Fibre Channel Primer

41 Chapter 6: Topologies
Class 4: Fractional Bandwidth Acknowledged Connection-
Oriented Service
Figure 6.4 Class 3 service supports storage and networks
Class 4 is a fractional bandwidth, connection-oriented service.
Virtual connections are established with bandwidth reservation for
a predictable quality of service (QoS). A Class 4 connection is
bidirectional, with one virtual circuit (VC) operational in each
direction, and supports a different set of QoS parameters for each
VC. These QoS parameters include guaranteed bandwidth and
bounded end-to-end delay. A QoS facilitator (QoSF) function is
provided within the switch to manage and maintain the negotiated
QoS on each VC.
JBOD
Hub
Workstations
Switch
Server
Figure 6.5 Class 4 supports real-time applications
Video
Distribution
Network
Video
Server
Switch
Avionics