Elementary data link protocols
Frame contents - kind, seq_no, ack, info
- First 3 contain control info and the last contains actual data.
- kind lets us know if frame contains only control info. or if it contains control info. + data.
- seq_no is used to number frames to tell them apart
- ack is used for acknowledgements
- info field of data frame contains a single packet. For a control frame info field is not used.