The Transport Layer(TCP/IP model)

Previous

The layer above the internet layer is the transport layer.It is designed to allow peer entities on source and destination hosts to carry on a conversation just as in OSI transport layer. Two end to end transport protocols have been defined here.
The first one TCP(Transmission Control Protocol) is a reliable connection oriented protocol that allows a byte stream originating on 1 machine to be delivered without error on any other machine on internet.
TCP also handle flow control to make sure a fast server cannot swamp a slow receiver.
The second protocol,UDP,(User Datagram Protocol) is an unreliable,connectionless protocol for applications that do not want TCP's sequencing or flow control and wish to provide their own.It is widely used for one shot,client-server type request-reply queries and applications in which prompt delivery is more important than accurate delivery such as transmitting speech or video.


Next

Reference Models

2 important n/w architectures:
The OSI reference model
& TCP/IP reference model

Although the protocols associated with the OSI model are rarely used any more,the model itself is general and still valid,and the features at each layer are still very important.
The TCP/IP model, the model itself is not of much use but the protocol are widely used.

OSI Model
OSI model is based on ISO as a first step toward international standardization of the protocols used in various layers.It deals with connecting open system-systems that are open for communication with other systems. The OSI model has 7 layers.

To be continued..