Network Hardware - Cambridge (CIE) IGCSE ICT Revision Notes 2021

Routers

• Definition: A router is responsible for routing data packets between different networks.
• Functionality:
  • Connects Local Area Networks (LAN) to the wider internet (WAN).
  • Manages and prioritizes data traffic to maintain connections' stability.
  • Assigns IP addresses to devices on the network.
  • Example: Directing internet traffic to devices within a home network.

Data Packets

• Components:
  • Header: Contains source and destination IP addresses, packet number, and error checks.
  • Payload: The actual data being transported.
  • Trailer: May contain additional security information and end of packet notification.

IP Addresses

• Definition: Unique identifiers for devices communicating over the Internet (WAN).
• Types:
  • IPv4: Comprises 4 blocks of numbers, total of 32 bits.
    • Provides over 4 billion unique addresses.
  • IPv6: Comprises 8 blocks of hexadecimal digits, total of 128 bits.
    • Provides over one billion unique addresses per person globally.

Network Interface Card (NIC)

• Purpose: Essential for connecting a computer to a network.
• Types: Can be wired or wireless.

Hubs

• Function: Connects multiple devices in a network.
• Characteristic: Sends all data received to all connected devices, leading to potential inefficiencies and security issues.

Switches

• Function: Connects multiple devices on a network but only sends data to the intended device.
• Efficiency: Uses a lookup table to forward data based on MAC addresses.

MAC Addresses

• Definition: Unique identifiers for devices communicating over a local area network (LAN).
• Characteristics:
  • Static and do not change.
  • 12 hexadecimal digits (48 bits), usually grouped in pairs.

Bridges

• Function: Connects two local area networks (LANs) to form a larger network.
• Characteristic: Different from switches and hubs as they only connect LANs.

Worked Example

• Difference between a switch and a hub:
  • Switch: Forwards data packets based on destination MAC address.
  • Hub: Broadcasts incoming packets to all connected devices.