Layer 4. The Transport Layer

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Layer 4. The Transport Layer

This layer defines the rules for information exchange, manages the end-to-end flow control and delivery (for example, determining whether all packets have arrived), and error-checking / recovery within and between networks. It ensures complete data transfer.

This is the highest of the lower layer protocols in the OSI protocol stack. It provides the means to establish, maintain, and release transport connections on behalf of session entities. It provides a connection-oriented or connectionless service. In a connection-oriented session, a circuit is established through which packets flow to the destination (most protocols at this layer are connection-oriented). Error and flow control are dealt with at this layer (ACK). And most gateway functions are found at this level.

The Transport Layer is the first of what's called the "peer-to-peer" layers, which means that once the lower layers are implemented, a Transport Layer can transparently communicate directly with the Transport Layer of another data entity. It provides an idealized full duplex bit pipe to the upper layers in which the binary stream sent from one end, makes it, in order, to the other end. The result is that the upper layers get an idealized bit pipe and need only be concerned with what the data is, not how it arrived. Some protocols that reside at this level are TCP, UDP, SPX and TFTP.



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Going Wi-Fi. A Practical Guide to Planning and Building an 802.11 Network
Going Wi-Fi: A Practical Guide to Planning and Building an 802.11 Network
ISBN: 1578203015
EAN: 2147483647
Year: 2003
Pages: 273

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