Fibre Channel Overview
Working With Fibre Channel
The Fibre Channel protocol will work when devices are connected or disconnected while data is being transferred because of this additional information. Error detection and recovery at all levels of the protocol are also provided.
A fairness algorithm is built into the FCAL protocol so that all devices have equal access to the system. To keep the phase lock loops synchronized, Fibre Channel continually communicates, even between frames, supporting device arbitration for access to the loop. Fibre Channel devices also use this communication to report on buffer size available for communication. If there is nothing to report, the Fibre Channel protocol fills up the space between frames with idle characters. Characters must be present on the bus at all times to keep the high frequency circuits working correctly, reconstructing data clocks and detecting data on the bus. Even the data encoding is arranged so that there is never a continuous string of ones or zeros.
The lower levels of Fibre Channel protocol is handled in the hardware and, to a minor extent, by the low level HBA drivers. System and application software does not need to be aware of any low level protocol operations. Additional features exist in the protocol that more advanced applications can use.
Fibre Channel addressing introduces three major advantages:
•Provides large number of addresses
•Detects address conflicts
•Automatically reassigns new addresses when conflicts occur
With Fibre Channel, the data network can be distributed and very large. The ANSI Fibre Channel committee developed a method that devices must use to check and report addresses before data can be sent or received. ANSI also added the ability to
Overview | Fibre Channel |
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Appendix A |
