Re: iSCSI: Sequence Reception TimeOut for Response PDUs

["Julian Satran" <Julian_Satran@il.ibm.com>]

To clarify the intent of 6.12.1 we may want to make the text of clause b) at the  initiator:

Sequence reception timeout (no status) or response reception timeout - dealt with as specified in Section 6.6 Sequence Errors, using the option of a SNACK.

The added words are "or response reception timeout". 

Julo
----- Forwarded by Julian Satran/Haifa/IBM on 06/30/2002 04:03 PM -----

Julian Satran 06/29/2002 04:38 PM

To:        "Praveen Kumar" <praveen@basilnet.com>         cc:        ips@ece.cmu.edu         From:        Julian Satran/Haifa/IBM@IBMIL         Subject:        Re: iSCSI: Sequence Reception TimeOut for Response PDUs

Praveen,

Looking at the text again before putting it I think It would be better we leave things as they are and here are the reasons:

1. Outstanding statuses/responses (i.e., those about which both initiator and target know) is handled in 6.12.1 and it includes timeout at both initiator and target
2. The above leaves for 6.12.2 mainly those cases that are not known to both parties (one way messages) and those are best handled by the party that knows about them - and is covered by 6.12.2 target action on unacked statuses. The initiator may use a periodic NOP (as we say somewhere else) but the target should be left to worry about statuses about which the initiator does not know about.
   
   
   So my latest suggestion is - LEAVE THINGS AS THEY ARE.
   
   Sorry for the confusion I may have created.
   
   Julo
   ----- Forwarded by Julian Satran/Haifa/IBM on 06/29/2002 04:24 PM -----
   

   Julian Satran 06/29/2002 12:27 PM

   To:        "Praveen Kumar" <praveen@basilnet.com>         cc:        ips@ece.cmu.edu         From:        Julian Satran/Haifa/IBM@IBMIL         Subject:        Re: iSCSI: Sequence Reception TimeOut for Response PDUsLink

   
   
   Praveen,
   
   I intend to add to 6.12.2 the following text:
   
   - An initiator may also recognize a lost iSCSI numbered response by an iSCSI timeout. In this case, error handling is done as specified in Section 6.6 Sequence Errors, using the option of a SNACK. However since SCSI command response is highly command dependent the SNACK may result in a Reject with an "invalid PDU field" reason code if the response was not issued.
   That should solve the issue.
   
   Julo
   
   
   

   "Praveen Kumar" <praveen@basilnet.com> 06/26/2002 10:05 PM Please respond to "Praveen Kumar"

   To:        Julian Satran/Haifa/IBM@IBMIL         cc:                 Subject:        iSCSI: Sequence Reception TimeOut for Response PDUs

   
   
   Julian,
    
   In Section 6.12.2, under the Paragraph "-Lost iSCSI Numbered Response" , is there any reason for NOT including "Sequence Reception TimeOut" as one of the mechanisms for detecting a "Lost iSCSI Numbered Response"?
   If a Numbered iSCSI response PDU is dropped (owing to header digest errors) , the Initiator could TimeOut waiting for the appropriate StatSN (assuming that the target implementation does Not support the issue of Nop-In, when Status is Not acknowledged for a long time).
   Section 6.12.1 does mention this, but that section only deals with Lost Data or R2T PDUs, NOT Lost Response PDUs.
   I would have expected this section (6.12.2) to mention this (Sequence Reception TimeOut) as a possibility (especially since the other sections explicitly mention this).
    
   Thanks in Advance
   Praveen