Skip to main content

Introduction to LAN

Local Area Network(LAN)​

  • There are different topologies in networks. Some of the most prevalent network topologies are
    • Star topology
    • Bus topology
    • Ring topology

Star topology​

  • Individual devices are connected to a central networking device.
  • Characteristics of star topology are
    • Most common
    • Easy to add more devices
    • Expensive
    • More maintenance

Bus topology​

  • Devices are connected to a single connection called backbone cable.
  • Characteristics of bus topology
    • Cost efficient
    • Prone to becoming slow as all data travels through the single cable.
    • Difficult to troubleshoot.
    • If the backbone cable breaks, then the entire network will not work.

Ring topology​

  • Devices are connected in a circle to form a loop.
  • Each device is connected to two other devices.
  • Also called token topology.
  • The device will send it's own data before receiving and sending the data from nearby device.
  • Data travels in one direction only.
  • Characteristics of ring topology
    • Easy to troubleshoot.
    • Not efficient.
    • If the cable breaks anywhere then the entire network is down.

Switch​

  • Switches allow multiple devices such as computers, printers, etc to connect using ethernet cables into their port.
  • Switches keep track of what device is connected to which port and transmits data efficiently.

Routers​

  • Routers help in routing which is a process of connecting networks and passing data to them.
  • Switches and routers can be connected to each other to increase reliability.

Note: Switches connect individual devices and Routers connect networks.

Subnetting​

  • Subnetting is the process of splitting a large network into smaller networks.
  • Subnetting helps in assigning networks based on business needs.
    • For example: Grouping networks based on the deparments and decide the information and bandwidth for that network.
      • Engineering department
      • HR department
      • Accounting deparment
  • Subnets use IP address in 3 ways
    • Network address
      • Network address is the address of the start of the network.
      • For example: 192.168.1.0
    • Host address
      • Host address is the address of the device to be identified.
      • For example: 192.168.1.10
    • Default gateway
      • Default gateway is the special address of the device which is capable of sending data outside of the network.
      • This address is usually the first or last host address of the network.
      • For example: 192.168.1.1 or 192.168.1.255

Advantages of Subnetting​

  • Efficiency.
  • Security.
  • Full control over the network.

Address Resolution Protocol (ARP)​

  • ARP allows devices to identify themselves within the network.
  • ARP allows the device to associate it's IP address with it's MAC address on the network.
  • Initially a device sends an ARP Request to find the Mac address of the device with the IP address.
  • The device owning the IP address currently will send back an ARP Response with the MAC address.
  • This information will be stored in the ARP Cache of the requesting device for future reference.

Dynamic Host Configuration Protocol (DHCP)​

  • IP addresses can either be assigned manually or automatically and most commonly using DHCP.
  • The process of assigning and IP to the device is as below
    • DHCP Discover - Device sends a request to find any DHCP servers on the network.
    • DHCP Offer - DHCP server replies back with an IP address that the device can use.
    • DHCP Request - Device then sends a reply confirming to assign the IP address to it.
    • DHCP ACK - DHCP server sends an acknowledgement as confirmation.