TABLE OF CONTENTS Flow control is a tremendously important factor influencing the performance of any data communications architecture. This is particularly true in a multiplexed networking environment, where the aggregate bandwidth of multiple sources sending simultaneously would overwhelm the reception capacity of any practical destination receiver implementation, if no flow control were imposed.
This chapter covers the flow control mechanisms used in the Fibre Channel architecture for assuring flow control at the link, Frame, N_Port, and Fabric levels. Several of the various flow control mechanisms which have been developed for network data communications are described in the General Strategies section, on page 262. The strategies used in the Fibre Channel architecture are enumerated in the Fibre Channel Flow Control Strategies section, on page 263. In particular, the end-to-end flow control strategies used between N_Ports is described in the End-to-End Flow Control section, on page 265, and the link-level buffer-to-buffer flow control mechanism is described in the Buffer-to-Buffer Flow Control section, on page 270. Finally, the Integrated Flow Control for Class 2 Service section, on page 272 describes the interaction of buffer-to-buffer and end-to-end flow control mechanisms for Class 2 traffic.
In any communication system, a great deal of attention must be paid to flow control, to assure that no Port is flooded by more data than it can handle. This is particularly important on a switched network communication Fabric, where multiple sources may be attempting to send data to a single destination simultaneously, generating more transmission data than can possibly...
