Subject: iSCSI: Rationale behind the iSCSI WWUI URN Draft

From: Mark Bakke <[email-masked]>
Date: Fri, 16 Mar 2001 11:35:34 -0600

David has asked for a rationale behind this draft as
well.

Basically, the naming & discovery team set out to solve the
question "what's in a name?".  We produced a set of requirements
for naming initiators and targets, which resulted in the world-
wide unique identifier (WWUI).  During our research on what
constitutes good naming requirements, we looked that the requirements
that had been previously done in RFC 1737, "Functional Requirements
for Uniform Resource Names".  These requirements were very similar
to ours, and were well-specified.

We have been careful to keep separate the concept of a name and
an address.  A name is an identifier that is location-independent;
I can move a target to another address, or have multiple addresses
for it, but it is still the same target.  An address is also an
identifier, but it identifies a particular place, or access point,
at which the target may currently be found.

When configuring an initiator to talk to a target, either type of
identifier could be used.  An administrator that has the name (WWUI)
of the target can configure the name, and the initiator can use
one or more of the discovery procedures outlined in the naming and
discovery draft to resolve this name into one or more addresses.
An administrator that has the address of the target can configure
this address, and the discovery step can be skipped, unless the
address has changed.

The WWW and internet folks have already defined a similar set of structures.
A Uniform Resource Identifier (URI; RFC 1630, 2396) is used to identify something;
this identifier can be either a Uniform Resource Name (URN; RFC 2141),
or the more familiar Uniform Resource Locator (URL; RFC 1738).  These
address formats are familiar to users and administrators, are well-defined,
and include standard methods for handling non-ASCII characters, comparisons,
etc.

Since iSCSI implementations require the use and configuration of both
names and addresses, it makes sense to allow a user to specify these in
terms of normal, everyday strings, using URNs for names, and URLs for
addresses.

This draft (draft-bakke-issi-wwui-urn-00) is very simple; all it really does
is register the string "iscsi" as the top of iSCSI's URN name space, to
avoid other protocols or vendors using it and causing confusion.

For more information on URIs, URLs, and URNs, please see:

    http://www.w3.org/Addressing/

Hope this helps,

-- 
Mark A. Bakke
Cisco Systems
[email-masked]
763.398.1054