Re: [iSCSI]: Key negotiation procedure proposal

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

Discovering capabilities is best left to discovery (SLP, iSNS etc.).
Reject, Irrelevant etc., should be marginal and IMHO are here to handle gracefully exceptions.
I would not complicate negotiation beyond a one time handshake - except perhaps for deep negotiation trees 
if they can be proven useful. And even then I would leave them for iSCSI-2  :-)

Julo

Luben Tuikov <luben@splentec.com> Sent by: luben@ns.splentec.com 05/23/2002 04:35 PM Please respond to Luben Tuikov

To:        iSCSI <ips@ece.cmu.edu>, Julian Satran/Haifa/IBM@IBMIL         cc:                 Subject:        [iSCSI]: Key negotiation procedure proposal

I'm proposing the following key negotiation procedure. It
preserves the no-renegotiation of keys rule and all the
rules of login request and response currently used in the
draft (12-91). It applies to any kind of value (list,
boolean, integer, etc.).

Simple implementations:

Simple implementations SHOULD close the connection right
after Reject has been communicated. This ensures that the
reason for closing has been communicated to the peer.

Regular implementations:

Core rule: A negotiation of a key=value pair is
complete/finished when both the Originator and Responder
have sent their values (non-reserved keywords).

The core rule implies the the following:

If a Responder replies with Reject, then the Originator
SHOULD NOT renegotiate the rejected key.

If a Responder replies with Reject, it SHOULD sent its value
of that key on the next reply to the Originator.

If an Originator finds the response to an offered key=value
pair to be unacceptable, it SHOULD send Reject and close the
connection.

Please note that the core rule above ensures that both the
Originator and Responder _know_ each other's values if the
connection is closed due to Reject. This will give the user
of each node more information to find out what went wrong.
That is, this kind of negotiation is exhaustive.

Let O: denote Originator and R: the Responder.

Example 1:
----------
O: v = x  -->
         <--   R: v = Reject

O: ""     -->
         <--   R: v = y

O: 1) v = y is OK, continue as normal,
   2) v = y is unacceptable,
   
   v = Reject -->
   close the connection (reason just given).


Example 2:
----------
O: v = x  --> 
         <--   R: v = y

O: 1) v = y is OK, continue, as normal,

   2) v = y is unacceptable,
   
   v = Reject -->

   close the connection (reason just given).

-- 
Luben