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
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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