3.6: Network Hardware & Routing
Eduqas / WJEC
A hub receives data packets from a connected device and transfers a copy to all connected nodes.
A switch receives data packets, processes them and transfers them on to the device specifically listed in the destination address of the packet.
Routers are used to transfer data packets between networks.
Data is sent from network to network on the internet towards the destination address listed in the data packet.
A router stores the address of each computer on the network and uses routing tables to calculate the quickest and shortest path.
A bridge joins together two networks that use the same base protocols.
For example, a bridge could link together a LAN to another LAN.
Network Interface Card (NIC)
A Network Interface Card (often shortened to NIC) is an internal piece of hardware that is required for the computer to connect to a network.
It used to be a separate expansion card but now it is commonly built directly into the motherboard (and sometimes known as a network adapter).
Wireless network interface cards (WNIC) permit a wireless network connection.
A routing table is a list of the optimal routes for data packets to be sent from one device to another.
Routing tables should be kept accurate and up to date to ensure that packets are transferred as quickly as possible.
During routing the lowest cost route is calculated. This is the shortest path with the fastest nodes to transfer data.
Below is a simplified network and basic routing table showing the lowest cost (optimal) route using node A as the source address.
3.6 - Network Hardware & Routing:
1a. Describe the difference between a hub and a switch. 
1b. Explain how a modem works. 
1c. Describe the purpose of a router. 
1d. Describe the difference between a gateway and a bridge. 
1e. State what NIC stands for and why it is required. 
2a. Describe what a routing table is and why they should be maintained. 
2b. In terms of routing, what does a low-cost route mean? 
2c. Copy and complete the routing table below using node J as the source address. 
Modems are used to send data across the telephone network.
The telephone lines can only transfer analog signals so a modem is used to convert a computer's digital data into an analog signal.
Another modem converts the signal back to a digital format at the receiving end.
A gateway joins together two networks that use different base protocols.
For example, a gateway could link together a LAN to a WAN.