3. Interface to applications using socket 4. Interface to
host-to-host packets 5. Sockets and the magic portal
Sockets are your friend
6. Hides the network issues 7. Data stream just arrives as
streams 8. Transport layer (sending) 9. Transport layer (receiving)
10. Problems
No delivery guarantee
Lost segments?
11. Out-of-order segments? 12. Protocols
UDP
Simple, fast, unreliable
TCP
Complex, slow, reliable.
Others exists 13. UDP
Connectionless
No feedback on send data.
Simple checksum verification 14. Used by
DNS, skype, SNMP,
15. TCP
Data received acknowledgement
16. Order ensured 17. Packets are resend on failure 18. Advanced
features like congestion control. 19. TCP sending data 20. TCP -
handshakes Initial handshake Closing handshake 21. Wireshark
exercises
