Return-Path: X-Sieve: cmu-sieve 2.0 Return-Path: Received: (from majordom@localhost) by ece.cmu.edu (8.11.0/8.10.2) id h3T67J023298 for ips-outgoing; Tue, 29 Apr 2003 02:07:19 -0400 (EDT) X-Authentication-Warning: ece.cmu.edu: majordom set sender to owner-ips@ece.cmu.edu using -f Received: from d12lmsgate-3.de.ibm.com (d12lmsgate-3.de.ibm.com [194.196.100.236]) by ece.cmu.edu (8.11.0/8.10.2) with ESMTP id h3T67Hb23291 for ; Tue, 29 Apr 2003 02:07:17 -0400 (EDT) Received: from d12relay02.de.ibm.com (d12relay02.de.ibm.com [9.165.215.23]) by d12lmsgate-3.de.ibm.com (8.12.9/8.12.8) with ESMTP id h3T67ACi019476; Tue, 29 Apr 2003 08:07:10 +0200 Received: from d10ml001.telaviv.ibm.com (d10ml001.telaviv.ibm.com [9.148.216.55]) by d12relay02.de.ibm.com (8.12.8/NCO/VER6.5) with ESMTP id h3T679Hj277934; Tue, 29 Apr 2003 08:07:09 +0200 In-Reply-To: <004401c30dfe$2dbb26c0$45a2f40f@rose.hp.com> To: "Mallikarjun C." Cc: ips@ece.cmu.edu Subject: Re: iSCSI: ISID RULE and Discovery sessions MIME-Version: 1.0 X-Mailer: Lotus Notes Release 6.0.1 February 07, 2003 From: "Julian Satran" Message-ID: Date: Tue, 29 Apr 2003 09:07:06 +0300 X-MIMETrack: Serialize by Router on D10ML001/10/M/IBM(Release 5.0.9a |January 7, 2002) at 29/04/2003 09:07:09, Serialize complete at 29/04/2003 09:07:09 Content-Type: multipart/alternative; boundary="=_alternative 001C5160C2256D17_=" Sender: owner-ips@ece.cmu.edu Precedence: bulk This is a multipart message in MIME format. --=_alternative 001C5160C2256D17_= Content-Type: text/plain; charset="US-ASCII" Mallikarjun, By discussing this further we create an issue where none exist (an all this for a mechanism that I KNEW will get to hunt us). On the long run no serious discovery will be based in the "discovery session" and if there will be sometime a second version we can drop it and use only the standardized alternatives (iSNS, SLP, Bluefin etc.). Meanwhile let the rules be as they are. There is no harm done if a discovery session is dropped if the same initiator connects the same target with the same ISID (the target recognizes itself as the same target!). Let sleeping dogs lie.. Julo "Mallikarjun C." Sent by: owner-ips@ece.cmu.edu 29/04/03 06:19 To cc Subject Re: iSCSI: ISID RULE and Discovery sessions ISID is there for reasons that do not have anything to do with ISID RULE. The rule only takes advantage of ISID to enforce I_T nexus uniqueness. As Julian and I said, a discovery session is just an iSCSI protocol-ism that simply isn't related to an I_T nexus. -- Mallikarjun Mallikarjun Chadalapaka Networked Storage Architecture Network Storage Solutions Hewlett-Packard MS 5668 Roseville CA 95747 cbm@rose.hp.com ----- Original Message ----- From: "mphaneen" To: "Mallikarjun C." ; "Julian Satran" Cc: Sent: Monday, April 28, 2003 7:16 PM Subject: Re: iSCSI: ISID RULE and Discovery sessions > Hi, > *If* ISID RULE does not apply to Discovery session, then > I believe, the ISID information is immaterial for the Discovery session. > And thus I propose, an ISID need not be generated for a Discovery > session at all. > > Regards > Phani > > Phaneendra. M > Member Technical Staff > HCL TECHNOLOGIES LTD. > Chennai, India. > Phone: +91 044 23728366 extn: 1135 > > Visit us at: > http://www.hcltech.com/san > > > ----- Original Message ----- > From: "Mallikarjun C." > To: "Julian Satran" > Cc: > Sent: Monday, April 28, 2003 11:16 PM > Subject: Re: iSCSI: ISID RULE and Discovery sessions > > > > Julian, > > > > >or another > > > discovery session with the same InitiatorName and Isid. > > > > This may be hard to specify and also to implement. The question that > comes > > up will be - to the same target network entity or to the same target node? > > There may be concurrent discovery sessions attached to just one specific > > TargetName as well within that network entity, and I presume we don't want > > to bring them down when a new entity-level discovery session is > instantiated. > > > > My preference is to just not apply the ISID RULE in any scope to the > > discovery sessions. There's no logical correctness issue in any case with > them. > > > > If we agree that it's the reasonable thing to do, it might be useful to > add > > the following text to 12.21 ("SessionType"), if doing so is possible > anymore..... > > (David? Or is it something that has to wait for getting in to the command > > ordering draft? ) > > > > "A discovery session is an iSCSI-level protocol construct and so is not > > an I_T nexus. The "ISID RULE" stated in section 3.4.3 is thus not > applicable > > to discovery sessions." > > > > Thanks. > > -- > > Mallikarjun > > > > Mallikarjun Chadalapaka > > Networked Storage Architecture > > Network Storage Solutions > > Hewlett-Packard MS 5668 > > Roseville CA 95747 > > cbm@rose.hp.com > > > > ----- Original Message ----- > > From: "Julian Satran" > > To: "Pittman, Joseph" > > Cc: ; ; "dl-iscsi-eng" > ; ; > > ; "Kalman Meth" ; > > Sent: Saturday, April 26, 2003 12:44 AM > > Subject: Re: iSCSI: ISID RULE and Discovery sessions > > > > > > > It is true that in the discovery session the initiator does not have to > > > specify a TargetName as the purpose of the discovery session was to > > > discover the targets. > > > As such the discovery session is technically a session with the "iSCSI > > > Node" and the only thing that can bring it down is logout or another > > > discovery session with the same InitiatorName and Isid. > > > > > > Regards, > > > Julo > > > > > > > > > > > > "Pittman, Joseph" > > > 25/04/03 21:08 > > > > > > To > > > Julian Satran/Haifa/IBM@IBMIL, Kalman Meth/Haifa/IBM@IBMIL, > > > , , , > > > > > > cc > > > "dl-iscsi-eng" > > > Subject > > > iSCSI: ISID RULE and Discovery sessions > > > > > > > > > > > > > > > > > > > > > iSCSI specification authors and experts, > > > My name is Joe Pittman, an engineering at Network Appliance. > > > My group has implemented an iSCSI target based on draft 20 > > > of the iSCSI specification. > > > During interoperability testing, we have encountered an initiator > > > (Cisco Linux initiator from SourceForge), whose implementers have > > > interpreted the ISID RULE differently from the NetApp target > > > implementation. I need an authoritative ruling on the applicability > > > of the ISID RULE for Discovery sessions. > > > The ISID RULE states the following (draft-ietf-ips-iscsi-20.txt, > > > section 3.4.3): > > > ISID RULE: Between a given iSCSI Initiator and iSCSI Target Portal > > > Group (SCSI target port), there can only be one session with a given > > > value for ISID that identifies the SCSI initiator port. > > > Consider the case where an initiator {InitiatorName X, ISID I} has > > > created a Discovery session to a target. Then, without terminating > > > this session via LOGOUT, the same initiator {X,I} creates a new > > > Normal session to the same target, at the same target portal. The > > > question is, should the target terminate the existing Discovery > > > session in order to enforce the ISID RULE? > > > Because there is no mention of Discovery sessions vs. Normal sessions > > > in the ISID RULE section, my interpretation of the specification > > > was that the existing Discovery session MUST be terminated. > > > > > > But one of the authors of the Cisco Linux initiator interpreted > > > the specification differently. Here is an excerpt from an e-mail > > > message describing his logic: > > > > Discovery sessions don't have TargetNames, and the implicit logout > > > > only occurs when the InitiatorName, ISID, and TargetName all match. > > > > It should thus be impossible for a normal session to logout a > > > > discovery session, since the TargetNames for the two sessions can > > > > never match. I think your target has a bug. > > > > > > > > Discovery sessions don't really connect to a particular iSCSI > > > > target. It's more a connection to the iSCSI Node as a whole. > > > > Normal sessions connect to particular iSCSI targets. This should > > > > keep the two session types from conflicting, even if the ISIDs > > > > are the same. > > > > > > So, will one of you authors rule on this disagreement? I am > > > eager to fix my bug, if my interpretation was in error. > > > One followup question: > > > Also, if the Cisco interpretation is correct, then does the ISID > > > rule apply to two Discovery sessions? That is, if the target > > > receives a second Discovery session while the first Discovery > > > session is still active, MUST the target terminate the first > > > Discovery session in order to enforce the ISID RULE? > > > > > > Thanks in advance for any help you can provide. > > > -- > > > Joe Pittman > > > jpittman@netapp.com > > > > > --=_alternative 001C5160C2256D17_= Content-Type: text/html; charset="US-ASCII"
Mallikarjun,

By discussing this further we create an issue where none exist (an all this for a mechanism that I KNEW will get to hunt us).
On the long run no serious discovery will be based in the "discovery session" and if there will be sometime a second version we can drop it and use only the standardized alternatives (iSNS, SLP, Bluefin etc.). Meanwhile let the rules be as they are. There is no harm done if a discovery session is dropped if the same initiator connects the same target with the same ISID (the target recognizes itself as the same target!).  

Let sleeping dogs lie..

Julo


"Mallikarjun C." <cbm@rose.hp.com>
Sent by: owner-ips@ece.cmu.edu

29/04/03 06:19

To
<ips@ece.cmu.edu>
cc
Subject
Re: iSCSI: ISID RULE and Discovery sessions





ISID is there for reasons that do not have anything
to do with ISID RULE.  The rule only takes advantage
of ISID to enforce I_T nexus uniqueness.  

As Julian and I said, a discovery session is just an
iSCSI protocol-ism that simply isn't related to an
I_T nexus.
--
Mallikarjun

Mallikarjun Chadalapaka
Networked Storage Architecture
Network Storage Solutions
Hewlett-Packard MS 5668
Roseville CA 95747
cbm@rose.hp.com


----- Original Message -----
From: "mphaneen" <mphaneen@npd.hcltech.com>
To: "Mallikarjun C." <cbm@rose.hp.com>; "Julian Satran" <Julian_Satran@il.ibm.com>
Cc: <ips@ece.cmu.edu>
Sent: Monday, April 28, 2003 7:16 PM
Subject: Re: iSCSI: ISID RULE and Discovery sessions


> Hi,
>     *If* ISID RULE does not apply to Discovery session, then
> I believe, the ISID information is immaterial for the Discovery session.
> And thus I propose, an ISID need not be generated for a Discovery
> session at all.
>
>     Regards
>     Phani
>
> Phaneendra. M
> Member Technical Staff
> HCL TECHNOLOGIES LTD.
> Chennai, India.
> Phone: +91 044 23728366 extn: 1135
>
> Visit us at:
> http://www.hcltech.com/san
>
>
> ----- Original Message -----
> From: "Mallikarjun C." <cbm@rose.hp.com>
> To: "Julian Satran" <Julian_Satran@il.ibm.com>
> Cc: <ips@ece.cmu.edu>
> Sent: Monday, April 28, 2003 11:16 PM
> Subject: Re: iSCSI: ISID RULE and Discovery sessions
>
>
> > Julian,
> >
> > >or another
> > > discovery session with the same InitiatorName and Isid.
> >
> > This may be hard to specify and also to implement.  The question that
> comes
> > up will be - to the same target network entity or to the same target node?
> > There may be concurrent discovery sessions attached to just one specific
> > TargetName as well within that network entity, and I presume we don't want
> > to bring them down when a new entity-level discovery session is
> instantiated.
> >
> > My preference is to just not apply the ISID RULE in any scope to the
> > discovery sessions.  There's no logical correctness issue in any case with
> them.
> >
> > If we agree that it's the reasonable thing to do, it might be useful to
> add
> > the following text to 12.21 ("SessionType"), if doing so is possible
> anymore.....
> > (David?  Or is it something that has to wait for getting in to the command
> > ordering draft? )
> >
> > "A discovery session is an iSCSI-level protocol construct and so is not
> >  an I_T nexus.  The "ISID RULE" stated in section 3.4.3 is thus not
> applicable
> >  to discovery sessions."
> >
> > Thanks.
> > --
> > Mallikarjun
> >
> > Mallikarjun Chadalapaka
> > Networked Storage Architecture
> > Network Storage Solutions
> > Hewlett-Packard MS 5668
> > Roseville CA 95747
> > cbm@rose.hp.com
> >
> > ----- Original Message -----
> > From: "Julian Satran" <Julian_Satran@il.ibm.com>
> > To: "Pittman, Joseph" <Joseph.Pittman@netapp.com>
> > Cc: <cbm@rose.hp.com>; <csapuntz@cisco.com>; "dl-iscsi-eng"
> <dl-iscsi-eng@netapp.com>; <efri@sangate.com>;
> > <ips@ece.cmu.edu>; "Kalman Meth" <meth@il.ibm.com>; <ips@ece.cmu.edu>
> > Sent: Saturday, April 26, 2003 12:44 AM
> > Subject: Re: iSCSI: ISID RULE and Discovery sessions
> >
> >
> > > It is true that  in the discovery session the initiator does not have to
> > > specify a TargetName as  the purpose of the discovery session was to
> > > discover the targets.
> > > As such the discovery session is technically a session with the "iSCSI
> > > Node" and the only thing that can bring it down is logout or another
> > > discovery session with the same InitiatorName and Isid.
> > >
> > > Regards,
> > > Julo
> > >
> > >
> > >
> > > "Pittman, Joseph" <Joseph.Pittman@netapp.com>
> > > 25/04/03 21:08
> > >
> > > To
> > > Julian Satran/Haifa/IBM@IBMIL, Kalman Meth/Haifa/IBM@IBMIL,
> > > <csapuntz@cisco.com>, <efri@sangate.com>, <cbm@rose.hp.com>,
> > > <ips@ece.cmu.edu>
> > > cc
> > > "dl-iscsi-eng" <dl-iscsi-eng@netapp.com>
> > > Subject
> > > iSCSI: ISID RULE and Discovery sessions
> > >
> > >
> > >
> > >
> > >
> > >
> > > iSCSI specification authors and experts,
> > > My name is Joe Pittman, an engineering at Network Appliance.
> > > My group has implemented an iSCSI target based on draft 20
> > > of the iSCSI specification.
> > > During interoperability testing, we have encountered an initiator
> > > (Cisco Linux initiator from SourceForge), whose implementers have
> > > interpreted the ISID RULE differently from the NetApp target
> > > implementation.  I need an authoritative ruling on the applicability
> > > of the ISID RULE for Discovery sessions.
> > > The ISID RULE states the following (draft-ietf-ips-iscsi-20.txt,
> > > section 3.4.3):
> > >    ISID RULE: Between a given iSCSI Initiator and iSCSI Target Portal
> > >    Group (SCSI target port), there can only be one session with a given
> > >    value for ISID that identifies the SCSI initiator port.
> > > Consider the case where an initiator {InitiatorName X, ISID I} has
> > > created a Discovery session to a target.  Then, without terminating
> > > this session via LOGOUT, the same initiator {X,I} creates a new
> > > Normal session to the same target, at the same target portal.  The
> > > question is, should the target terminate the existing Discovery
> > > session in order to enforce the ISID RULE?
> > > Because there is no mention of Discovery sessions vs. Normal sessions
> > > in the ISID RULE section, my interpretation of the specification
> > > was that the existing Discovery session MUST be terminated.
> > >
> > > But one of the authors of the Cisco Linux initiator interpreted
> > > the specification differently.  Here is an excerpt from an e-mail
> > > message describing his logic:
> > > > Discovery sessions don't have TargetNames, and the implicit logout
> > > > only occurs when the InitiatorName, ISID, and TargetName all match.
> > > > It should thus be impossible for a normal session to logout a
> > > > discovery session, since the TargetNames for the two sessions can
> > > > never match.  I think your target has a bug.
> > > >
> > > > Discovery sessions don't really connect to a particular iSCSI
> > > > target.  It's more a connection to the iSCSI Node as a whole.
> > > > Normal sessions connect to particular iSCSI targets.  This should
> > > > keep the two session types from conflicting, even if the ISIDs
> > > > are the same.
> > >
> > > So, will one of you authors rule on this disagreement?  I am
> > > eager to fix my bug, if my interpretation was in error.
> > > One followup question:
> > > Also, if the Cisco interpretation is correct, then does the ISID
> > > rule apply to two Discovery sessions?  That is, if the target
> > > receives a second Discovery session while the first Discovery
> > > session is still active, MUST the target terminate the first
> > > Discovery session in order to enforce the ISID RULE?
> > >
> > > Thanks in advance for any help you can provide.
> > > --
> > > Joe Pittman
> > > jpittman@netapp.com
> > >
>
>


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