Shared Mode Versus Switched Mode; Shared Mode Operation And Logical Equivalent - McDATA StorageWorks 64 - SAN Director Switch Planning Manual

Shared Mode Versus
Switched Mode
D1
Figure 3-1
This section focuses on loop operation for Sphereon 4300 (12-port)
and 4500 (24-port) Fabric Switches that operate at 1.0625 or 2.1250
gigabits per second (Gbps) and support FC-AL operation using
FL_Ports and public and private device connectivity.
Legacy arbitrated loop switches (such as the McDATA ES-1000
Switch) are configured to operate in user-selectable shared or
switched mode.
NOTE: Sphereon 4300 and 4500 Fabric Switches do not support
shared mode operation.
Shared Mode Operation
When set to shared mode, a switch acts as a hub implementing
standard Fibre Channel arbitrated loop topology (although the loop
has the physical appearance of a star configuration) and distributes
the frame routing function through each loop port. When a loop
circuit is initialized and established, arbitration protocol ensures only
one device attached to a hub port (H_Port) owns the loop at a time.
The port establishes communication with another device attached to
an H_Port and allows the devices to transmit or receive frames.
During frame transmission between these devices, the full
bandwidth of the switch is used and no other H_Ports or devices are
available for connection. When frame transmission completes, the
loop circuit closes and other devices are able to contend for operation
(using standard loop arbitration). Shared mode operation and its
simplified logical equivalent are illustrated in
ES-1000 Switch
D2 S1

Shared Mode Operation and Logical Equivalent

Planning Considerations for Fibre Channel Topologies
Planning Considerations for Fibre Channel Topologies
Figure
A
Logical Equivalent
D1
H_Ports
3-1.
B
D2
S1
3-3
3