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Re: notification motivation and requirements



Randy Presuhn wrote:
Hi -

From: "Andy Bierman" <ietf@andybierman.com>
To: "David T. Perkins" <dperkins@dsperkins.com>
Cc: "Juergen Schoenwaelder" <j.schoenwaelder@iu-bremen.de>; <netconf@ops.ietf.org>
Sent: Wednesday, March 29, 2006 4:59 PM
Subject: Re: notification motivation and requirements

David T. Perkins wrote:
HI,

The wording is bad in my description below since it implies that
present day devices can determine when resulting conditions or
events are unexpected consequences of a config change.

So, please change it to the following:
 *) notifications that report changes in device state, or
    transient events so that the mmgmt app can determine
    any unexpected consequences of a configuration change.
Isn't this just a special-case of the general
requirement to provide enough info in each <notification>
so that it can be analyzed by an application independently
of the notification transport mechanism?  (Maybe that is a
new requirement.)

Maybe this is what Randy means by not binding to notification
delivery parameters to the session.
...

No, David is talking about something else.  He described a
scenario in which some way of associating a notification with
a particular configuration request would be valuable - if we employ
heuristics that might reasonably detected "unintended consequences"
of configuration requests.

Where this does fit together with what I was saying is whether we
consider it necessary for such a notification to be delivered on the
same connection as the configuration request that caused the potential
problems.  If we do, it's effectively an "oh, by the way, I noticed side-effects
X, Y, and Z" after the response to a configuration request.  If we separate
the subscription from the connection, it become "operation foo on
netconf connection bar seems to have precipitated side-effects X, Y, and Z".

Of course, this presumes that we have a way in protocol to talk about a
particular netconf connection.

Why do you need the agent to do anything fancy at all?
You lock the configuration.
You make changes with edit-config.  You wait a few seconds.
You look at any notifications that get generated.
If it's related to configuration, it's yours.

If it's not, then neither netconf or anything else can
be sure -- and what good does guessing do?  E.g.,
if I change the bridging configuration, and some notification
related to spanning tree comes up, it could just be a
coincidence, and the problem may be caused by another device.




Randy

Andy

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