Chapter IV and V.pptx - Chapter IV Transport Layer Contents 2 Transport layer and its service Elements of Transport Protocols Reliable Data Transfer TCP

Chapter IV and V.pptx - Chapter IV Transport Layer Contents...

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Chapter IV Transport Layer
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Contents Transport layer and its service Elements of Transport Protocols Reliable Data Transfer: TCP Connectionless Transport: UDP Congestion Control 07/06/2019 Ayuyazi 2
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Transport Layer and its services The transport protocol provides an end-to-end (process-to-process) data transfer service that shields upper-layer protocols from the details of the intervening network or networks. A transport protocol can be either connection oriented or connectionless. If the underlying network or internetwork service is unreliable (i.e. IP), then a reliable connection- oriented transport protocol becomes quite complex. The basic cause of this complexity is the need to deal with the relatively large and variable delays experienced between end systems. 4 07/06/2019 Ayuyazi
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Transport Layer cont….. 5 07/06/2019 Ayuyazi
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Elements of Transport Protocols Process to Process communication The first duty of a transport-layer protocol is to provide process-to-process communication. A process is an application-layer entity that uses the services of the transport layer. A transport-layer protocol is responsible for delivery of the message to the appropriate process. 07/06/2019 Ayuyazi 6
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Elements of Transport Protocols cont…. Addressing: Port Numbers For the purpose of process to process communication, we must define the local host, local process, remote host, and remote process. The local host and the remote host are defined using IP addresses. To define the processes, we need second identifiers, called port numbers. The client program and the server process define their own port number (mostly temporary and permanent respectively). 7 07/06/2019 Ayuyazi
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Elements of Transport Protocols cont… Multiplexing/demultiplexing With respect to the interface between the transport protocol and higher-level protocols, the transport protocol performs a multiplexing/demultiplexing function. The transport layer at the source performs multiplexing; the transport layer at the destination performs demultiplexing. That is, multiple users employ the same transport protocol and are distinguished by port numbers or service access points. The transport entity may also perform a multiplexing function with respect to the network services that it uses. 8 07/06/2019 Ayuyazi
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Elements of Transport Protocols cont… Flow Control Whenever an entity produces items and another entity consumes them, there should be a balance between production and consumption rates. If the sender delivers items whenever they are produced without a prior request from the consumer the delivery is referred to as pushing. If the producer delivers the items after the consumer has requested them, the delivery is referred to as pulling.
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  • Transmission Control Protocol, Transport Protocols,  Transport layer

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