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32d. Layer 5 - Session Layer |
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32d. Layer 5 - Session Layer
The Session layer manages the communications between the workstation and network. The Session layer directs the information to the correct destination and identifies the source to the destination. The Session layer identifies the type of information as data or control. The Session layer manages the initial start-up of a session and the orderly closing of a session. The Session layer also manages Logon procedures and Password recognition. See Fig. 5.
Fig. 5 Session Layer
In order for the data to be sent across the network, the file must be broken up into usable small data segments (typically 512 - 18K bytes). The Transport layer breaks up the file into segments for transport to the network and combines incoming segments into a contiguous file. The Transport layer does this logically not physically, it is done in software as opposed to hardware.
The Transport layer provides error checking at the segment level (frame control sequence). This checks that the datagrams are in the correct order and the Transport layer will correct out of order datagrams. The Transport layer guarantees an error-free host to host connection, it is not concerned with the path between machines.