DDIS bit

Bob Snively Bob.Snively at Ebay.Sun.COM
Mon Nov 9 14:38:50 PST 1998


* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* Bob Snively <Bob.Snively at Ebay.Sun.COM>
*

In control mode page 19 for Fibre Channel, the DDIS bit presently is 
described in the following manner:

A Disable Discovery (DDIS) bit of one indicates that a target 
attached to an FC-AL loop shall not require receipt of Address 
or Port Discovery (ADISC or PDISC ELSs) following loop initialization. 
The logical units shall resume processing tasks on completion of 
loop initialization. When the DDIS bit is zero, the target shall 
wait to complete target discovery as defined by FC-PLDA and FC-FLA 
before allowing processing of tasks to resume. Targets attached to 
an N_Port or to an F_Port shall ignore this bit.

It was proposed at the SCSI meeting that PLOGI be included in this list.

As recently as April, this was not part of the documented behavior of
DDIS and I believe it should not be part of the behavior.  Basically, if
a device has done an implicit LOGOUT, the presence of a DDIS bit should
not prevent its soliciting a PLOGI with an appropriate response.  PLDA
already indicates that a device is not required to generate a PLOGI
under any conditions.

For consistency with the previous documents, I have elected to leave 
the PLOGI out of the list of ELSs disabled by DDIS in spite of the
informal request in the committee meeting. Let me know what you think 
about that decision.

Bob

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