Juergen Schoenwaelder <j.schoenwael...@jacobs-university.de> wrote:
> On Fri, Dec 16, 2016 at 10:31:31AM +0100, Martin Bjorklund wrote:
> > Juergen Schoenwaelder <j.schoenwael...@jacobs-university.de> wrote:
> > > On Thu, Dec 15, 2016 at 05:26:09PM +0100, Martin Bjorklund wrote:
> > > > Juergen Schoenwaelder <j.schoenwael...@jacobs-university.de> wrote:
> > > > > On Thu, Dec 15, 2016 at 04:15:00PM +0100, Martin Bjorklund wrote:
> > > > > > Hi,
> > > > > > 
> > > > > > Issue https://github.com/netmod-wg/entity/issues/13
> > > > > > 
> > > > > >   Should the model support pre-configuration of hardware components?
> > > > > >   The current model supports pre-configuration of components 
> > > > > > provided
> > > > > >   the operator knows the name of the component to be installed. A 
> > > > > > more
> > > > > >   useful model would use the parent component, class, and
> > > > > >   parent-rel-pos as identification. If the system detects a 
> > > > > > component
> > > > > >   and there is configuration available for the parent component,
> > > > > >   class, and parent-rel-pos then the system would instatiate the
> > > > > >   component with the provided name, and optionally additional
> > > > > >   parameters.
> > > > > > 
> > > > > > See also various mails from Timothy Carey and Bart Bogaert on this
> > > > > > issue.
> > > > > > 
> > > > > > Personally, I think that we should add these nodes, since the ML
> > > > > > comments indicated that pre configuration is pretty useful.
> > > > > >
> > > > > 
> > > > > I am still not sure what exactly this will do. I have been looking at
> > > > > <https://www.ietf.org/mail-archive/web/netmod/current/msg17039.html>.
> > > > > I am provisioning mfg-name (Preferred value is the manufacturer name
> > > > > string actually printed on the component itself (if present).) but all
> > > > > I have is that something of a certain expected class has been plugged
> > > > > into a certain position of the parent container. Also note that
> > > > > mfg-name scopes comparisons of other properties. I would have similar
> > > > > questions concerning the model-name; how can a provisioning system
> > > > > predict the 'vendor-specific model name identifier'? Or is the whole
> > > > > idea that if I plug something that does not match, the component is
> > > > > left in a special state (which one)? If this is the intention, then
> > > > > this needs to be spelled out clearly somewhere.
> > > > 
> > > > The current model works fine if the user looks into the state list and
> > > > finds a component that he wants to configure.  To do this, he uses the
> > > > name of the component as found in the state list, and writes the
> > > > config for this component.
> > > > 
> > > > The current model also supports pre-configuration if the user somehow
> > > > can predict the name of a component to-be-inserted.  In this case he
> > > > can write the config, and when the component is plugged in, the system
> > > > will derive the component name, and check the config list for this
> > > > name.  This is a fragile model.
> > > > 
> > > > In the proposed model, the user can provide configuration for a tuple
> > > > (parent, class, parent-rel-pos).   If the server finds a component in
> > > > the state list (or such a component is later plugged in), then the
> > > > corresponding config leafs are used for the state of this component
> > > > (including the name).
> > > > 
> > > > If you plug in something that doesn't match the config list, well that
> > > > just means that nothing has been configured for this component, and
> > > > the system will populate the state list accordingly.
> > > >
> > > 
> > > Well, this is not what I read out of
> > > 
> > > https://www.ietf.org/mail-archive/web/netmod/current/msg17039.html
> > > 
> > > since there are leafs like mfg-name and model-name that seem to be
> > > hardware component properties.
> > 
> > The description statements in this email are just copied from the
> > corresponding config false nodes.  I think they need to be rewritten;
> > compare with serial-num.  This text can probably be further improved.
> > The idea is that the user probably would configure say mfg-name only
> > if the system cannot detect it automatically.
> 
> I still wonder why it could be useful to provision things like the
> mfg-name or the serial-num. I would rather like to know what is really
> there instead of overwriting these properties.

Note that entPhysicalSerialNum is read-write in the MIB.  I assume
that the reason for this is that operators can use this as an
inventory list, and manually enter the values that the system cannot
detect automatically.

> > > And the config list is still indexed by
> > > a name; so for list elements that have a (class, parent, position)
> > > triple, the name would be arbitrary and not necessarily matching the
> > > component name.
> > 
> > I think that the idea is that if there is a matching triple, then the
> > system MUST use the configured 'name' as the 'name' also in the state
> > list.  One reason for pre-confiugring these components is to be able
> > to refer to them in other config.
> 
> This may make sense.
> 
> > > Well, if you understand the edits,...
> > 
> > I think the idea would be explained along these lines:
> > 
> > The sytem conceptually behaves like this:
> > 
> > 1.  When a physical component is detected, the system will initialize
> >     an entry in the /hardware-state/component list.
> > 
> >     If there is an entry in /hardare/component list with a matching
> >     (class,parent,parent-rel-pos) triple, then the state entry is
> >     initialized with the configured values for all configured leafs
> >     (name, mfg-name, ...).
> > 
> >     If there is no such matching entry, the system assigns a 'name'
> >     in an implementation-specific manner.
> > 
> >     If there is an entry in /hardare/component list with a matching
> >     'name' and where the triple (class,parent,parent-rel-pos) is not
> >     set, then the state entry is initialized with the configured
> >     values for all configured leafs (name, mfg-name, ...).
> > 
> >     Otherwise, the state entry is initialized with the detected values
> >     for all leafs.
> > 
> > 2.  If the /hardware/component list is modified (i.e., someone changed
> >     the config), then the system MUST behave as if it was restarted
> >     and followed the procedure in (1).
> 
> This way of pre-configuring that name may indeed make sense. Lets see
> if this is what BBF really wanted.


/martin

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