Classes Of Service; Arbitrated Loop Topology - LSI LSIFC929 Technical Manual

2.7 Classes of Service

Figure 2.9

Arbitrated Loop Topology

NL_Port
NL_Port
NL_Port
NL_Port
There are several classes of service in FC. The different classes are
distinguished from each other in three ways: by the level of guarantee for
data being delivered, the order in which data is delivered, and how data
flow control is maintained.
Class 1 is a dedicated connection between two N_Ports. The data
delivered is guaranteed with a required acknowledgement frame (ACK),
which a Class 1 device uses for flow control. All frames are received in
order.
Class 2 is a connectionless class. The data delivered is guaranteed with
an ACK frame. The frames can be received out of order. Class 2 uses
both ACK frames and the R_RDY Ordered Set for flow control.
Class 3 is also a connectionless class (the data being delivered is not
guaranteed). The frames can be received out of order. Class 3 uses only
the R_RDY Ordered Set for flow control.
Classes of Service
Copyright © 2000, 2001 by LSI Logic Corporation. All rights reserved.
NL_Port
Private Loop
NL_Port
Fabric
Element
FL_Port
Public Loop
NL_Port
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