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    RE: iSCSI: Aggregation tags in SendTargets



    Yes, I think the first rule should be re-worded to say
    something like the following:
    
       A tag MUST NOT be used with addresses that do not support
       sessions spanning multiple connections.
    
    I also think a new rule should be added to clarify the case
    John is talking about.  Perhaps the following:
    
       A target that supports a session spanning multiple connections,
       but only to the same address MUST use a unique tag.
    
    Paul
     
    +--------------------------+----------------------------+
    + Paul Congdon             + Email: paul_congdon@hp.com +
    + Hewlett Packard Company  + Mail Stop:  5662           +
    + HP ProCurve Networking   + Phone:  (916) 785-5753     +
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    > 
    > Mark,
    > You might want to modify your first rule, it does not take 
    > into count the
    > condition where a single address can have more then one 
    > connection to the
    > same session, but only to the same IP address.
    > 
    > .
    > .
    > .
    > John L. Hufferd
    > Senior Technical Staff Member (STSM)
    > IBM/SSG San Jose Ca
    > (408) 256-0403, Tie: 276-0403,  eFax: (408) 904-4688
    > Internet address: hufferd@us.ibm.com
    > 
    > 
    > Mark Bakke <mbakke@cisco.com>@ece.cmu.edu on 05/15/2001 01:06:24 PM
    > 
    > Sent by:  owner-ips@ece.cmu.edu
    > 
    > 
    > To:   IPS <ips@ece.cmu.edu>
    > cc:
    > Subject:  iSCSI: Aggregation tags in SendTargets
    > 
    > 
    > 
    > 
    > During the interim meeting, we had discussed a proposal to
    > add an aggregation tag to the SendTargets response, indicating
    > which (if any) target addresses supported multiple connections
    > per session, and which groups of addresses an initiator could
    > hope to aggregate a session across.
    > 
    > Aggregation tags were generally well-received; a small modification
    > to the proposed method also allows an initiator to know whether
    > a single address supports multiple connections per session just
    > by itself.
    > 
    > Here is the section that would go into the NDT document.
    > 
    > --
    > 
    > (This would be added to section 4.2, right before the vendor-specific
    > paragraph at the end):
    > 
    > 
    >   If an iSCSI target supports multiple connections per session,
    >   it must indicate this by including an aggregation tag after each
    >   address, in the form of
    > 
    >     TargetAddress=address,tag
    > 
    >   Where "tag" is an ASCII, alpha-numeric string indicating an address
    >   group.  Within a single session, a connection may be 
    > requested to any
    >   combination of TCP addresses that have the same tag.  If an address
    >   supports multiple connections per session, but does not support
    >   spanning a session across other addresses, it will have its own
    >   tag.
    > 
    >   Here is an example:
    > 
    >     TargetName=fqn.com.acme.diskarray.sn.8675309
    >     TargetAddress=10.1.0.45:3000,1
    >     TargetAddress=10.1.1.46:3000,1
    >     TargetAddress=10.1.0.47:3000,2
    >     TargetAddress=10.1.1.48:3000,2
    >     TargetAddress=10.1.1.49:3000
    >     TargetAddress=10.1.1.50:3000,3
    >     TargetAlias=Oracle tables
    > 
    >   In this example, any of the target addresses can be used to reach
    >   the same target.  A single-connection session can be established
    >   to any of these TCP addresses.  A multiple-connection 
    > session could span
    >   addresses .45 and .46, or .47 and .48, but cannot span any other
    >   combination.  A TargetAddress without a tag (.49) cannot be combined
    >   with any other address within the same session.  A TargetAddress
    >   with a tag that is not shared with other addresses supports multiple
    >   connections per session, but all connections must be to the same
    >   address.
    > 
    >   To make this work, there are a few rules to follow:
    > 
    >   A target that does not support spanning sessions across multiple
    > addresses
    >   MUST NOT include the tags.
    > 
    >   A target that is accessible via multiple TCP addresses 
    > SHOULD include
    >   all TCP addresses in a SendTargets response.
    > 
    >   A target with multiple TCP addresses that supports a 
    > session spanning
    >   multiple TCP addresses MUST indicate TCP address groups 
    > using aggregation
    >   tages in a SendTargets response.
    > 
    >   Aggregation tags have no meaning or persistence beyond a particular
    >   SendTargets response.
    > 
    > 
    > 
    > --
    > Mark A. Bakke
    > Cisco Systems
    > mbakke@cisco.com
    > 763.398.1054
    > 
    > 
    > 
    


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Last updated: Tue Sep 04 01:04:42 2001
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