HP P4459A manual Switching Operation, Switching Using Fibre Channel Protocol

HP P4459A 8-Port Fibre Loop Switch Installation & Operation Guide

Switching Operation

The fibre loop switch implements the Fibre Channel Arbitrated Loop protocol. It provides concurrent connections to the storage area network (SAN) without changing the FC-AL interface, which most SAN end-node devices normally communicate.

The SAN operation changes dramatically when comparing a switch with a hub environment. The normal operation, as seen by a single end-node device, does not change, other than a rapid acceleration of responses in a switch environment. Figure 3 illustrates how the fibre loop switch alters the response speed without changing the nature of the responses seen by a participating node.

Figure 3: Switching Using Fibre Channel Protocol

The fibre loop switch maintains signal and data integrity by re-timing and re-amplifying the signal at each port. The data-path routing, however, is significantly different in the switch than with a hub.

As shown on the top of Figure 3, a Fibre Channel network has a physical loop structure. All traffic must go through all nodes. Since the physical media is shared by all nodes, the bandwidth must be partitioned between any nodes that

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