Network devices (A2.1 Network fundamentals)

Firewall

Monitors and controls incoming and outgoing network traffic (data = packets) based on predetermined security rules

• Barrier between trusted internal network and untrusted external networks

• Goal: block malicious traffic, prevent unauthorized access

• Types:

  • Hardware firewall - physical network security device  

    • Comprehensive protection at network perimeter for entire network

  • Software firewall - application installed on individual device

    • ^detailed control over individual device activities

Network interface card (NIC)

• Facilitates interface between physical network and device’s processing capabilities

• Each has unique media access control (MAC) address - identifies device on local network

  • Ensure data packets delivered to correct hardware destination

• Types:

  • Ethernet- usually for LAN

  • Fibre-optic - fast

  • Wireless - wireless connectivity

Gateway

Bridges two networks that use disparate protocols

• Used when need to translate data to different format or different networking tech need to interact

• Can incorporate: security functions, filtering, traffic management

  • =^data flow and security across networks

• Ex: enable communication between office network and internet, converting private network addresses to public address using protocols like NAT (network address translation)

Modem (modulator-demodulator)

Bridges digital data networks and analogue phone systems

• Usually: Provide internet in residential/business areas by interfacing with service provider’s network (standard telephone lines, cable, satellite connections)

• Ex: cable modem converts digital signals from router to analogue signals to transmit over cable television infrastructure

Router

Manages exchange of data between networks with IP address

• Direct/route packets between networks: determine optimal paths for data transmission (routing protocols and tables)

• Uses: destination IP address within each data packet + routing table = determine next hop for packet

• Maintain routing tables through dynamic/static routing protocols (learn network paths)

• Ex: connect multiple devices to internet and each other in residential setting = LAN

  • Home routers usually come with built-in wireless access points to support wifi connectivity

Switch

Connects devices within LAN

• Manages flow of data within network: receive, process, forward data packets/frames to correct destination device

  • Receive data packets

  • Use MAC address info within packet to forward to appropriate destination device

• Ex: connect computers, printers, storage devices in small/home office = share resources, communicate efficiently

Wireless Access Point (WAP)

interface between wired infrastructure and wireless devices

• Connect wired Ethernet data and wireless signals

• Integrate existing network infrastructure using standard network protocols

  • Can support security standards (WPA, WPA2, WPA3) to ensure encrypted connections

• = extends reach of network to areas w/o wiring (would be undesirable/impossible)

•  Ex: used in schools/universities to cover extensive campus area = access to resources and internet from any area

EXAMPLES

Which device is most appropriate for the given scenario?

A small home network needs to connect to the internet through an ISP. The device receives the signal from the telephone or fiber line and converts it into digital data the computer can understand.

Modem

In a large office, hundreds of computers need to share one internet connection. A device manages which data packets go to which destination IP address, ensuring the right computer gets the right data.

Router (since IP address)

Inside a company’s local network, a device connects multiple computers using Ethernet cables. It forwards data only to the specific computer it’s meant for instead of broadcasting to all devices.

Switch

In the school library, students connect their laptops, tablets, and phones wirelessly. The device that allows this connection is connected to the school’s main wired network.

WAP

A company’s internal LAN uses IPv4, while its external partner network uses IPv6. A device translates between these two different network protocols so they can communicate.

Gateway