ADC-2: Topology Auto configuration

[Kevin D Butt]

Michael,

Thanks for the response.  I will provide a proposal for adding a new bit to select between LN-Port and NL-Port when TOPLOCK is set to zero.  The zero value of the bit will be LN-Port since that is the standard defined method that I believe most use.

Thanks,

Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-2869 / 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at us.ibm.com
http://www-03.ibm.com/servers/storage/


"Banther, Michael" <michael.banther at hp.com>
Sent by: owner-t10 at t10.org

03/29/2006 06:25 AM
To
Kevin D Butt/Tucson/IBM at IBMUS, <t10 at t10.org>
cc
Subject
RE: ADC-2: Topology Auto configuration




Hi Kevin,

Given that not all device ports support NL-Port operation, I'd prefer to see you propose using a new bit.  That way devices that do not support the feature can return CHECK CONDITION for an Invalid Field in CDB and easily point to the new bit.

Regards,
Michael Banther
Hewlett-Packard Ltd.
Telephone +44 (117) 312-9503


From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Kevin D Butt
Sent: 27 March 2006 22:15
To: t10 at t10.org
Subject: ADC-2: Topology Auto configuration


ADC WG,

In ADC-2, 6.2.2.3.3 Fibre Channel descriptor parameter format, there is defined the topology lock bit.
<<<
A topology lock (TOPLOCK) bit set to one forces the DT device primary port to operate only in the mode selected by
the P2P bit. A TOPLOCK bit set to zero indicates the DT device primary port may negotiate the topology (see FC-FS).
If the TOPLOCK bit is set to zero in a MODE SELECT command (see SPC-3), the P2P bit shall be ignored.

A point-to-point (P2P) bit set to one indicates the DT device primary port is configured to operate in point-to-point
mode. If the P2P bit is set to one and the TOPLOCK bit is set to one, the RHA bit, LIV bit, and FC-AL LOOP ID field shall
be ignored in a MODE SELECT command. A P2P bit set to zero indicates the DT device primary port is configured
to operate in arbitrated loop mode.
>>>

IBM drives have had the option since FC2G devices were implemented, to select configurations of N-Port, L-Port, LN-Port, and NL-Port in our terminology.  That is, 1) N-Port (force Fabric Topology), 2) L-Port (Force Arbitrated Loop), 3) LN-Port (Auto-Configure tryin L-Port or Arbitrated Loop first), and 4) NL-Port, (Auto-Configure trying N-Port or Fabric Topology first).  There is no way in the ADC to distinuguish between LN-Port and NL-Port.

It is IBM's desire to add the capability to distinguish between LN-Port and NL-Port to ADC-2.  If FC-AL-2 is strictly followed, a device will attempt FC-AL and then, if unsuccessful, fall into OLD_PORT state (i.e. port operating as an N-Port).  This would match our LN-Port.  However, it is not known that all current implementations interpret the settings this way.

The are two possible solutions that I am contemplating proposing:
1) Use the P2P bit when the TOPLOCK bit is set to zero.  If P2P is set to one use NL-Port, if P2P is set to zero then use LN-Port.
2) Use a new bit from the reserved bits to indicate NL-Port.

Any comments?

Thanks,

Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-2869 / 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at us.ibm.com
http://www-03.ibm.com/servers/storage/