the transport layer segments and reassembles data into a data stream. Services located in the Transport layer segment and reassemble data from upper-layer applications and unite it into the same data stream. They provide end-to-end data transport services and can establish a logical connection between the sending host and destination host on an internetwork.
note : * Segmenting and reliable end-to-end data delivery occurs at the Transport layer *
the transport layer function :
- Fault detection
- Error recovery
- Establishing, maintaining, and tearing down virtual circuits
The Transport layer provide reliable networking :
- Acknowledgments : Delivered segments are acknowledged to the sender. If they are not acknowledged, the sender will retransmit.
- Sequencing : Data segments are sequenced into their original order when they arrive at the destination.
- Flow Control : Provides buffer controls that prevent packet flooding to the destination host. Buffers store bursts of data for processing when the transmission is complete.
the tranport layer protocols :
- Transmission Control Protocol (TCP)
- User Datagram Protocol (UDP)
- Sequenced Packet Exchange (SPX) : a reliable communications protocol created by Novell NetWare
note : * TCP and UDP protocols are important to know for the exam. These are discussed later in this chapter, under the “Transport Layer” section of the TCP/IP model *
glossary review :
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