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CCNA 1 v3.0 Module 11 TCP/IP Transport and Application Layers. Objectives. TCP/IP Transport Layer TCP/IP Application Layer. TCP/IP Transport Layer. Introduction to Transport Layer. Five basic services : Segmenting upper-layer application data Establishing end-to-end operations
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CCNA 1 v3.0 Module 11 TCP/IP Transport and Application Layers
Objectives • TCP/IP Transport Layer • TCP/IP Application Layer
Introduction to Transport Layer • Five basic services: • Segmenting upper-layer application data • Establishing end-to-end operations • Transporting segments from one end host to another end host • Ensuring data reliability • Providing flow control
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
Session Establishment • One function of the transport layer is to establish a connection-oriented session between similar devices at the application layer.
Session Maintenance and Termination • Congestion can occur during data transfer • To terminate, the sending host sends a signal that indicates the end of the transmission, which is acknowledged by the receiver.
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
Window Size • TCP window sizes are variable during the lifetime of a connection. • Larger window sizes increase communication efficiency.
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.
Transmission Control Protocol (TCP) • The protocols that use TCP include: • FTP (File Transfer Protocol) • HTTP (Hypertext Transfer Protocol) • SMTP (Simple Mail Transfer Protocol) • Telnet
UDP • The protocols that use UDP include: • TFTP (Trivial File Transfer Protocol) • SNMP (Simple Network Management Protocol) • DHCP (Dynamic Host Control Protocol) • DNS (Domain Name System)
TCP and UDP Port Numbers • Both TCP and UDP use port (socket) numbers to pass information to the upper layers. • Numbers below 1024 are considered well-known ports numbers. • Numbers above 1024 are dynamically assigned ports numbers. • Registered port numbers are those registered for vendor-specific applications. Most of these are above 1024.
Responsibilities of Application Layer • Identifying and establishing the availability of intended communication partners • Synchronizing cooperating applications • Establishing agreement on procedures for error recovery • Controlling data integrity
Application Layer Examples • Domain Name System • File Transfer Protocol • Hypertext Transfer Protocol • Simple Mail Transport Protocol • Simple Network Management Protocol • Telnet
DNS • The Domain Name System (DNS) is a system used for translating names of domains into IP addresses. • There are more than 200 top-level domains on the Internet, examples of which include the following: • .us – United States • .uk – United Kingdom • .edu – educational sites • .com – commercial sites • .gov – government sites • .org – non-profit sites • .net – network service
FTP and TFTP • FTP is a reliable, connection-oriented service that uses TCP to transfer files between systems that support FTP. • TFTP is a connectionless service that uses User Datagram Protocol (UDP). • TFTP is used on routers to transfer configuration files and Cisco IOS images. • TFTP is designed to be small and easy to implement.
SMTP • E-mail servers communicate with each other using the Simple Mail Transport Protocol (SMTP) to send and receive mail.
SNMP • The Simple Network Management Protocol (SNMP)is an application layer protocol that facilitates the exchange of management information between network devices.
Telnet • Telnet client software provides the ability to login to a remote Internet host that is running a Telnet server application and then to execute commands from the command line.