HP Mainframe Connectivity Design Guide

Level 3: single resilient fabric with multiple device paths
Level 3 is the same as level 2, but provides multiple mainframe and storage system ports to the
fabric to increase availability . If a FICON director port, mainframe channel, or storage system
port failure occurs, data is automatically rerouted through an alternate path and there is no
interruption in mainframe I/O activity. Figure 6 (page 22) shows a level 3 fabric.
To take full advantage of level 3, HP recommends that you connect the mainframe channels and
storage system ports to different directors in the fabric to increase availability and reduce the
potential for a SPOF. This level provides both fabric resiliency and device path redundancy.
Figure 6 Level 3: single resilient fabric with multiple device paths
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22 FICON SAN fabric topologies