Subject: [Lime] LIME: One model versus two models

From: Benoit Claise <[email-masked]>
Date: Tue, 24 Nov 2015 14:00:41 +0100

Dear all,

Reflecting on the current state of affairs in LIME and a couple of 
discussions during the IETF 94 meeting ...

Let's start by quoting the charter:

    "This work will enable consistent configuration, reporting, and
    presentation for the OAM mechanisms used to manage the network,
    regardless of the layers and technologies, including management
    mechanisms to facilitate better mapping between information reported
    from OAM mechanisms that operate in different network layers."

The intent behind the charter was to shoot for a single model, i.e. a 
common structure for _all _OAM technologies to provide consistent 
configuration, reporting, and presentation, to be augmented with 
technology specific concepts.
However, we also have to recognize that there has been an experimental 
aspect to this charter: we could not assert that a single model would be 
suitable without going through the exercise. And the discussions (for 
some time) block on the significant differences between 
connection-orientated and connection-less data planes.

Let me stress that if a single model to rule them all is impossible, but 
two different generic models, one for connection-oriented and another 
one for connection-less OAM data plane, this is a conclusion already. 
And this should be fine with the charter text. Btw, note the "s" in YANG 
data models in this charter sentence: "- YANG data model(s) for generic 
layer-independent and technology-independent configuration, reporting 
and presentation for OAM mechanisms."

Now, I believe that the end points should be defined independently of 
the data plane technology. There is some commonalities after all, even 
if this is only in a YANG typedef. Another aspects to keep in mind is 
that we must be able to map those end points with the topology YANG 
models specified in I2RS: draft-ietf-i2rs-yang-l2-network-topology-01 
<http://datatracker.ietf.org/doc/draft-ietf-i2rs-yang-l2-network-topology/>, 
draft-ietf-i2rs-yang-l3-topology-00 
<http://datatracker.ietf.org/doc/draft-ietf-i2rs-yang-l3-topology/>, and 
draft-ietf-i2rs-yang-network-topo-01 
<http://datatracker.ietf.org/doc/draft-ietf-i2rs-yang-network-topo/>

Regards, Benoit (OPS AD)