VeEX MTX150 Series, Руководство пользователя

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Key Test Applications
Transport layer - Most customers or providers transporting Fibre Channel are not necessarily trained or con-
cerned with testing the higher protocol layers -- instead the transport groups tasked with transporting this data
across a point-to-point or ring type DWDM network are more likely to ask: Did data arrive error free or were any
bit errors encountered? Was the CRC corrupted or were any code violations experienced? Testing the trans-
port layer is crucial and normally includes the FC-0 Layer, FC-1 Layer, and parts of the FC-2 Layer where:
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FC-0 addresses the physical layer: the optical fiber, connectors, and associated optical signal para-
meters.
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FC-1 addresses the transmission protocol encoding/decoding, and special characters used for pro-
tocol management.
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FC-2 addresses the signaling protocol layer, which comprises the framing protocol and the flow con-
trol process.
The Fibre Channel option addresses all the transport layers by measuring the optical power level and sup-
porting the generation/analysis of bit errors, order sets, frame delimiters, frame transmission, and the gen-
eration of primitive sequences. User defined bytes, fixed test patterns or industry-standard PRBS patterns can
be selected and inserted into the payload field depending on the test layer. Bit error, CRC error and Code viol-
ation insertion are useful features to verify Mux/Demux equipment for error monitoring and detection.
Buffer-to-Buffer Credit Estimation - To avoid loss of frames during transmission, the Fibre Channel protocol
uses a buffer-to-buffer flow control mechanism between link partners. During the login process, the remote
node informs the local nodes as to the number of receive buffers it has available. For each frame received, the
remote port returns a R_RDY frame to indicate that one of the receive buffers is now free - the local port in turn
increments its available credit counter by one for each R_RDY acknowledgment frame it receives. However,