Common Network Devices | IGCSE Information and Communication Technology Preparation - Year 11 PDF Download

Network Interface Cards (NICs)

• Network Interface Cards (NIC): Network Interface Cards enable electronic devices to connect to networks. They are typically linked to the motherboard, although in modern setups, they are often integrated.
• Unique Identifiers: Every network interface card possesses a distinct identifier called a MAC address, which is established during the manufacturing phase.
• Wireless Network Interface Cards (WNIC): WNICs function similarly to NICs, but they utilize wireless connections to link devices to networks.

MAC Addresses

• A MAC address, also known as Media Access Control address, is a unique identifier assigned to a network interface controller for use as a network address in communications within a network segment.
• It is a 48-bit code expressed in 12 hexadecimal characters grouped in pairs.
• The general format of a MAC address involves separating each pair of hexadecimal digits with a hyphen ("-").
• Example of a MAC Address
  • For instance, let's consider Microsoft's Organizationally Unique Identifier (OUI) of "00-15-5D." A freshly manufactured laptop from Microsoft could bear a MAC address like "00-15-5D-45-1B-3F."

Hubs

• Hubs serve as devices enabling multiple other devices to connect to them.

• Hubs vs. Switches: Hubs are more economical than switches but have limitations:
  • When a hub receives data, it broadcasts it to all devices on the network.
  • This broadcasting leads to unnecessary traffic, especially in large networks.
  • Security concerns arise as every device receives the data packet.
• Hub Functionality
  • When a hub gets a data packet, it disseminates it to every device on the network.
  • This process can create congestion and compromise network security.

Switches

• Switches are networking devices that connect multiple devices together, sending data packets only to their intended destination, unlike hubs.
• Switches operate based on MAC addresses, utilizing lookup tables to forward data efficiently to the correct port.
• When a switch receives a data packet, it inspects the destination MAC address and forwards the packet accordingly.

• This is done by each switch having a lookup table:

• When a switch receives a data packet, it checks the destination MAC address and searches for that address in its lookup table.
• After finding the matching MAC address, the switch forwards the data packet to the appropriate port.

Bridges

• Bridges are used to link two networks or network segments, forming a single, larger network.
• It is important to note that, unlike routers, bridges cannot communicate with external networks such as the internet.