Fibre Channel Primer

38 Fibre Channel: Connection to the Future
CLASSES OF SERVICE
Fibre Channel meets the requirements of a wide range of applications
with switches and nodes supporting one or more Classes of Service.
No manual set up is required, since Classes of Service that are
supported between switches and nodes are determined during login.
Class 1: Acknowledged Connection Service
Class 1 provides true connection service. The result is circuit-
switched, dedicated bandwidth connections. Fibre Channel’s
advantage is connection setup and tear-down measured in
microseconds.
An end-to-end path between the communicating devices is
established through the switch. Since the only overhead for Class 1
Table 6.1 Fibre Channel Classes of Service
Node-to-Node
after Connection
Reliable and
Dedicated
Large Files and
Full-Bandwidth Service
Buffer-to-Buffer
Node-to-Node
Reliable and
Multiplexed
Clustering,
Networking, OLTP
Buffer-to-Buffer
Datagram and
Multiplexed
Storage, Networking,
Broadcast, Multicast
Buffer-to-Buffer
Node-to-Node
Reliable and
Guaranteed with
Quality of Service
Real-Time Systems,
Real-Time Audio/Video
Node-to-Node
after Connection
Reliable and
Dedicated, assisted
by Multicast Server
Video Distribution
(One to Many)
Data Acquisition
-Class 1-
Acknowledged
Connection
Service
-Class 2-
Acknowledged
Connection
Service
-Class 3-
Unacknowledged
Connection
Service
-Class 4-
Fractional
Bandwidth
Connection-
Oriented Service
-Class 6-
Uni-Directional
Connection
Service
Credit-Based
Flow Control
Delivery Use