HP Surestore 64 FW 05.01.00 and SW 07.01.00 HP StorageWorks SAN High Availabil - Page 70

Switched Mode Operation, Switched mode operation and logical equivalent,

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Planning Considerations for Fibre Channel Topologies Switched Mode Operation When set to switched mode (default setting), a loop switch enables frame transmission through multiple point-to-point connected pairs. Switched mode operation and its simplified logical equivalent are illustrated in Figure 29. Part (A) of Figure 29 shows server S1 connected to device D1 through a switched pair of H_Ports, communicating at 1.0625 Gbps. Server S2 is connected to device D2 through a second switched pair of H_Ports, also communicating at 1.0625 Gbps. Because of opportunistic bandwidth sharing, the two switched pairs effectively increase the switch bandwidth to 2.125 Gbps. The remaining switch H_Ports (four ports) are available for switched connection to each other, but cannot communicate with servers S1 and S2 or devices D1 and D2. Part (B) of Figure 29 shows the logical equivalent of this arbitrated loop. A Logical Equivalent B Loop Switch H_Ports S1 D1 S2 D2 S1 D1 S2 D2 Figure 29: Switched mode operation and logical equivalent Switched mode also allows independent operation of looplets of devices, each connected through an unmanaged hub, and each attached to a single switch H_Port. Figure 30 shows 8 hubs, each connected to a switch H_Port, and each connected to a pair of devices (16 devices total). Each device pair forms a looplet that communicates through a hub and connecting H_Port, and because of opportunistic bandwidth sharing, the looplets effectively increase the switch bandwidth to 8.5 Gbps. 70 SAN High Availability Planning Guide

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Planning Considerations for Fibre Channel Topologies
70
SAN High Availability Planning Guide
Switched Mode Operation
When set to switched mode (default setting), a loop switch enables frame
transmission through multiple point-to-point connected pairs. Switched mode
operation and its simplified logical equivalent are illustrated in
Figure 29
.
Part (A) of
Figure 29
shows server S
1
connected to device D
1
through a switched
pair of H_Ports, communicating at 1.0625 Gbps. Server S
2
is connected to device
D
2
through a second switched pair of H_Ports, also communicating at 1.0625
Gbps. Because of opportunistic bandwidth sharing, the two switched pairs
effectively increase the switch bandwidth to 2.125 Gbps. The remaining switch
H_Ports (four ports) are available for switched connection to each other, but
cannot communicate with servers S
1
and S
2
or devices D
1
and D
2
. Part (B) of
Figure 29
shows the logical equivalent of this arbitrated loop.
Figure 29:
Switched mode operation and logical equivalent
Switched mode also allows independent operation of looplets of devices, each
connected through an unmanaged hub, and each attached to a single switch
H_Port.
Figure 30
shows 8 hubs, each connected to a switch H_Port, and each
connected to a pair of devices (16 devices total). Each device pair forms a looplet
that communicates through a hub and connecting H_Port, and because of
opportunistic bandwidth sharing, the looplets effectively increase the switch
bandwidth to 8.5 Gbps.
H_Ports
D1
D2
D2
S2
S1
D1
S1
S2
A
B
Logical Equivalent
Loop Switch