RE: iSCSI: Representing iSCSI devices on FC fabrics

["Jim Hafner" <hafner@almaden.ibm.com>]

Rob,

You make a good point.  But I think it should also be mentioned that going
the route indicated in the first reply may NOT guarantee WWUniqueness (what
if two vendors do the same thing!).

Jim Hafner


"Elliott, Robert" <Robert.Elliott@compaq.com>@ece.cmu.edu on 11/16/2001
07:33:27 am

Sent by:  owner-ips@ece.cmu.edu


To:   <ips@ece.cmu.edu>
cc:
Subject:  RE: iSCSI: Representing iSCSI devices on FC fabrics



Beware than a FC WWN is not the same as an EUI-64.  They're both based
on the IEEE OUI/company_id, but the FC WWN uses the 4 most significant
bits for a "Name Address Authority" field and has 4 fewer bits available
in the vendor specified portion.

EUI-64 = (MSB) { 20-bit company_id,
                 44-bit vendor specified } (LSB)

FC WWN = (MSB) { 4-bit NAA field,
                 20-bit company_id,
                 40-bit vendor specified } (LSB)
         (for the IEEE Registered NAA type)

---
Rob Elliott, Compaq Server Storage
Robert.Elliott@compaq.com



> -----Original Message-----
> From: Thanu Skariah [mailto:tskariah@npd.hcltech.com]
> Sent: Friday, November 16, 2001 1:12 AM
> 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