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Originally Posted by nyne  Is this unique to MHLabs ? The popular belief is that the slowest link in the FW chain brings the whole bus down to that speed...... |
It is not unique to MHLabs. Popular does not equal correct.
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Originally Posted by nyne i:e in the above chain, the M I/O would bring down the whole bus to FW400 and the Drive would also communicate at FW400. |
This is not correct. All traffic to the FW400 device will be at s400, but if the FW800 devices are connected together with FW800 cabling (and not through a FW400 device or hub nor with FW400 cabling) then the FW800 devices will use s800 for communications between themselves. Speed is determined on a packet by packet basis in FireWire, and the system knows the maximum speed supported between any two nodes.
So, it is incorrect to think that attaching a FW400 device to a FW800 bus will slow the entire bus down to FW400 for all transactions. It only places a bottleneck on the transactions that have to pass through the FW400 device.
Best regards,