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posted Dec 8, 2013, 11:52 AM by Rick McGee   [ updated Dec 9, 2013, 5:43 PM ]
What is iSCSI
  • Internet Small Computer System Interface (iSCSI)
    • SCSI over TCP over IP
  • Completely separate protocol stack form Fibre Channel
  • Typically used in small to mid-range SAN's
    • No dedicated SAN switches required
    • No SAN switching knowledge required
  • 1/10GE iSCI hardware offload cards available 
iSCSI and the CCIE DC Test/Lab
  • iSCSI is not SAN switching
    • End hosts run IP
    • Storage Array runs just IP
    • Transport is anything IP
  • MDS can be used as an iSCSI to FC gateway
  • MDS is effectively a translational bridge for Fibre Channel and iSCSI
    • Think bridging between Ethernet and Frame Relay in IOS
  • How iSCSI gateway work
    • FC Targets FLOGI as usual to Fibre Channel Fabric
    • iSCI Initiators send Discovery to MDS
      • Implies MDS has IP enabled Ethernet interfaces
    • MDS applies Zoning/Access Lists
    • iSCSI Initiator thinks FC target is iSCSI Target
    • FC Target thinks iSCSI Initiator is FC Initiator
iSCSI Access Control
  • Like in FC, access control must be enforced
    • Mounting someone else's volue can be catastrophic
  • Access control can be enforced as:
    • Zoning Based
      • Norman WWPN, FCID, and Aliases, etc...
      • Initiator's IP address
      • Initiator's iSCSI qualified name (IQN)
    • iSCSI Based Virtual Target
      • IQN
      • IP address and Subnet
What s FCIP
  • Fibre Channel over IP (FCIP)
    • SCSI over FCP over TCP over IP
  • Same protocol stack as Fibre Channel
    • Think IPv6 over IPv4 GRE tunnel
    • Initiators and Targets are still Native Fibre Channel (of FCOE)
  • Used for Fibre Channel SAN Extension
    • Data replication over long distance
    • Native Fibre Channel is sensitive to latency and drops
    • TCP already has built in congestion management, retransmission, etc.
Here is a good diagram that shows the difference SAN protocol stack