iSCSI Boot: use of iSNS

[Kevin Gibbons <kgibbons@NishanSystems.com>]

At the IPS WG session at IETF 56, we discussed the iSCSI Boot draft.  It
involved how to find the iSCSI target to boot from, as well as security
issues for the process.  The following is a process using DHCP and iSNS to
find the appropriate iSCSI target to use for boot:
1) use DHCP to find the iSNS Server.  Please see:
	http://www.ietf.org/internet-drafts/draft-ietf-dhc-isnsoption-05.txt

2) query the iSNS server to find the Discovery Domain Feature "Boot List
Enabled" for the specified iSCSI node or entity.  Please see:
	http://www.ietf.org/internet-drafts/draft-ietf-ips-isns-18.txt
---
6.10.2.9 Discovery Domain Features 
   The Discovery Domain Features is a bitmap indicating the features of 
   this DD.  The bit positions are defined below.  A bit set to 1 
   indicates the DD has the corresponding characteristics. 

       Bit Position     DD Feature 
       ------------     ---------- 
          31 (Lsb)      Boot List Enabled (1)/Boot List Disabled (0) 
        All Others      RESERVED 
    
   Boot List: this feature indicates that the targets in this DD provide 
   boot capabilities for the member initiators, as described in [iSCSI-
   boot].
---
Couple items:
1) The iSNS Server provides the ability to distribute security policies.
2) The size of an iSNS Client may vary.  However, the code to query the iSNS
server for a boot-list enabled DD based on an iSCSI name is not very
complex.  Most of the complexity in iSNSP is on the server side.
3) SLPv2 and multicast are other alternative methods to DHCP to find the
iSNS server.  Additionally, SLPv2 is an alternative to iSNS for locating the
target to boot from, which is already described in iSCSI-boot.

	Cheers! Kevin

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Kevin Gibbons
Nishan Systems, Inc.
kgibbons@NishanSystems.com
(408) 519-3756
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