Re: iSCSI:Problem with use of NotUnderstood in negotiations

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

The (valid) point that Pat was making is that we do not request the receiver to check for every protocol error and it would
be advisable to say something about a "blanket" protection.

I have proposed a text for this in my previous note.
Again neither this nor the protocol errors are mandatory - but  a wise
implementer will do something.

Thanks,
Julo

John Hufferd@IBMUS 08/13/2002 09:13 AM

To:        Julian Satran/Haifa/IBM@IBMIL@IBMDE         cc:        ips@ece.cmu.edu         From:        John Hufferd/San Jose/IBM@IBMUS         Subject:        iSCSI:Problem with use of NotUnderstood in negotiationsLink

Isn't there a way to say that if you get a response of NotUnderstood, to a key that you do not understand, or to a key that you did not offer, that it is a protocol error.  That should stop the loop dead in its tracts.  It could be stated on page 66.

The Pseudo Code would be,....do I understand the key, if not .... is NotUnderstood its value ... if so protocol error!   (clearly if I do not understand it, I did not offer it.)

.
.
.
John L. Hufferd
Senior Technical Staff Member (STSM)
IBM/SSG San Jose Ca
Main Office (408) 256-0403, Tie: 276-0403,  eFax: (408) 904-4688
Home Office (408) 997-6136, Cell: (408) 499-9702
Internet address: hufferd@us.ibm.com

Sent by:        owner-ips@ece.cmu.edu

To:        Julian Satran/Haifa/IBM@IBMIL, ips@ece.cmu.edu
cc:        
Subject:        RE: Problem with use of NotUnderstood in negotiations



Julian,

In the scenario, each device does use Notunderstood in a response.

A sends keyxxx
Silent data corruption occurs that changes keyxxx to keyxxy
B gets keyxxy and doesn't recognize it so it responds
keyxxy=Notunderstood
A gets that and thinks it is an offer of a key it doesn't understand because it never sent keyxxy.
A therefore sends
keyxxy=Notunderstood
B gets keyxxy and doesn't recognize it so it responds
keyxxy=Notunderstood
.....

Regards,
Pat

-----Original Message-----
From: Julian Satran [mailto:Julian_Satran@il.ibm.com]
Sent: Friday, August 09, 2002 9:24 PM
To: ips@ece.cmu.edu
Subject: RE: Problem with use of NotUnderstood in negotiations



Bill,

Perhaps the text is unabiguos but you just ignored the text that forbids
it.
The use of Notunderstood is limited to responses. Using it as you suggest
is a protocol error.
A repeated use will also violate the "no renegotiation rule".

Julo





Bill Studenmund
<wrstuden@wasabis        To:       Bart Crane <bcrane@iready.com>
ystems.com>              cc:       <ips@ece.cmu.edu>
Sent by:                 Subject:  RE: Problem with use of NotUnderstood in negotiations
owner-ips@ece.cmu
.edu


08/10/2002 02:22
AM





On Fri, 9 Aug 2002, Bart Crane wrote:

?? In the scenario I describe, neither side believes it offered the key.

> Thus, there is no need to add another rule regarding not-responding to
> keys with NotUnderstood as a value, because a key with that value is
> a protocol error.
>
> This could be made more explicit, but there does not seem to be any
> ambiguity.

There obviously is ambiguity. The fact we're having this discussion is
proof. :-)

I'd support saying this case is a protocol error, since it means something
neither side understands got into the stream (and chances are an offer got
removed). But I think adding an explicit direction as to what to do is
needed.

Take care,

Bill