Fundamentals of Computer Networks

Historical Foundations of Networking

  • ARPANET: An experimental system sponsored by the US Department of Defense (DoD) Advanced Research Projects Agency (ARPA), later known as DARPA, to network different types of computers.

  • Key Nodes: The first four nodes were located at UCLA, Stanford Research Institute (SRI), UCSB, and the University of Utah.

  • Significant Dates: The first node was installed at UCLA on September 2, 19691969, with the first transmission occurring on October 29, 19691969.

  • Pioneers: Professor Leonard Kleinrock, Vint Cerf, and Bob Kahn (creators of the TCP/IP protocol suite).

  • First Message: A failed attempt to send "LOG" resulted in only "LO" being transmitted between UCLA and SRI (352 miles352\,miles or 566 km566\,km apart) before the system crashed.

  • Philippine Internet: Established by Benjie Tan on March 29, 19941994, at 1:15 a.m.1:15\,a.m. via a Cisco 70007000 router at a PLDT center in Makati connected to SprintLink.

Communication Fundamentals

  • Elements of Communication: Message Source (Sender), Message Destination (Receiver), and Channel (Transmission Medium).

  • Network Components: Devices, Media, and Services.

  • End Devices: Interface between users and the network, such as computers, VoIP phones, and mobile handhelds.

  • Intermediary Devices: Connect end devices or multiple networks, including switches, wireless access points, routers, and firewalls.

  • Network Media: Metallic wires (electrical impulses), Glass/plastic fibers (light pulses), and Wireless (electromagnetic waves).

Network Infrastructures and Topologies

  • Topology Types:

    • Physical Topology: Identifies hardware locations and cable installations.

    • Logical Topology: Identifies devices, ports, and IP addressing schemes.

  • Network Configurations: Star (central switch), Extended Star, Full Mesh (high redundancy/cost), Partial Mesh, Hub and Spoke, and Hybrid.

  • Geographical Infrastructures:

    • PAN (Personal Area Network): Covers approximately 10 m10\,m.

    • LAN (Local Area Network): Limited area like buildings or campuses.

    • MAN (Metropolitan Area Network): City-wide area.

    • WAN (Wide Area Network): Large geographical areas like countries or continents, managed by TSPs or ISPs.

  • Specialized Types: WLAN (Wireless LAN), SAN (Storage Area Network), CAN (Campus Area Network), VPN (Virtual Private Network), and VLAN (Virtual LAN for broadcast domain division).

Network Hardware and Security Devices

  • Switch: Improves LAN efficiency using MAC addresses. Available as Modular or Fixed and Managed or Unmanaged.

  • Router: Directs traffic and provides network defense using Access Control Lists (ACLs).

  • Firewall: Filters traffic based on Whitelists or Blacklists to enforce security policies.

  • Modem: Modulator-demodulator converting digital and analog signals. Includes DSL, Cable, and Wireless types.

  • Wireless Access Point (WAP): Uses a Service Set Identifier (SSID) to authenticate and connect wireless devices to a wired network.