RE: iSCSI - revised 2.2.4

["Sanjeev Bhagat (TRIPACE/Zoetermeer)" <sbhagat@tripace.com>]

Julian,

 

I would also request an explicit definition of offering party and responding party. The current text still leaves ambiguity when target sends a key in response to implicit default key of the Intiator. In this case who is the offering party and who is the responding party

 

Sanjeev

-----Original Message-----
From: Julian Satran [mailto:Julian_Satran@il.ibm.com]
Sent: Friday, October 05, 2001 2:06 PM
To: ips@ece.cmu.edu
Subject: iSCSI - revised 2.2.4

Here is a revised (complete) part 2.2.4 based on recent agreed changes:

1.1.1        Text Mode Negotiation

During login and thereafter some session or connection parameters are negotiated through an exchange of textual information.

All negotiations are stateless - i.e. the result MUST be based only on newly exchanged values.

The general format of text negotiation is:

Originator-> <key>=<valuex>
Responder-> <key>=<valuey>|reject|NotUnderstood

The value can be a number, a single literal constant a Boolean value (yes or no) or a list of comma separated literal constant values.

In literal list negotiation, the originator sends for each key a list of options (literal constants which may include "none") in its order of preference.

The responding party answers with the first value from the list it supports and is allowed to use for the specific originator.

The constant "none" MUST always be used to indicate a missing function. However, none is a valid selection only if it is explicitly offered.

If a target is not supporting, or not allowed to use with a specific originator, any of the offered options, it may use the constant "reject".  The constants "none" and "reject" are reserved and must be used only as described here.  Any key not understood is answered with "NotUnderstood".

For numerical and single literal negotiations, the responding party MUST respond with the required key and the value it selects, based on the selection rule specific to the key, becomes the negotiation result.  Selection of a value not admissible under the selection rules is considered a protocol error and handled accordingly.

For Boolean negotiations (keys taking the values yes or no), the responding party MUST respond with the required key and the result of the negotiation when the received value does not determine that result by itself.  The last value transmitted becomes the negotiation result.  The rules for selecting the value to respond with are expressed as Boolean functions of the value received and the value that the responding party would select in the absence of knowledge of the received value.
 
Specifically, the two cases in which responses are OPTIONAL are:

- The Boolean function is "AND" and the value "no" is received. The outcome of the negotiation is "no".
- The Boolean function is "OR" and the value "yes" is received. The outcome of the negotiation is "yes".

Responses are REQUIRED in all other cases, and the value chosen and sent by the responder becomes the outcome of the negotiation.

The value "?" with any key has the meaning of enquiry and should be answered with the current value or "NotUnderstood".

The target may offer key=value pairs of its own. Target requests are not limited to matching key=value pairs as offered by the initiator.  However, only the initiator can initiate the negotiation start (through the first Text request) and completion (by setting to 1 and keeping to 1 the F bit in a Text request).


Comments ?

Julo