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 h3276X404213 for ips-outgoing; Wed, 2 Apr 2003 02:06:33 -0500 (EST) X-Authentication-Warning: ece.cmu.edu: majordom set sender to owner-ips@ece.cmu.edu using -f Received: from e31.co.us.ibm.com (e31.co.us.ibm.com [32.97.110.129]) by ece.cmu.edu (8.11.0/8.10.2) with ESMTP id h3276S304208; Wed, 2 Apr 2003 02:06:28 -0500 (EST) Received: from westrelay04.boulder.ibm.com (westrelay04.boulder.ibm.com [9.17.193.32]) by e31.co.us.ibm.com (8.12.9/8.12.2) with ESMTP id h3275TgJ067256; Wed, 2 Apr 2003 02:05:29 -0500 Received: from d03nm115.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.193.82]) by westrelay04.boulder.ibm.com (8.12.8/NCO/VER6.5) with ESMTP id h3276LVt221574; Wed, 2 Apr 2003 00:06:21 -0700 To: Eddy Quicksall Cc: ips@ece.cmu.edu, Kevin Gibbons , owner-ips@ece.cmu.edu MIME-Version: 1.0 Subject: RE: iSCSI: Portal Group clarification X-Mailer: Lotus Notes Release 5.0.11 July 24, 2002 From: John Hufferd Message-ID: Date: Tue, 1 Apr 2003 23:03:41 -0800 X-MIMETrack: Serialize by Router on D03NM115/03/M/IBM(Release 6.0 [IBM]|December 16, 2002) at 04/02/2003 00:03:41, Serialize complete at 04/02/2003 00:03:41 Content-Type: multipart/alternative; boundary="=_alternative 0027031C88256CFC_=" Sender: owner-ips@ece.cmu.edu Precedence: bulk This is a multipart message in MIME format. --=_alternative 0027031C88256CFC_= Content-Type: text/plain; charset="us-ascii" Eddy, Your point is exactly correct! The key point that was being missed was the words at the bottom of the figure on page 40 which says "(within Network Entity, not shown)". When one has more than one target (node) within a Network Entity, the portal (IP Address:Port) can be part of any of the enclosed Targets. That is because the path to the Target is defined by the portal (IP Address:Port) and the Target Name. This is reasonable since nothing is ambiguous about the description of the path that is intended. Having said that, there is also NO requirement that all portals need be connectable to all targets within the Network Entity. This is an implementation decision. (Just thought I would through that in.) Your point is also supported by the figure in section 3.4 and also the following example that describes what is returned by SendTargets for a Network Entity that has two iSCSI targets: - iSCSI Draft20 Appendix D : SendTargets Operation "The next example has two internal iSCSI targets, each accessible via two different ports with different IP addresses. The following is the text response: TargetName=iqn.1993-11.com.example:diskarray.sn.8675309 TargetAddress=10.1.0.45:3000,1 TargetAddress=10.1.1.45:3000,2 TargetName=iqn.1993-11.com.example:diskarray.sn.1234567 TargetAddress=10.1.0.45:3000,1 TargetAddress=10.1.1.45:3000,2 " . . John L. Hufferd Senior Technical Staff Member (STSM) IBM/System Group, 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 Eddy Quicksall Sent by: owner-ips@ece.cmu.edu 04/01/2003 05:13 PM To: Kevin Gibbons , ips@ece.cmu.edu cc: Subject: RE: iSCSI: Portal Group clarification Yes. Note however that a Network Portal can belong to more than one Target Portal Group but only one Target Portal Group within a single node (which is a target in this context). Eddy -----Original Message----- From: Kevin Gibbons [mailto:kgibbons@NishanSystems.com] Sent: Tuesday, April 01, 2003 6:39 PM To: ips@ece.cmu.edu Subject: iSCSI: Portal Group clarification Hi, I would like to make sure I understand the iSCSI model correctly. Can anyone confirm that a Portal, providing access to a target, is part of exactly one Portal Group at a time? My reading of the spec indicates this is true. That each Portal has a 16 bit Portal Group tag. But I would like to make sure. I believe that in iSCSI draft 20, it states that a Portal can be part of exactly one Portal Group. Please see page 15: - Portal Groups: iSCSI supports multiple connections within the same session; some implementations will have the ability to combine connections in a session across multiple Network Portals. A Portal Group defines a set of Network Portals within an iSCSI Network Entity that collectively supports the capability of coordinating a session with connections spanning these portals. Not all Network Portals within a Portal Group need participate in every session connected through that Portal Group. One or more Portal Groups may provide access to an iSCSI Node. Each Network Portal, as utilized by a given iSCSI Node, belongs to exactly one portal group within that node. Also, please see page 39 for similar wording. There is also a figure on page 40: ----------------------------IP Network--------------------- | | | +----|---------------|-----+ +----|---------+ | +---------+ +---------+ | | +---------+ | | | Network | | Network | | | | Network | | | | Portal | | Portal | | | | Portal | | | +--|------+ +---------+ | | +---------+ | | | | | | | | | | Portal | | | | Portal | | | Group 1 | | | | Group 2 | +--------------------------+ +--------------+ | | | +--------|---------------|--------------------|--------------------+ | | | | | | +----------------------------+ +-----------------------------+ | | | iSCSI Session (Target side)| | iSCSI Session (Target side) | | | | | | | | | | (TSIH = 56) | | (TSIH = 48) | | | +----------------------------+ +-----------------------------+ | | | | iSCSI Target Node | | (within Network Entity, not shown) | +------------------------------------------------------------------+ Please let me know if I am in error. Thanks very much! Kevin ------------------------------------------------- Kevin Gibbons Nishan Systems, Inc. kgibbons@NishanSystems.com (408) 519-3756 ------------------------------------------------- --=_alternative 0027031C88256CFC_= Content-Type: text/html; charset="us-ascii"
Eddy,
Your point is exactly correct!

The key point that was being missed was the words at the bottom of the figure on page 40 which says "(within Network Entity, not shown)".

When one has more than one target (node) within a Network Entity, the portal (IP Address:Port) can be part of any of the enclosed Targets.  That is because the path to the Target is defined by the portal (IP Address:Port) and the Target Name.  This is reasonable since nothing is ambiguous about the description of the path that is intended.  

Having said that, there is also NO requirement that all portals need be connectable to all targets within the Network Entity.  This is an implementation decision.  (Just thought I would through that in.)

Your point is also supported by the figure in section 3.4  and also the following example that describes what is returned by SendTargets for a Network Entity that has two iSCSI targets:

- iSCSI Draft20 Appendix D : SendTargets Operation
 "The next example has two internal iSCSI targets, each accessible via
  two different ports with different IP addresses.  The following is
  the text response:

        TargetName=iqn.1993-11.com.example:diskarray.sn.8675309
        TargetAddress=10.1.0.45:3000,1
        TargetAddress=10.1.1.45:3000,2
        TargetName=iqn.1993-11.com.example:diskarray.sn.1234567
        TargetAddress=10.1.0.45:3000,1
        TargetAddress=10.1.1.45:3000,2   "
       

.
.
John L. Hufferd
Senior Technical Staff Member (STSM)
IBM/System Group, 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


Eddy Quicksall <eddy_quicksall@ivivity.com>
Sent by: owner-ips@ece.cmu.edu

04/01/2003 05:13 PM

       
        To:        Kevin Gibbons <kgibbons@NishanSystems.com>, ips@ece.cmu.edu
        cc:        
        Subject:        RE: iSCSI: Portal Group clarification



Yes.

Note however that a Network Portal can belong to more than one Target Portal
Group but only one Target Portal Group within a single node (which is a
target in this context).

Eddy

-----Original Message-----
From: Kevin Gibbons [mailto:kgibbons@NishanSystems.com]
Sent: Tuesday, April 01, 2003 6:39 PM
To: ips@ece.cmu.edu
Subject: iSCSI: Portal Group clarification

Hi, I would like to make sure I understand the iSCSI model correctly.  Can
anyone confirm that a Portal, providing access to a target, is part of
exactly one Portal Group at a time?  My reading of the spec indicates this
is true.  That each Portal has a 16 bit Portal Group tag.  But I would like
to make sure.

I believe that in iSCSI draft 20, it states that a Portal can be part of
exactly one Portal Group.  Please see page 15:

  - Portal Groups: iSCSI supports multiple connections within the same
  session; some implementations will have the ability to combine
  connections in a session across multiple Network Portals. A Portal
  Group defines a set of Network Portals within an iSCSI Network
  Entity that collectively supports the capability of coordinating a
  session with connections spanning these portals. Not all Network
  Portals within a Portal Group need participate in every session
  connected through that Portal Group. One or more Portal Groups may
  provide access to an iSCSI Node. Each Network Portal, as utilized by
  a given iSCSI Node, belongs to exactly one portal group within that
  node.

                Also, please see page 39 for similar wording.  There is also a
figure on page 40:

    ----------------------------IP Network---------------------
           |               |                    |
      +----|---------------|-----+         +----|---------+
      | +---------+  +---------+ |         | +---------+  |
      | | Network |  | Network | |         | | Network |  |
      | | Portal  |  | Portal  | |         | | Portal  |  |
      | +--|------+  +---------+ |         | +---------+  |
      |    |               |     |         |    |         |
      |    |    Portal     |     |         |    | Portal  |
      |    |    Group 1    |     |         |    | Group 2 |
      +--------------------------+         +--------------+
           |               |                    |
  +--------|---------------|--------------------|--------------------+
  |        |               |                    |                    |
  |  +----------------------------+  +-----------------------------+ |
  |  | iSCSI Session (Target side)|  | iSCSI Session (Target side) | |
  |  |                            |  |                             | |
  |  |       (TSIH = 56)          |  |       (TSIH = 48)           | |
  |  +----------------------------+  +-----------------------------+ |
  |                                                                  |
  |                     iSCSI Target Node                            |
  |             (within Network Entity, not shown)                   |
  +------------------------------------------------------------------+


Please let me know if I am in error.
                Thanks very much! Kevin

-------------------------------------------------
Kevin Gibbons
Nishan Systems, Inc.
kgibbons@NishanSystems.com
(408) 519-3756
-------------------------------------------------

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