Subject: [lmap] Question on draft-schoenw-lmap-netconf-00.txt

From: "MORTON JR., ALFRED (AL)" <[email-masked]>
Date: Thu, 28 Feb 2013 19:06:47 -0500

Hi Juergen,

A question on your draft, which otherwise presents a clear examination
of NETCONF applicability to the LMAP MA-Controller-Collector communications.

4.4.  Pushing of Measurement Results

   NETCONF has not been designed as a data push protocol.  While a
   NETCONF extension [RFC5277] provides support for event notifications,
   this mechanism requires in its simplest form that a NETCONF client
   first subscribes to an event stream and that the session used to
   carry event notification stays open.  This is not scalable in the
   LMAP scenario.
   ...< short description of an alternative snipped > ...

   That said, if close to soft real-time pushing of measurement results
   form the MA to the collector is required, then NETCONF likely is not
   the right choice.

This last sentence left me wondering.  What about the demands of 
near-real-time reporting would be difficult for NETCONF ?

We might still look at NETCONF's ability
relative to other existing protocols, unless you believe it should be ruled-out.
This near-real-time-push capability would be important for some use cases,
such as the subscriber call to the SP hotline mentioned earlier today. 

regards,
Al

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From: Juergen Schoenwaelder <[email-masked]>
Date: Fri, 1 Mar 2013 08:39:43 +0100

> such as the subscriber call to the SP hotline mentioned earlier today. 

I think there are two options:

1) Test results are recorded in the data model maintained by the
   NETCONF server and a NETCONF client pulls the results.

2) Test results are pushed asynchronously as notifications towards the
   NETCONF client.

If there is a decent call-home solution, then both can likely be made
to work, perhaps even combinations like notification triffered pulls.

For the use case you have in mind, a single protocol like NETCONF
would likely even provide benefits - you could define a new NETCONF
operation that runs a test and returns the results. Again, the
challenge is the call home mechanism - if the MA is behind a NAT, how
do you establish a connection to it when the subscriber calls?

I think the sentence that left you wondering should probably not given
too much weight. The question really is whether under normal operation
soft real-time pushing is needed or even desirable. It seems certain
MAs tend to collect results locally and then send results in batches,
which makes a lot of sence. This kind of batch delivery seems feasible
with NETCONF. Constant streaming is likely undesirable regardless
choice of the protocol since keeping a large number of transports open
(including security state) all the time seems not scalable.

/js

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: +49 421 200 3587         Campus Ring 1, 28759 Bremen, Germany
Fax:   +49 421 200 3103         <http://www.jacobs-university.de/>