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Ebook TCP/IP essentials - A Lab-Based approach: Part 2

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(BQ) Part 2 book "TCP/IP essentials - A Lab-Based approach" has contents: TCP study, tulticast and realtime service; the Web, DHCP, NTP and NAT; network management and security. | 6 TCP study The flow on a TCP connection should obey a ‘conservation of packets’ principle. · · · A new packet isn’t put into the network until an old packet leaves. Van Jacobson 6.1 Objectives r r r r r r r r TCP connection establishment and termination. TCP timers. TCP timeout and retransmission. TCP interactive data flow, using telnet as an example. TCP bulk data flow, using sock as a traffic generator. Further comparison of TCP and UDP. Tuning the TCP/IP kernel. Study TCP flow control, congestion control, and error control using DBS and NIST Net. 6.2 TCP service TCP is the transport layer protocol in the TCP/IP protocol family that provides a connection-oriented, reliable service to applications. TCP achieves this by incorporating the following features. r Error control: TCP uses cumulative acknowledgements to report lost segments or out of order reception, and a time out and retransmission mechanism to guarantee that application data is received reliably. r Flow control: TCP uses sliding window flow control to prevent the receiver buffer from overflowing. 111 112 TCP study r Congestion control: TCP uses slow start, congestion avoidance, and fast retransmit/fast recovery to adapt to congestion in the routers and achieve high throughput. The TCP header, shown in Fig. 0.16, consists of fields for the implementation of the above functions. Because of its complexity, TCP only supports unicast, while UDP, which is much simpler, supports both unicast and multicast. TCP is widely used in internet applications, e.g., the Web (HTTP), email (SMTP), file transfer (FTP), remote access (telnet), etc. 6.3 Managing the TCP connection In the TCP header, the source and destination port numbers identify the sending and receiving application processes, respectively. The combination of an IP address and a port number is called a socket. A TCP connection is uniquely identified by the two end sockets. 6.3.1 TCP connection establishment A TCP connection is set up and maintained .