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1394 layer model

Four protocol layers are specified in the IEEE 1394 communication model, which serve the implementation of hardware and software. In the four layers - management layer, transaction layer, link layer and physical layer - services are provided for the layer above. Functionally comparable to the OSI reference model.

The management layer forms the top layer of the 1394 layer model and is responsible for managing the 1394 bus and the connected nodes. In addition to automatic configuration, each individual 1394 node supports various management functions for the power supply, and for globally connected nodes, global bus management with bandwidth allocation.

Under the management layer lies the transaction layer. On this layer the data transfers take place, which are released by the link layer lying under it with a request fortransactions. 1394 recognizes the three transaction types for reading, writing and locking. To handle the transactions, the requests from the Link Layer are broken down by the Transaction Layer into individual transactions, which are then executed. For this purpose, the Transaction Layer provides the well-known service primitives Request, Response, Indication and Confirmation.

The next layer down in the 1394 layer model is the Link Layer. This layer, called link layer, forms the interface between the physical layer with the transaction layer. In this layer the packetization of the data packets, the sending and receiving of the data packets as well as the error control takes place. The requests of the transaction layer are translated for this and packed into data packets, which are then passed on to the physical layer. On the other hand the data packets of a requesting node are depackaged and transferred to the transaction layer.

The physical layer, the physical layer, is based on the physical transmission medium. Functionally, bus initialization, signal level control, encoding and decoding, resynchronization, and fair allocation of available resources occur in this layer.

Data can be transmitted asynchronously and isochronously via the 1394 interface, with isochronous transmission being used for real-timemultimedia applications. With this type of transmission, a higher bandwidth is made available to the application.

Englisch: 1394 layer model
Updated at: 06.09.2012
#Words: 335
Links: protocol, IEEE 1394, communication (COM), implementation, hardware (HW)
Translations: DE

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