAN uses Ethernet
  • Past used token ring protocols but now Ethernet using UTP is the norm
• LANs


  • Use Broadcast links to connect devices
  • Wireless LANs created using Wi-Fi (Wireless Fidelity) signal
  • Multiple LANs combined create a larger LAN - virtual LAN (VLAN)
• MANs


  Network that is utilize across multiple buildings or even city, much larger than the standard LAN but not as large as Wide Area Network (WAN)
• MANs


  • Communicating devices and provides the Internet connectivity for LANs in the metropolitan area
  • Commonly used in campus and large companies with multiple buildings
• WANs


  Collection of computers and networks spread over a large geographical area
• LANs (Local Area Network)

  • Use Broadcast links to connect devices
  • Wireless LANs created using Wi-Fi (Wireless Fidelity) signal
  • Multiple LANs combined that will create a larger LAN - virtual LAN (VLAN)
• MANs (Metropolitan Area Network)

  • Network that is utilize across multiple buildings or even city
  • Much larger than the standard LAN but not as large as Wide Area Network (WAN)
  • Communicating devices and provides the Internet connectivity for LANs in the metropolitan area
  • It commonly used in campus and large companies with multiple buildings
• WANs (Wide Area Network)


  • Collection of computers and network over geographic area
  • Covers broad area like districts and country
  • It is also called as Internet
• Network Transmission Technology


  • Point-to-Point Links
  • Broadcast Links
• Point-to-Point Links


  • Connection between individual pairs of machines - unshared connection
  • It also called as unicasting - connects between sender and receiver
  • Short messages called packets
  • If two machines are not directly connected to each other, packets may have to be forwarded by one or more intermediate machines
  • Multiple routes of different lengths are possible - routing algorithms plays an important role in point-to-point networks
• Broadcast Links


  • Communication channel is shared by all the machines on the network
  • Packets are sent by any machine and received by all the other machines - methods used 'One to many' transmission
  • Wireless network shared over a coverage region that depends on the wireless channel and the transmitting machine
  • If it is the intended destination, the packet is processed, otherwise, the packet is ignored
• Types of Computer Networks

  • Peer to Peer Networks
  • Server Based Networks
• Server


  Computer that shares it resources across the network
• Client


  Computer that access the server for the shared resources
• Peer-to-Peer Networks


  • Computer can take both a client and server role
  • Every user must also act as a network administrator and control access to the resources that reside on their machines and may grant unlimited access to users or no access to other users
  • Easy to install and configure - it is cheap to purchase and operate
• Peer-to-Peer Networks+


  • No additional equipment or software beyond a suitable operating system
  • No dedicated administrators are needed to run the network
  • It works best for networks under 10 users
• Peer-to-Peer Networks-

  • Increased workloads bog down machines when many users try to access the same resources
  • Hard to track data
  • Network security applies only to a single resources at a time
  • Each machine must be backed up individually to protect all shared data
• Server - Based Networks

  • It provides a centralized control over network resources by instituting network security and control through the server's own configuration and setup
  • It is high powered machines which are manufactured to handle multiple requests for shared resources expeditiously
• Server - Based Networks

  • High security - provides centralized verification of user accounts and passwords to guard access to the network
  • Password - users only need one single logon password to the network and not numerous ones for individuals resources
  • Network resources such as printers or scanners are more accessible as they are now fixed on specific servers and not spread around individual machines
  • Concentration of resources also makes data resources easier to back up and maintain
• Server-Based Networks+


  • Easier to scale up or scale down - making for adding new users or new devices easier
  • Simplified network administration for centralized user accounts, security and access controls
  • Single password for network logon delivers access to all resources
• Server-Based Networks-


  • In a worst case scenario, a server failure results in the lost of network resources
  • Complex, a special-purpose servers and software requires allocation of trained staff and specially designed facilities (server rooms) to house the servers resulting in increase costs
• Summary


  • Definition of Computer Network
  • Data transmission on the network
  • Building blocks of network
  • Network design fundamentals
  • Types of network topology
  • Network classifications definition and coverage range
  • Network Transmission Technology
  • Types of computer networks