Transport Layer OSI Model
The transport layer is responsible for the segmentation and the delivery of a message from one process to another.
Transport layer SenderReceiver
Transport Layer Ensures that the data units are delivered error free. Ensures that data units are delivered in sequence. Ensures that there is no loss or duplication of data units. Provides connectionless or connection oriented service. Provides for the connection management. OSI Model
Transport Layer Provides reliable data delivery It’s the TCP in TCP/IP Receives info from upper layers and segments it into packets Can provide error detection and correction 3
Transport Layer Facilitates end to end communication over internetwork Allows logical connections between devices via unreliably and reliably Identification of the specific source and destination are noted
Transport Layer Segmentation - Transport layer protocols break large data units received from Session layer into smaller segments Maximum transmission unit (MTU): largest data unit a given network will carry Reassembly: process of reconstructing segmented data units Sequencing: method of identifying segments that belong to same group of subdivided data
Transport Layer Segmentation and Reassembly
Connection Oriented / Connectionless Connection Oriented – when devices communicate, they perform handshaking to set up an end-to-end connection. Connectionless - usually achieved by transmitting information in one direction, from source to destination without checking to see if the destination is still there, or if it is prepared to receive the information
Transport Layer Protocols UDP (User Datagram Protocol) - service provided by UDP is unreliable that provides no guarantees for delivery and no protection from duplication Connectionless protocol TCP (Transmission Control Protocol) -a connection- oriented reliable protocol. approximately 90% of current traffic uses this transport service no loss, no duplication, FIFO, must be delivered within a reasonable time