Specifications

13 ATTO Technology FibreBridge 4500 Installation and Operation Manual
3.1 ATTO FibreBridge addressing
The ATTO FibreBridge allows parallel SCSI devices to participate in a Fibre Channel arbitrated loop
or on a fabric. Fibre Channel and parallel SCSI use different models to address devices. The
FibreBridge translates between these addressing models.
The chart below is a simplified overview of data
and control flow between the application and the
SCSI device through a number of stages.
Fibre Channel World Wide Name (WWN)
Each Fibre Channel device is assigned a unique
World Wide Name (WWN). The WWN is used to
identify all Fibre Channel devices. The 64-bit
WWN has the following format:
The Institute of Electrical and Electronics
Engineers (IEEE) assigns each manufacturer a
unique Company ID. The Device ID field
contains a unique value assigned by ATTO
Technology to every Fibre Channel product
produced by ATTO Technology.
Arbitrated Loop Port Address (AL_PA)
On a Fibre Channel Arbitrated Loop, the
FibreBridge appears at a single Arbitrated Loop
Port Address (AL_PA). Each device on an
arbitrated loop is assigned a unique AL_PA
during loop initialization. The FibreBridge
supports both modes of AL_PA assignment,
commonly referred to as hard and soft addressing .
Soft addressing allows the loop initialization
master to assign the FibreBridge a unique AL_PA
during the loop initialization process. The AL_PA
assigned cannot be determined before loop
initialization. For example, adding new devices to
an arbitrated loop may change the AL_PA
assigned to the FibreBridge.
Hard addressing allows a predetermined AL_PA
to be assigned to the FibreBridge. The
FibreBridge will try to acquire the desired hard
AL_PA. If another device has already been
assigned the specified AL_PA, the FibreBridge
will acquire a currently unassigned AL_PA.
ATTO BridgeTools software allows you to select
either hard or soft addressing modes. The default
mode is soft addressing.
Addressing devices
SCSI devices connected to the FibreBridge also
show up as Fibre Channel LUNs to the host
computer. SCSI devices must be on the same
addressing level as the SCSI portion of the
FibreBridge. The FibreBridge SCSI ports must be
set to different SCSI IDs than the devices on the
bus.
Application
Read & write data
Operation
System
SCSI LUN addressing in OS native form
.
Host Bus
Adapter
Maps OS native LUNs
FCP
(SCSI)
FCP_CMD: LUN plus CDB plus data
FibreBridge
Parse Fibre port and Fibre LUN into SCSI
BUS:Target:LUN
SCSI bus
Transport SCSI address, CDB and data
to/from SCSI device
SCSI
device
SCSI device operation
Field
Name
WWN
Format
Company ID Device ID
Byte 01234 567
Value 2000001086 xxxxxx