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CCNA 1 Chapter 9 TCP/IP Transport and Application Layers By Your Name Copyright 2003 www.ciscopress.com Objectives • TCP/IP transport layer • TCP/IP application layer Copyright 2003 www.ciscopress.com Routed Protocols Versus Routing Protocols Routing protocols determine the path that routed protocols follow to their destinations. Copyright 2003 www.ciscopress.com The Transport Layer Functions Five basic services: • Segmenting upper-layer application data • Establishing end-to-end operations • Sending segments from one end host to another end host • Ensuring data reliability • Providing flow control Copyright 2003 www.ciscopress.com Flow Control • Avoids the problem of a host at one side of the connection overflowing the buffers in the host at the other side • Ensures the integrity of the data Copyright 2003 www.ciscopress.com Session Establishment Copyright 2003 www.ciscopress.com Three-Way Handshake Copyright 2003 www.ciscopress.com Windowing • A method of controlling the amount of information transferred end to end • Information can be measured in terms of the number of packets or the number of bytes Copyright 2003 www.ciscopress.com Window Size Larger window sizes increase communication efficiency. Copyright 2003 www.ciscopress.com Acknowledgment • Positive acknowledgment requires a recipient to communicate with the source, sending back an acknowledgment message when it receives data. • Sender keeps a record of each data packet that it sends and expects an acknowledgment. Copyright 2003 www.ciscopress.com Layer 4 Protocols Copyright 2003 www.ciscopress.com TCP • • • • Connection oriented Reliable Divides outgoing messages into segments Reassembles messages at the destination station • Resends anything not received • Reassembles messages from incoming segments Copyright 2003 www.ciscopress.com UDP • • • • Connectionless Unreliable Transmits messages (called user datagrams) Provides no software checking for message delivery (unreliable) • Does not reassemble incoming messages • Uses no acknowledgments • Provides no flow control Copyright 2003 www.ciscopress.com TCP/IP Protocol Graph Copyright 2003 www.ciscopress.com TCP Segment Format Copyright 2003 www.ciscopress.com UDP Segment Format Copyright 2003 www.ciscopress.com Port Numbers Copyright 2003 www.ciscopress.com Application Layer Copyright 2003 www.ciscopress.com TCP/IP Application Layer Copyright 2003 www.ciscopress.com Responsibilities • Identifying and establishing the availability of intended communication partners • Synchronizing cooperating applications • Establishing agreement on procedures for error recovery • Controlling data integrity Copyright 2003 www.ciscopress.com Application Layer Examples • • • • • • Domain Name System File Transfer Protocol Hypertext Transfer Protocol Simple Mail Transport Protocol Simple Network Management Protocol Telnet Copyright 2003 www.ciscopress.com Domain Name System Copyright 2003 www.ciscopress.com FTP • FTP is a reliable, connection-oriented service that uses TCP to transfer files between systems that support FTP. Copyright 2003 www.ciscopress.com HTTP Copyright 2003 www.ciscopress.com SMTP • E-mail servers communicate with each other using the Simple Mail Transport Protocol (SMTP) to send and receive mail. Copyright 2003 www.ciscopress.com SNMP • The Simple Network Management Protocol (SNMP) is an application layer protocol that facilitates the exchange of management information between network devices. • An SNMP managed network consists of the following: – Network management system (NMS) – Managed device – Agents Copyright 2003 www.ciscopress.com Telnet • Telnet client software provides the ability to log in to a remote Internet host that is running a Telnet server application and then to execute commands from the command line. Copyright 2003 www.ciscopress.com