Ethernet

Ethernet is a very common Link Network Layer protocol
- The job of Ethernet is to transport data around a local network
Ethernet’s job is to take whatever ‘payload’ it is given and physically transport it around a compatible network (one running the Ethernet protocol)
- The protocols sitting above this layer don’t need to concern themselves with how the data will be transmitted (e.g. the type of network, etc.)
Other network connection types will require their own Link Network Layer, such as 802.11x (wireless), DSL, Bluetooth, FDDI
Ethernet is local because it does not understand what a ‘network’ is, all it knows is how to ‘find’ devices it can talk to
Ethernet uses a 48-bit unique address to differentiate between devices it can talk to
- This is the MAC address (Media Access Control)
- An Ethernet address and MAC address are the same thing
This is why all network devices have a MAC address
- e.g. If you have 3 network cards, you’ll have 3 MAC addresses

Network Equipment

The types of hardware that communicate with Ethernet at the Link Network Layer are those that talk MAC addresses:
- Hub
- Switch