text: No more than three ISL hops are permitted among nodes that are in the same system though 
  in different I/O groups. If your configuration requires more than three ISL hops for nodes that 
  are in the same system but in different I/O groups, contact your support center. 
  
  Avoid ISL on the path between nodes and back-end storage. If possible, connect all storage 
  systems to the same Fibre Channel or FCF switches as the nodes. One ISL hop between the 
  nodes and the storage systems is permitted. If your configuration requires more than one ISL, 
  contact your support center. 
  
  In larger configurations, it is common to have ISLs between host systems and the nodes. 
  
  To verify the supported connection speed for FC links to the Storwize V7000, use the hIBM 
  System Storage Interoperation Center (SSIC) website. 
  
  For more information about the configuration of Enhanced Stretched Cluster or HyperSwap 
  setup, see IBM System Storage SAN Volume Controller and Storwize V7000 Best Practices 
  and Performance Guidelines, SG24-7521. 
  
  **3.6.2 Zoning**
  
  In Storwize V7000 deployments, the SAN fabric must have two distinct zone classes: 
  
  (cid:2) Host zones: Allows communication between Storwize V7000Storwize V7000 and hosts. 
  (cid:2) Storage zone: Allows communication between Storwize V7000 and back-end storage. 