Framing
The typical packet structure is
- Preamble: Existence of packet and synchronization of clocks
- Header: Addresses, Type, Length
- Data: Payload plus higher layer levels (e.g. IP Packet)
- Trailer: Padding CRC
Error Control
We want to make sure we can detect errors in the packet and discard them. We have Cyclical Redundancy Checks which detects single bit errors.
We also want to recover from small bit errors.