RE: iSCSI: Representing iSCSI devices on FC fabrics

["KRUEGER,MARJORIE (HP-Roseville,ex1)" <marjorie_krueger@hp.com>]

This use of the eui. naming format will ONLY be acceptable if the iSCSI
gateway device is the only iSCSI gateway device in the world that is allowed
to "represent" these FC devices - can your implementation guarantee that?
Another iSCSI gateway on the same FC fabric (another of your gateways?)
might also use that naming convention (as Jim H points out) and that would
violate the requirements of iSCSI naming.

The eui. naming format was intended for use when the iSCSI device "owns" the
EUI number (as those FC devices "own" their WWN).  This gateway usage is not
what was intended.

Marjorie Krueger
Networked Storage Architecture
Networked Storage Solutions Org.
Hewlett-Packard
tel: +1 916 785 2656
fax: +1 916 785 0391
email: marjorie_krueger@hp.com 

> -----Original Message-----
> From: Thanu Skariah [mailto:tskariah@npd.hcltech.com]
> Sent: Thursday, November 15, 2001 11:12 PM
> To: Robert Grant
> Cc: 'ips@ece.cmu.edu'
> Subject: Re: iSCSI: Representing iSCSI devices on FC fabrics
> 
> 
> Robert,
> 
> 
>     iSCSI allows different naming formats, of which one 
> format is the EUI
> format  (See the example
> in sec 2.2 .7 and the naming draft -
> http://www.ietf.org/internet-drafts/draft-ietf-ips-iscsi-name-
> disc-02.txt )
> 
>     The EUI representation  is of the form eui . <WWN>.  Each 
> FC device's
> WWName
> can be used to form the corresponding iSCSI name for the 
> device.  This is what
> we are
> doing on a linux based software FCP/iSCSI gateway that we are 
> implementing, and
> this
> is why :
> 
> (From the naming and discovery draft ):
> 
> BeginQuote "
> 
> Type "eui." (IEEE EUI format)
> 
>    The IEEE iSCSI name might be used when a manufacturer is already
>    basing unique identifiers on World-Wide Names as defined 
> in the SCSI
>    SPC-2 specification.
> 
>    It may also be used by a gateway representing a Fibre Channel or
>    SCSI device that is already adequately identified using a 
> world-wide
>    name.
> 
> " End Quote
> 
> 
> Thanks,
> Thanu
> 
> 
> 
> Robert Grant wrote:
> 
> >                         Hello all,
> >
> >                         I have a question on the 
> representation of iSCSI
> > devices into Fibre Channel fabrics for an iSCSI-to-FC 
> "gateway" device and
> > would like to solicit people's thoughts on how best to do 
> this. A gateway
> > device will allow iSCSI devices and FCP devices to access 
> each other, but in
> > order to do this a consistent representation of the devices 
> is needed. I
> > haven't been able to reconcile the iSCSI and FCP standards 
> using what's
> > currently in the iSCSI standard, and wanted to see if there 
> was any support
> > to expanding the iSCSI standard to address this (a standard 
> solution is, of
> > course, much more preferred to every gateway vendor doing 
> it in their own
> > proprietary way). In particular, how would an iSCSI device 
> map onto Fibre
> > Channel's World Wide Name (WWN)? Would every device have 
> its own WWN, or
> > could many iSCSI devices use a single WWN? There have been 
> some discussions
> > (for example, there was even discussion of including a WWN 
> field in the
> > iSCSI Login for a Gateway to proxy with in
> > 
http://www.pdl.cmu.edu/mailinglists/ips/mail/msg01616.html), but what is the
> current view?
>
>                         A first approach might be that many iSCSI devices
> could use a single WWN. This can work well for FC-AL devices "directly
> attached " to the IP network or for small FC fabrics - and where the
> predominant interconnect and management of that interconnect is the IP
> network.
>
>                         This approach views the FC fabric as flat (or at
> least perhaps that FC zoning is "turned off"). As the FC fabric gets
bigger,
> though, this first approach can create two layers of management - one must
> first configure the FC network and then configure the IP network (since
the
> individual iSCSI devices sharing a single WWN can only be zoned as a
group).
> The two layers are first "this group of iSCSI devices can access this
zone"
> on the FC side and then "this iSCSI device can access this FC device in
this
> zone" on the iSCSI side. If there was a clean integration with FC zoning
> (and associated management of the FC zoning), this may be avoided.
>
>                         A further complication is that, as the FC fabric
> gets even bigger, a single iSCSI device could end up with multiple entry
> points (i.e. paths through multiple gateways) into a single FC fabric. Is
> there any common way to represent iSCSI devices (for instance, with
respect
> to WWNs) that allows the unique identification of that iSCSI device - even
> though there are multiple entrypoints onto the FC fabric? The case of
> multiple gateways (possibly from different vendors) is the clearest
example
> of the need for a standard.
>
>                         Thank you for your time and I look forward to all
> comments/suggestions.
>
> Regards,
> Rob
>
> Rob Grant
> McDATA Corporation