Chapter 3

1. Chapter 3 TCP and IP Chapter 3 TCP and IP

2. Introduction • Transmission Control Protocol (TCP) • User Datagram Protocol (UDP) • Internet Protocol (IP) • IPv6 Chapter 3 TCP and IP

3. TCP • RFC 793, RFC 1122 • Outgoing data is logically a stream of octets from user • Stream broken into blocks of data, or segments • TCP accumulates octets from user until segment is large enough, or data marked with PUSH flag • User can mark data as URGENT Chapter 3 TCP and IP

4. Similarly, incoming data is a stream of octets presented to user • Data marked with PUSH flag triggers delivery of data to user, otherwise TCP decides when to deliver data • Data marked with URGENT flag causes user to be signaled Chapter 3 TCP and IP

5. Checksum Field • Applied to data segment and part of the header • Protects against bit errors in user data and addressing information • Filled in at source • Checked at destination Chapter 3 TCP and IP

6. Options • Maximum segment size • Window scale factor • Timestamp Chapter 3 TCP and IP

7. Figure 2.1 Chapter 3 TCP and IP

8. UDP • RFC 768 • Connectionless, unreliable • Less overhead • Simply adds port addressing to IP • Checksum is optional Chapter 3 TCP and IP

9. Appropriate Uses of UDP • Inward data collection • Outward data dissemination • Request-response • Real-time applications Chapter 3 TCP and IP

10. IP • RFC 791 • Field highlights: • Type of service, defined in RFC 1349, see Figure 3.1 • More bit • Don’t fragment bit • Time to live (similar to a hop count) Chapter 3 TCP and IP

11. Figure 2.2 Chapter 3 TCP and IP

12. Figure 3.1 Chapter 3 TCP and IP

13. Fragmentation and Reassembly • Networks may have different maximum packet size • Router may need to fragment datagrams before sending to next network • Fragments may need further fragmenting in later networks • Reassembly done only at final destination since fragments may take different routes Chapter 3 TCP and IP

14. Figure 3.2 Chapter 3 TCP and IP

15. Type of Service TOS Subfield • Set by source system • Routers may ignore TOS • Router may respond to requested TOS value through: • Route selection • Subnetwork service • Queuing discipline Chapter 3 TCP and IP

16. Table 3.1 Chapter 3 TCP and IP

17. Type of Service Precedence Subfield • Indicates degree of urgency or priority • Like TOS subfield, may be ignored and there are 3 approaches to responding • Intended to affect queuing discipline at router • Queue service • Congestion control Chapter 3 TCP and IP

18. IPv4 Options • Security • Source routing • Route recording • timestamping Chapter 3 TCP and IP

19. IPv6 • Increase IP address from 32 bits to 128 • Accommodate higher network speeds, mix of data streams (graphics, video, audio) • Fixed size 40-octet header, followed by optional extension headers • Longer header but fewer fields (8 vs 12), so routers should have less processing Chapter 3 TCP and IP

20. IPv6 Header • Version • Traffic class • Flow label • Payload length • Next header • Hop limit • Source address • Destination address Chapter 3 TCP and IP

21. IPv6 Addresses • 128 bits • Longer addresses can have structure that assists routing • 3 types: • Unicast • Anycast • multicast Chapter 3 TCP and IP

22. Figure 3.3 Chapter 3 TCP and IP

23. Optional Extension Headers • Hop-by-hop options • Routing • Fragment • Authentication • Encapsulating security payload • Destination options Chapter 3 TCP and IP

24. Figure 3.4 Chapter 3 TCP and IP