Description: This MIB instrumentation is for managing Fibre
     Channel (FC) SAN Device Virtualization (SDV) 
     solution on Cisco Fibre Channel devices.
     
Glossary of the terms used in this MIB:
---------------------------------------
Config Commit  - User initiated action that triggers
                 commiting of configuration to local
                 device/fabric. Eg. CFS based config 
                 'commit' as described in CISCO-CFS-MIB.
                 
Domain         - The highest or most significant 
                 hierarchical level in the three-level
                 FC addressing hierarchy.
                 
Device Aias    - is a string which can be used to alias a
     World Wide Name (WWN).
                 
FCID           - Fibre Channel Address ID. A 24 bit Fabric
                 unique address identifier.
                 
FCNS           - Fibre Channel Name Server.
                 
Initiator      - The system component that originates an
                 I/O command over an I/O bus or network.
                 
NWWN           - WWN associated with FC node.
                 
PWWN           - WWN associated with FC port.

Real Device    - A hardware entity which includes Link
                 Control facility. It is directly
                 connected to a FC fabric and acts as
                 originator/responder or both.
                 
RSCN           - Registered State Change Notification.
                 RSCN Notifications are sent to Nx_ports
                 and other switches to notify that an
                 event has occurred.
                 
SW_RSCN        - Switch Registered State Change
                 Notification. SW_RSCN Notifications are
                 sent to neighbouring switches in a
                 fabric to notify that an event has
                 occurred.
                 
SCSI           - Acronym for Small Computer System
                 Interface.
                 
Target         - The system component that receives a
                 SCSI I/O command command.
                 
Virtual Device - The virtual initiator/target having its
   (VD)          own device identity and proxies a Real
                 Device (Initiator/Target) in a FC fabric.

VT             - Virtual Target.   

VI             - Virtual Initiator.

Virtual Domain - A logical Domain partition in a FC fabric
                 within which a Virtual Device exists.            
                             
VSAN           - Virtual Storage Area Network, similar
                 to a VLAN.

WWN            - Wide Name (WWN) associated with
                 a Fibre Channel (FC) entity. A 64 bit
                 identifier, with a 60 bit value preceded
                 with a four bit 
                 Network_Address_Authority_Identifier,
                 used to identify physical entities in
                 Fibre Channel.
      
     The primary motivation for SAN Device Virtualization
     is the High availability of storage disk arrays with
     no downtime. Redundancy is achieved by duplication
     of information and hardware to ensure secondary
     device can take over the function of a primary
     device when the latter fails. The initiators
     (servers) perform I/O to the primary target. 
     The secondary target is kept in sync to have a
     mirrored copy of the primary target by a replication
     mechanism. In the event of a disruption to primary
     target, all I/O must be immediately re-routed to 
     secondary target so that services running on 
     initiators remain un-interrupted. The SDV solution
     resides on a Cisco FC Switching Device. The target 
     failover is achieved by presenting a virtual proxy
     target to initiator with the SDV acting as a conduit
     for creating and deleting the proxy (virtual)
     target on demand. The Virtual Target or in general
     Virtual Device can virtualize (proxy) set of Real
     Devices with one Real Device actively mapped as the
     primary mapping and the rest as secondary mappings.
    
                                       WWN2,FCID2
                                        _____
                                       |     |
                  [Switch Fabric]     /| RT1 |
                  '''''''''''''''    / |_____|
    WWN1,FCID1    '             '   /  [Primary Real
       ____       '  WWN4,FCID4 '  /    Target Device]
      |    |      '  +~~~~~~~+__'_/ 
      | I  |->--->'->|  VT   |__'_
      |____|      '  +~~~~~~~+  ' \     
     [Real Host   '             '  \{On Fail-Over}
     (Initiator)] '             '   \   WWN3,FCID3
                  '''''''''''''''    \  _____
                 [VT: Virtual Target] \|     |
                                       | RT2 |
                                       |_____|
                                       [Secondary Real
                                        Target Device]
                                        
                   -<< Fig 1 >>-

     In the above figure (Fig 1), 'Switch Fabric'
     presents the Virtual Target 'VT' as a proxy device
     for real targets 'RT1' and 'RT2'. The Host/Initiator
     'I' can discover a virtual target VT and does not
     see real targets RT1 and RT2 as accessible targets.
     The Virtual Target VT is configured on the switch
     and maps to one real target as a primary mapping.
     The Initiator performs I/O with VT. When the primary 
     target RT1 fails, the secondary real target RT2 can
     take over. For the Initiator, failover/migration is
     transparent and continues to perform I/O with VT.

      ___                   ____                  ____
     |   |-->--[I->VT]-----[    ]---->--[I->T]---|    |
     | I |                 [ VT ]                | RT |
     |   |                 [    ]                |    |
     |___|--<--[I<-VT]-----[____]----<--[I<-T]---|____|

  [Initiator]             [Virtualized           [Real
                           Target]                Target]

                   -<< Fig 2 >>-

     When the Initiator 'I' performs I/O with VT, the
     SDV enabled switch performs FCID address translation
     to route FC frames to the real target RT (refer
     Fig 2). The I->VT frames are translated as I->T. 
     The T->I frames are translated as VT->I. The SDV
     manages VT so that other devices (in the same zone)
     perceive it as just another device in the fabric.
    
     The cFcSdvVirtDeviceTable is table of Virtual Devices.
     The cFcSdvVirtRealDevMapTable is a table of mapping
     elements.
     
     A Virtual Device is represented by a row in the
     cFcSdvVirtDeviceTable, and if its value of 
     cFcSdvVdRealDevMapList has the value of zero,
     then the Virtual Device is not currently mapped to
     any Real Devices. Otherwise, the Virtual Device is
     mapped to the set of Real Devices with each Real
     Device identified by the instance indentifier value
     of cFcSdvVirtRealDevMapIndex.