FCP-2 problem

Neil T. Wanamaker ntw at crossroads.com
Wed Jun 14 13:13:24 PDT 2000

* From the T10 Reflector (t10 at t10.org), posted by:
* "Neil T. Wanamaker" <ntw at crossroads.com>
At 02:57 PM 6/14/00 -0400, Terence Kelleher wrote:
>* From the fc reflector, posted by:
>* "Terence Kelleher" <terryk at pathlight.com>
>Does use of FCP_CONF_REQ on the response resolve the issue? The target will
>release the resource after receiving FCP_CONF and the OXID is free. The REC
>sent after the lost command will then not receive an ACC, as the OXID is
>CMD OXID = 1 ----->
>                <----- FCP_RSP with FCP_CONF_REQ
>FCP_CONF     ----->
>CMD OXID = 1 ---X
>REC          ----->
>                <----- LS_REJ
>If the FCP_CONF is lost, the target would issue REC to request
>retransmission. If the OXID is reused before FCP_CONF is delivered to the
>target, the Command is rejected because the OXID refers to an exchange which
>is still open.

The use of FCP_CONF will make things better, in that there will not be an 

As long as messages must be passed between initiator and target, there are 
windows during which the two are in different states. With FCP_CONF, the 
exchange can be closed first by the target (as in FCP(-1)). Even if the 
initiator closes the exchange before receiving confirmation that the target 
has received the FCP_CONF (and the initiator re-uses the OX_ID), the 
behavior is benign, because the target can reject the new command if the 
FCP_CONF was lost; the initiator can then reissue the command with a new 
OX_ID, the target can age out the old exchange, and everybody's happy.

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