cs-notes

SYN
- Synchronization
  - Sequence Number
ACK
- Acknowledge
  - SN + 1
FIN
- Finish
  - terminate connection gracefully
  - only one side of the conversation is stopped
  - no data loss
  - receiver of FIN keeps communicating till it wants to
RST
- Reset
  - condition
    - sender feels something is wrong with the TCP connection
      - eg. receive unexpected FLAG or sequence number
    - the conversation should not exist
  - tell the other side to stop communication
  - the whole conversation is stopped
  - data is discarded
  - receiver has to stop communication
PSH
- Push
  - All data in buffer to be pushed to NL(sender) / AL (receiver)
  - Data is delivered in sequence
URG
- Urgent
  - Only the urgent data to be given to AL immediately
  - Data is delivered out of sequence