P1394 Mail Archive: Re: P1394> units and logical units definition

P1394 Mail Archive: Re: P1394> units and logical units definition

Re: P1394> units and logical units definition

Greg Shue (gregs@sdd.hp.com)
Mon, 16 Mar 1998 11:41:47 -0800 (PST)

>
> Greg Shue writes:
> > The SBP-2 proposal allows this to be modeled as:
> > 1 unit with:
> > 2 logins to the Print Job logical unit
> > N logins to the Printer Status logical unit
> > 1 login to the Printer control logical unit
> >
> > Similarly, since each of these services operate independently
> > of each other (and may be used by other protocol stacks), SBP-2
> > allows for them to be modeled as:
> > 2 + N + 3 units with 1 logical unit each
> > or:
> > 1 Print Job Unit Directory with 2 logical units (instances)
> > 1 Device Status Unit Directory with N logical units (instances)
> > 1 Device Control Unit Directory with 1 exclusive logical unit
> >
> > The current PWG proposal restricts the options to the last one.
>
> Even if each of those models is allowed by SBP-2, I think
> the first one (a single unit with multiple LUNs) is both more
> in the spirit of SBP-2 and more in the spirit of 1394. This
> model allows a 1394 node to have any number of independent
> printer units, which is good if you are a multi-function node
> like a computer or a fancy printer.
>
> The other model is difficult if you want to have multiple
> independent units in a node, because there is no clear way
> to match up which Device Status Unit Directory goes with which
> Device Control Unit Directory, or Print Job Unit Directory.
> Rev 0.1d of the profile doesn't show how to do this (or I
> missed it...)

No, you didn't miss it. It is not there. This may be an issue.

> So at face value I would prefer the first model (above) over
> the second.

The big problem with the first model is that you cannot have
multiple connections between device status applications and
device status services when the applications reside on the same
node. This _requires_ that multiplexing be done somewhere in the
system.

Smaller problems include how to figure out which LUNs are
associated with which type of service.

(Note: I was really figuring that device control would just be
a password-protected access into device status.)

Suggestions?

> --------------------------------------
> Eric Anderson ewa@apple.com
> Apple Computer, Inc. 408-974-8187
> --------------------------------------

-- 
Greg Shue
Hewlett-Packard Company
Office Products Division			gregs@sdd.hp.com
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