Transport Layer (Layer 4)

  • Responsible for transporting application payloads across network connections
  • Two main protocols:
    • TCP
      • Makes connection with end host
      • Checks whether or not data was received
      • Connection-oriented protocol
      • If messages are too large, breaks them into segments
    • UDP
      • Does not guarantee delivery
      • Connectionless protocol
      • Message is called a datagram
  • Protocols add their own control info at the beginning of a payload
    • A header
    • Process of adding a header to data from layer above is called encapsulation
  • Communicates between the session layer and the network layer

Computer Science Networking OSI Model