Re: [L2sm] Adoption poll for draft-wen-l2sm-l2vpn-service-model-03.txt

Scott Mansfield <> Tue, 03 January 2017 19:19 UTC

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From: Scott Mansfield <>
To: Benoit Claise <>, "" <>, "" <>
Thread-Topic: [L2sm] Adoption poll for draft-wen-l2sm-l2vpn-service-model-03.txt
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Date: Tue, 3 Jan 2017 19:19:18 +0000
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Subject: Re: [L2sm] Adoption poll for draft-wen-l2sm-l2vpn-service-model-03.txt
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I agree with Benoit.  There are many dimensions to the modeling space and we can't let the perfect be the enemy of the good.  Constant communication and sharing will help alignment while allowing the people that actually run networks to get what they need.  30+ years of object-oriented software development (should have) taught all designers/architects/programmers that the first iteration of a solution is not the best and most optimized.  Each iteration provides the opportunity to abstract, refine, refactor, and extend.  Proper information hiding and encapsulation is key.  Automation is very important and we need to work together to ensure that whatever models that are created are supported by tools that allow for effective reuse and extensions.


From: Benoit Claise []
Sent: Thursday, December 22, 2016 8:44 AM
To:;; Scott Mansfield <>
Subject: Re: [L2sm] Adoption poll for draft-wen-l2sm-l2vpn-service-model-03.txt

Dear all,

A couple of reflections on L2SM, just before the end of year break.

First, I want to quote one chairs slides<>
We really need this to be driven by Operators
    - Of course, vendors can and should participate
    - But be aware of how the data model is use
I'm always baffled when vendors 'seem to) know better than the operators what they need. I don't believe we have spent enough time listening to the few operators in the room during the WG meeting.
We have here a group of operators who want to do work in the IETF, and we should respect that.

Second, on the differences between IETF and MEF service management.
MEF wants to go for the full LSO architecture (billing, SLA, order management, etc.). Perfect.
L2SM charter wants to do something similar to L3SM: a self-contained service YANG module.
It would be nice to try to fit the L2SM service models in the MEF LSO architecture, but the L2SM work follows a different architectural model to LSO, and that there is no value in trying to match the functions across model at all costs. This should not invalidate either approach, only observe that they are different.

Third, exactly like the L3SM draft, the L2SM draft includes a number of technology-specific parameters and these have caused people to claim that the I-D must be describing a normalised or configuration model. But (of course?) the parameters are needed to configure the CE-PE access connections. This is a suitable point of differentiation between MEF and L2SM that MEF has worked on CE-based models while L2SM will work on PE-based models. Indeed, the IETF works on the networking aspects. However, when a building is done somewhere else (typical example, SLA management done in MEF), this L2SM YANG module should only contain a place holder or a pointer.

Fourth. Discussing those very topics live with Scott Mansfield (our MEF - IETF liaison manager) during a workshop recently, we agree that both IETF and MEF service models have a place. While we start to see some consolidation in terms of YANG modules for device management, we are only at the beginning of YANG service modules.

I hope this is useful and that it clarifies the situation.

Regards, Benoit


Our charter mandates that we consider basing our work on


As we discussed in the meeting, that draft is not perfect. But when I asked the

room whether we thought that it would provide a good starting point that we

could work with to polish and adapt to become the I-D that we ultimately submit

for publication as an RFC, I believe I heard a good hum in favour and silence in


So this email starts a formal poll for adoption. Please answer:

Do you think that the WG should adopt draft-wen-l2sm-l2vpn-service-model-03.txt?

If "yes," it would help if you could indicate whether you have read the draft

and how happy you are with it.

If "no", it is important that you provide reasons.

This poll will last for two weeks, ending on Saturday 3rd December.

Just to reassure everyone that adoption does not imply that anything is set in

stone: we expect the WG to continue to develop the content and change whatever

needs to be changed.


Adrian and Qin


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