TCP and UDP Protocols


Transport Layer

  • Session multiplexing
  • Flow control
  • Reliability
  • Segmentation
  • Uses TCP or UDP
  • Adds port number
  • Socket to socket


What is Port Number?

  • Service identifier
  • Length: 16 bits
  • Ranges from 0 to 65,535
  • Well-known ports: 0-1024
    • HTTP: 80
    • FTP: 21
    • DNS: 53
    • SMTP: 25
  • Ephemeral ports > 1024


UDP Protocol

  • Best-effort delivery (unreliable)
  • Provides applications with access to the network layer
  • Saves the overhead of reliability mechanisms
  • Connectionless protocol
  • Limited error checking
  • Data loss due to:
    • Routing error
    • Dupliation
  • No data-recovery features


TCP Protocol

  • Reliable protocol
  • Provides access to the network layer for applications
  • Connection-oriented protocol
  • Error checking
  • Data-recovery features
  • Sequencing of data packets
  • Acknowledgement of receipt
  • More commonly used than UDP


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