Sequence Count Value and SRR
Carl.Zeitler at COMPAQ.com
Thu Jun 15 06:29:28 PDT 2000
* From the T10 Reflector (t10 at t10.org), posted by:
* "Zeitler, Carl" <Carl.Zeitler at compaq.com>
At the last meeting there was much discussion on Sequence Count and what
values were used in retransmission. For the current definition, a Sequence
Count of 0 is required. For future error recovery in Class 2, out-of-order,
it would be desirable to use increasing Sequence Count to reduce error
I believe there is a simple solution.
Define a bit (Word 3, Bit 9?) in the FCP service parameter page, PRLI
request as follows.
Give the bit a name: Sequence Count Usage (?)
If the Sequence Count Usage Bit is 0, then the recipient of SRR shall
retransmit Data Frames starting with a Sequence Count of 0.
If the Sequence Count Usage Bit is 1, then the recipient of SRR shall
retransmit Data Frames starting with the next consecutive value of the
With this added bit, current recovery can use continuously increasing
sequence count and yet not have to remember the last used value. If faster
error recovery for out-of-order is desirable in Class 2 in the future, then
this can be negotiated between Initiator and Target during PRLI.
Compaq Computer Corporation
MS 150801, 20555 SH249, Houston, TX 77070
Phone:281-518-5258 Fax: 281-514-5270
E-Mail: Carl.Zeitler at compaq.com
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