Main

Physical Layer- Layer 1
What we can touch, measure and see
Uses logical addresses to route data
Cables, connectors and (hubs - amplify signals)
Dumb devices - they don't know where data is going and they don't care
Physical connectivity to the network

PDU/Protocol Data Unit - Bit / 1, 0
This layer converts packets from the data link layer into electrical signals
Cables
NIC - Network Interface Card

Troubleshooting