Seagate Fibre Channel Interface - Manual (Page 46)

32 Fibre Channel Interface Manual, Rev. D
• EE_Credit not required
• Busy and Reject not needed due to alternate credit model
• Errors are recovered at the exchange level
7.3.1 Class 3 flow control
Class 3 flow control is a simple model which does not require EE_Credits. With Class 3, there is only buffer-to-
buffer flow control in one direction and there are no link level responses to Class 3 frames.
7.4 Classes 4 and 5
Classes 4 and 5 are being defined by Fibre Channel committees to aid audio and video applications.
Class 4 is similar to Class 1 in that a dedicated connection is established; however, with Class 4, the full band-
width is not available. Connections for other nodes connected may be assigned portions of the bandwidth.
Class 5 provides isochronous service through a fabric. A Class 5 node is guaranteed access through a fabric
at established time intervals.