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ATTO Technology, Inc. ATTO FibreBridge Installation & Operation Manual
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ATTO Technology, Inc.
Bit Number
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Address
Method
Address Method Specific Definition
Bits 15-14 contain the Address Method code. This code is used to determine how the remaining 14 bits
are to be interpreted by SCSI devices. The following table defines the available Addressing Methods.
Address Method Code
Description
00b Peripheral device addressing method
01b Virtual device addressing method
10b Logical unit addressing method
11b
RESERVED
An overview of the three defined Addressing Methods is given below. The fields are listed as defined in
the SAM-2 specification. Details of each Addressing Method are discussed later in this document.
These Address Methods provide alternative user definable paths to SCSI devices. The Peripheral Device
Addressing Method (PDAM) is the predominant method and is what is used in the examples that follow.
Since by definition, bits 15-14 are 00, it is the only method that can be used by host/environments
supporting <16 bits of LUN addressing. If the host/environment can support 16 bits, then any of the 3
addressing methods can apply.
Peripheral Device Addressing Method
Bit Number
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0 0 Bus Identifier Target / LUN
By definition, PDAM address 0 (bus = target = LUN = 0) selects the FibreBridge.
The Target field identifies the SCSI ID of the addressed SCSI device. The LUN field will select the logical
unit in the addressed target. Since the SCSI Architectural Model – 2 (SAM-2) does not specify exactly
which bits are assigned to the Target and which bits to the LUN, the FibreBridge makes this user
definable. The default assignments are listed below.
Bit Number
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0 0 N/A Bus Identifier Target LUN
The location and width of the Bus, Target and LUN fields are field programmable and are stored in the
FibreBridge non-volatile RAM. This allows custom address translations to be created to meet special
requirements for the customer, operating system, host bus adapter or peripheral device. Another NVRAM