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    iSCSI: Representing iSCSI devices on FC fabrics



    			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
    


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Last updated: Fri Nov 16 02:17:47 2001
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