UniPro protocol stack: Difference between revisions

Revision as of 14:49, 1 April 2011

Revision as of 14:51, 1 April 2011

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==Transport Layer (L4)==

The features of UniPro's Transport layer are not especially complex, but are a bit subtle because basic communication services have already been taken care of by lower protocol layers. L4 is essentially about enabling multiple devices on the network or even multiple clients within these devices to share the network in a controlled manner. L4's features tend to be roughly comparable to features found in computer networking (e.g. [[Transmission Control Protocol|TCP]] and [[User Datagram Protocol|UDP]]) but that are less commonly encountered in local busses like PCI Express, USB or on-chip busses.

UniPro's L4 also has special significance because it is the top protocol layer in the UniPro specification. Applications are required to use L4's top interface to interact with UniPro and are not expected to bypass L4 to directly access lower layers. Note that the interface at the top of L4 provided for transmitting or receiving data is defined at the behavioral or functional level. This high level of abstraction avoids restricting implementation options. Thus, although the specification contains an annex with a signal-level interface as a non-normative example, a UniPro implementation is not required to have any specific set of hardware signals or software function calls at its topmost interface.