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Title: Message
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/portal_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
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
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| 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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Last updated: Thu Apr 03 17:19:15 2003
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