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    RE: iSCSI: Portal Group clarification



    Siva,
    	The iSCSI Architecture model, draft 20, has one Portal Group Tag
    assigned per Portal, with the Portal to Portal Tag mapping unique for each
    Storage Node within an Entity.  Therefore, each Portal has one valid Portal
    Group Tag value per Storage Node in an Entity.
    	The iSNS model is an Entity object containment model, where each
    Storage Node has access to each Portal in an Entity.  With this model, the
    Portal to Portal Tag mapping is unique within an Entity.  Therefore, each
    Portal has one valid Portal Group Tag value in an Entity.
    	I have been working on an update to the iSNS model that allows a
    Portal Group Tag mapping to exist per iSCSI Storage Node.  I first wanted to
    make sure I understood the iSCSI Architecture model.  I have been reviewing
    examples/literature and comparing them to draft 20, as well as discussing
    options with the iSNS co-authors.
    	The intent is to make a small change to the iSNS model, keeping the
    existing iSNS attributes, yet support all possible iSCSI Portal Group Tag
    assignments.  I hope to have an update to the iSNS draft ready for WG review
    shortly.
    
    	Thanks, Kevin
    
    -----Original Message-----
    From: Siva Vaddepuri [mailto:Siva.Vaddepuri@MCDATA.com] 
    Sent: Friday, April 18, 2003 11:02 AM
    To: 'Eddy Quicksall'; Kevin Gibbons; ips@ece.cmu.edu
    Subject: RE: iSCSI: Portal Group clarification
    
    
    
    
    iSNS Draft data model is not consistent with iSCSI Draft data model. In
    iSCSI Data Model a Portal can belong to multiple Portal Groups (though only
    once in each iSCSI Node). iSNS Draft data model does not allow this. 
    
    Is there any plan to resolve this problem in iSNS Data model? If so when can
    we expect a new data model?
    
    iSNS draft data model defines Portal as (Section 4.1.1 page 23 in draft 18)
        
       PORTAL             IP Address                   *      *        * 
                          TCP/UDP Port                 *      *        * 
                          Portal Symbolic Name                * 
                          ESI Interval                        * 
                          ESI Port                            * 
                          Portal Group Tag                    * 
                          Portal Index                        * 
                          SCN Port                            * 
                          Portal Security Bitmap              * 
                          Portal IKE Phase-1 Proposal 
                          Portal IKE Phase-2 Proposal 
                          Portal Certificate 
    
    And it clearly says that the key is {IP Address, TCP/UDP Port} pair. This
    definition does not allow for registration of Portal which belongs to
    multiple Portal Groups (only once in a single iSCSI Node). 
    
    Thanks,
    Siva
    
    
    -----Original Message-----
    From: Eddy Quicksall [mailto:eddy_quicksall@ivivity.com]
    Sent: Friday, April 04, 2003 5:08 AM
    To: Kevin Gibbons; ips@ece.cmu.edu
    Subject: RE: iSCSI: Portal Group clarification
    
    
    Thanks,
     
    When I created the diagram, it was just to help me see what the
    configurations could be. I then started adding quotes from the spec. Then I
    added the titles as a "prompt". The titles are not to describe the objects.
    There are several 
     
    If you or someone else has some idea as to what title to put over the IP
    address, that would be good ... but the spec does not have a definition for
    that column.
     
    Eddy
     
    -----Original Message-----
    From: Kevin Gibbons [mailto:kgibbons@NishanSystems.com] 
    Sent: Thursday, April 03, 2003 9:49 PM
    To: 'Eddy Quicksall'; KRUEGER,MARJORIE (HP-Roseville,ex1); ips@ece.cmu.edu
    Subject: RE: iSCSI: Portal Group clarification
     
    Eddy,
        looks good to me, except the IP-Address boxes do not have a title above
    them, unlike the "Network Portals", and "Target Portal Groups" above the
    other boxes. Perhaps if "Network Portals" was removed above the TCP port
    numbers, or the title was moved to the left, or the IP-Address boxes were
    also titled, it would be clearer.
            Cheers, Kevin
    -----Original Message-----
    From: Eddy Quicksall [mailto:eddy_quicksall@ivivity.com] 
    Sent: Thursday, April 03, 2003 5:02 PM
    To: KRUEGER,MARJORIE (HP-Roseville,ex1); 'Kevin Gibbons'; ips@ece.cmu.edu
    Subject: RE: iSCSI: Portal Group clarification
    See what you think of this (if attachments get reflected). 
     
    You will notice that I don't draw lines around things like a "Network
    Portal" or a "Target Portal Group" because that does not depict what I'm
    trying to show ... that information is in the text. For example, "A Network
    Portal is identified by its IP address and its listening TCP port" and I
    show that by the connecting lines. The same comment applies to a Target
    Portal Group.
     
    Johns diagram shows these groupings quite nicely.
     
    Eddy
     
    -----Original Message-----
    From: Eddy Quicksall 
    Sent: Thursday, April 03, 2003 7:42 PM
    To: 'KRUEGER,MARJORIE (HP-Roseville,ex1)'; 'Kevin Gibbons'; ips@ece.cmu.edu
    Subject: RE: iSCSI: Portal Group clarification
     
    Kevin and Marjorie,
     
    Thanks for pointing that out. When I made the diagram, I didn't really
    intend to show an object diagram. I intended to show the flow and connecting
    lines between logical parts.
     
    I'll see if I can make a change that will properly depict the Network
    Entity.
     
    Eddy
     
    -----Original Message-----
    From: KRUEGER,MARJORIE (HP-Roseville,ex1) [mailto:marjorie.krueger@hp.com] 
    Sent: Thursday, April 03, 2003 6:31 PM
    To: 'Kevin Gibbons'; ips@ece.cmu.edu
    Subject: RE: iSCSI: Portal Group clarification
     
    The drawing in
    http://www.haifa.il.ibm.com/satran/ips/EddyQuicksall-iSCSI-in-diagrams/porta
    l_groups.pdf  has used the label "network entity" in a manner inconsistent
    with the usage/intent in the iSCSI protocol specification.  A "network
    entity" is meant to represent a computer system with ethernet egress points.
    As a computer system, it can contain one iSCSI Node if it's an initiator,
    and one or more iSCSI Nodes if it's a target.    It's not correct to talk
    about an iSCSI Node "accessing" a network entity, it's a containment
    relationship.
     
    Portal tags must only be unique within the scope of a single iSCSI target
    node, and are 16 bit integers.  I don't see where you get the UTF-8 out of
    the examples in (1)?  I just see numbers, with no mention of what format
    they must be exchanged in.  Of course, SendTargets commands are character
    strings, so the exchange of TargetPortalGroupTags are integers represented
    in character format.
     
    Marjorie Krueger
    Networked Storage Architecture
    Networked Storage Solutions
    Hewlett-Packard 
    -----Original Message-----
    From: Kevin Gibbons [mailto:kgibbons@NishanSystems.com] 
    Sent: Thursday, April 03, 2003 1:17 PM
    To: ips@ece.cmu.edu
    Cc: 'John Hufferd'; Eddy Quicksall
    Subject: RE: iSCSI: Portal Group clarification
    I have been reviewing the iSCSI Model examples on
    http://www.haifa.il.ibm.com/satran/ips , and am trying to get them straight
    in my head.  I was hoping someone can help. Network Entity: Can different
    entities provide access to the same iSCSI Node? In 1) "iSCSI Configuration
    Examples",
    http://www.haifa.il.ibm.com/satran/ips/iSCSIConfigurationExamples.pdf, the
    iSCSI Network Entity contains iSCSI Nodes and Network Portals. Each Network
    Portal has a TCP/IP network address. This limits access to an iSCSI Node to
    one Entity, and seems to agree with the architecture model in the iSCSI
    draft.  But 2) "Portal Groups",
    http://www.haifa.il.ibm.com/satran/ips/EddyQuicksall-iSCSI-in-diagrams/porta
    l_groups.pdf, shows Network Entities that provide access to, but do not
    contain, Network Portals and iSCSI Nodes.  These feed into Portal Groups and
    then iSCSI Nodes.  This would mean multiple Entities can provide access to
    the same iSCSI Node, and the example (2) shows this. This seems to disagree
    with (1). I tried but could not map this into the iSCSI draft architecture
    model. Portal Tags: Are they uniquely defined using 16 bit integers?  In 1)
    "iSCSI Configuration Examples" figures, the Portal Tags are specified using
    UTF-8 characters.  But the included Send Targets examples use integer
    values.  In
    2) "Portal Groups", integer values are used for defining Portal Tags. This
    seems to agree with the iSCSI draft. Is there a UML/entity-relationship
    model for the iSCSI architecture?  This would help me a lot.  I am aware of
    one for the iSCSI MIB model, but not the iSCSI Architecture. 
        Many Regards, Kevin
    -----Original Message-----
    From: John Hufferd [mailto:hufferd@us.ibm.com] 
    Sent: Tuesday, April 01, 2003 11:04 PM
    To: Eddy Quicksall
    Cc: ips@ece.cmu.edu; Kevin Gibbons; owner-ips@ece.cmu.edu
    Subject: RE: iSCSI: Portal Group clarification
    
    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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