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parameter allows the host to specify that the peripheral device addressing method will be used regardless
of the Addressing Method field in the first level address. This allows custom address translations to be
built for systems that may not properly support hierarchical addressing.
Virtual Device Addressing Method
15
14
13
12
0
1
The LUN field indicates the address of the device to which the command will be routed. The FibreBridge
will extract the Bus Number, Target and LUN fields from the LUN based upon parameters contained in
FibreBridge non-volatile RAM. The default configuration imposes the following definitions on the LUN
field. The SAM-2 specification leaves this to be too arbitrary so again, the FibreBridge default settings
are as listed below.
15
14
13
12
0
1
N/A
Again, the location and width of the Bus, Target and LUN fields are field programmable and are stored in
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.
Logical Unit Addressing Method
15
14
13
12
1
0
The Logical unit address method behaves exactly as the Peripheral device address method with two
notable exceptions – field placement and width. The Bus number and Target fields have been moved.
The LUN and Target fields are larger and the Bus number field is smaller. The FibreBridge will decode
logical unit addressing as described in the peripheral device address method section. Just as with the
peripheral and virtual modes, the location and width of the Bus, Target and LUN fields are field
programmable.
The default mode for Logical Addressing is the same as defined in the SAM-2
specification.
FibreBridge Default Mode
By default, the FibreBridge suppresses the above methods of Hierarchical Addressing and uses its own
method, which closely follows the rules of peripheral addressing. This method of addressing is in effect
regardless of the Address Method field in the first level address unless you select the option to perform
LUN translations.
15
14
13
12
0
0
Bit Number
11
10
9
8
Bit Number
11
10
9
8
LUN
Bit Number
11
10
9
8
Target
Bit Number
11
10
9
8
N/A
ATTO Technology, Inc.
ATTO FibreBridge Installation & Operation Manual
7
6
5
4
LUN
7
6
5
4
Target
7
6
5
4
Bus Number
7
6
5
4
LUN
- 40 -
3
2
1
0
3
2
1
0
Bus Identifier
3
2
1
0
LUN
3
2
1
Target
Bus
0
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