TCP/IP Transport and Application (Topic 6) Textbook: Networking Basics, CCNA 1 Companion Guide, Cisco Press Cisco Networking Academy Program, CCNA 1 and 2, Companion Guide, Cisco Press, Latest Edition CIM 2465 TCP/IP Transport and Application Layers

TCP/IP Transport Layer (1) Main goal of the Transport Layer To provide the service of taking data from one application process on one computer and delivering that data to the correct application process on another computer Compare with the Internet layer, it delivers data packets from one computer to another, but it does not think about which application sent the data or which application on the receiving computer needs the data Key protocols Transmission Control Protocol (TCP) User Datagram Protocol (UDP) TCP provides several more functions, but more overhead CIM 2465 TCP/IP Transport and Application Layers

CIM 2465 TCP/IP Transport and Application Layers TCP Vs UDP CIM 2465 TCP/IP Transport and Application Layers

CIM 2465 TCP/IP Transport and Application Layers Flow Control When a host sends data using TCP, the receiving host can control how fast each TCP sender sends the data over time. This process is called flow control. Why needed? Receiver needs time to process the received data Receiver might have a finite amount of memory for processing of data TCP has flow-control mechanism CIM 2465 TCP/IP Transport and Application Layers

Connection-Oriented Vs Conncetionless Connectionless The sender and receiver do not pre-arrange for communication to occur Connection-oriented The sender and receiver must pre-arrange for communication to occur (use messages, events, or other prearranged settings) TCP is a connection-oriented protocol, uses a process called a three-way handshake CIM 2465 TCP/IP Transport and Application Layers

Three-Way TCP Connection CIM 2465 TCP/IP Transport and Application Layers

Error Recovery (Reliability) Reliable protocols perform error recovery, which means that they ensure that all the data eventually gets to the receiver No data loss No data duplicated Data received in correct sequence (in order delivery) TCP is a reliable protocol, through the use of Acknowledgements CIM 2465 TCP/IP Transport and Application Layers

CIM 2465 TCP/IP Transport and Application Layers TCP Acknowledgements CIM 2465 TCP/IP Transport and Application Layers

Segmentation, Reassembly, and In-Order Delivery TCP segmentation refers to the process of TCP accepting a large chunk of data from application protocol and breaking it into pieces that are small enough to be appropriate for transmission TCP on the receiving end reassembles the data into its original form, and guarantees that the data will be in order Through the use of a Sequence Number CIM 2465 TCP/IP Transport and Application Layers

CIM 2465 TCP/IP Transport and Application Layers Port Numbers One function performed by both UDP and TCP is providing a means to identify the specific application processes that send and receive data Through the use of Port Numbers < 1024, reserved, Well-Known ports 1024 - 65535, dynamic port numbers CIM 2465 TCP/IP Transport and Application Layers

CIM 2465 TCP/IP Transport and Application Layers An IP packet with TCP segment arrives at Keith’s Computer TCP examines the destination port number Based on the port number, the TCP software gives the data to Browser2 CIM 2465 TCP/IP Transport and Application Layers

CIM 2465 TCP/IP Transport and Application Layers Well-Know Ports (1) CIM 2465 TCP/IP Transport and Application Layers

CIM 2465 TCP/IP Transport and Application Layers Well-Know Ports (2) CIM 2465 TCP/IP Transport and Application Layers

CIM 2465 TCP/IP Transport and Application Layers TCP Header Fields Key Fields Source Port Destination Port Sequence Number Acknowledgement Number Checksum CIM 2465 TCP/IP Transport and Application Layers

CIM 2465 TCP/IP Transport and Application Layers TCP Header Fields CIM 2465 TCP/IP Transport and Application Layers

CIM 2465 TCP/IP Transport and Application Layers UDP Header Fields Key Fields Source Port Destination Port Length Checksum CIM 2465 TCP/IP Transport and Application Layers

TCP/IP Application Layer TCP/IP application layer performs the same functions as defined in the top three layers of the OSI reference model TCP/IP application protocols define the format of the data being transferred (binary or ASCII), required encryption, protocol rules for transferring data, combinations of messages (dialogues or sessions) Application software (e.g. browsers) typically implements application layer protocols CIM 2465 TCP/IP Transport and Application Layers

CIM 2465 TCP/IP Transport and Application Layers

Application Protocol Examples (1) Domain Name System (DNS) Resolves names into IP addresses UDP Hypertext Transfer Protocol (HTTP) Transfers files from web servers to web browsers TCP Simple Mail Transfer Protocol (SMTP) and Post Office Protocol version 3 (POP3) Send and receive e-mail, respectively File Transfer Protocol (FTP) Stores and retrieves files CIM 2465 TCP/IP Transport and Application Layers

Application Protocol Examples (2) Trivial File Transfer Protocol (TFTP) Works similarly to FTP, but with some benefits when used on networking devices UDP Simple Network Management Protocol (SNMP) Allows management software (the client) to query networking devices (the servers) to manage and control the networking devices Telnet Allows a client to emulate a terminal. It allows a user to sit at one computer (Telnet client) and use a remote computer (Telnet server) through a text-based interface TCP CIM 2465 TCP/IP Transport and Application Layers

CIM 2465 TCP/IP Transport and Application Layers DNS CIM 2465 TCP/IP Transport and Application Layers

CIM 2465 TCP/IP Transport and Application Layers HTTP CIM 2465 TCP/IP Transport and Application Layers

CIM 2465 TCP/IP Transport and Application Layers SMTP and POP3 CIM 2465 TCP/IP Transport and Application Layers

CIM 2465 TCP/IP Transport and Application Layers FTP CIM 2465 TCP/IP Transport and Application Layers