e1200-320 4Gb Fibre Channel Interface Card user and service guide 113
D Addressing, structures, and operations
Fibre Channel and SCSI systems employ different methods of addressing devices. The inclusion of a
interface card requires that a method of translating device IDs be implemented so that each SCSI device is
mapped to the appropriate Fibre Channel LUN. The SCSI buses establish bus connections between
devices. Targets on a SCSI bus may internally address logical units. The addressing of a specific SCSI
device is represented by the BUS:TARGET:LUN triplet.
When a Fibre Channel initiator initializes on a loop, the host must first determine what devices exist on
the loop. Device discovery is performed, and an FCP target device list is built. Each device is queried for
FCP logical units. The logical units are the actual devices that the operating system will address. When an
initiator addresses a logical unit, the LUN field used is consistent in form with the SCC defined fields. All
current Fibre Channel host bus adapter drivers are consistent with these methods. The addressing used is
the SCC Logical Unit Addressing and Peripheral Device Addressing methods, shown in Table 17 and
Table 18. First level addressing is supported, so only the first 2 bytes of the 8-byte FCP LUN are used.
Table 17 SCC addressing structure
Table 18 Address method definitions
Table 19 SCC logical unit addressing
Table 20 Peripheral device addressing
Bit
Byte
7654321 0
N Address Method Address Method Specific
N+1 Address Method Specific
Codes Description
00 Peripheral Device Addressing Method
01 Volume Set Addressing Method
10 Logical Unit Addressing Method
11 Reserved
Bit
Byte
7654321 0
N10 Target
N+1 Bus LUN
Bit
Byte
7654321 0
N00 Bus
N+1 Target/LUN
