Chapter 3 TCP and IP 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