lecture4:OSI Transport Layer Protocol

A protocol is a set of rules. The OSI model provides a framework for the communication protocols used between computers. Just as we need rules of the road—for example, so that we know that a red light means stop and a green light means go—computers also need to agree on a set of rules to successfully communicate.

Two computers must use the same protocol to communicate. Computers that try to use different protocols would be analogous to speaking in Italian to someone who understands only English—it would not work.

Many protocol suites define various protocols that correspond to the functions defined in the seven OSI layers, including routed protocols, a selection of routing protocols, applications, and so forth. Protocol suites are also known as protocol stacks.

The most widely used network protocol suite today is the TCP/IP suite.
Application layer examples include:
• Dynamic Host Configuration Protocol (DHCP) :Enables devices on a network to obtain IP addresses and other information from a DHCP server. DHCP allows a host to obtain an IP address dynamically when it connects to the network.

• File Transfer Protocol (FTP) : FTP was developed to allow for file transfers between a client and a server . (FTP) Protocol is used for interactive file transfer between systems.

• Simple Mail Transfer Protocol (SMTP) : is used for the transfer of mail messages and attachments.

• Terminal Emulation Protocol (Telnet): is used to provide remote access to servers and networking devices.