Subject: [netmod] diffserv model questions

From: Juergen Schoenwaelder <[email-masked]>
Date: Mon, 18 May 2015 19:20:36 +0200

Hi,

what is the purpose of the feature policy-template-support in
draft-asechoud-netmod-diffserv-model-01.txt? Can I use the model
without this feature?

I also note that no implementable object is left in
ietf-diffserv-policy if I do not support the feature
policy-template-support. Is this useful?

Is it a bug or a feature to support inline classifier definitions? Is
it correct that actions are always 'inline' so to say? Is this a bug
or a feature?

/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/>

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From: "Aseem Choudhary (asechoud)" <[email-masked]>
Date: Tue, 19 May 2015 19:57:26 +0000

Hi Juergen,

Please find the replies inline.

-thanks,
Aseem

>policy-template-support. Is this useful?

[AC] ietf-diffserv-policy module defines policy as a template. The other
option is to configure & apply it directly under target as defined in
ietf-diffserv-target module.
>it correct that actions are always 'inline' so to say? Is this a bug

[AC] Classifier can be defined inline or can be defined as a separate
template and referred in the policy definition.
     All the actions are defined inline. This is the most common use-case.
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From: Juergen Schoenwaelder <[email-masked]>
Date: Tue, 19 May 2015 22:39:29 +0200

> ietf-diffserv-target module.

OK, but why is there a feature since this 'policy' is an extension
defined in a separate YANG model?

> template and referred in the policy definition.

Yes, but is this a bug or a feature? From an implementation
perspective, this sounds like extra cost. So what is the benefit of
having both options?

> All the actions are defined inline. This is the most common use-case.

Hm. Why are classifiers and actions treated differently? Perhaps some
discussion of the design decisions somewhere in the document would be
useful.

/js

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From: "Aseem Choudhary (asechoud)" <[email-masked]>
Date: Tue, 19 May 2015 22:49:18 +0000

>defined in a separate YANG model?

[AC] OK, I see the point you are making, but there are some changes
regarding it in next version which will alleviate your concern.
>perspective, this sounds like extra cost. So what is the benefit of

[AC] There are pros and cons of defining either way: When defined as a
separate template, it becomes reusable objects. Any change in the object
updates the referencing objects too.
     While when defined inline, it is local change only. Any modification
has to be done on every instance.
    There are use-cases where users may use template and others where they
define inline. There are vendors which support either/or/both. Also,
Inline is defined as a feature.

>discussion of the design decisions somewhere in the document would be

[AC]  Actions are typically not reusable objects. Like metering rate or
RED thresholds are specific values vs classification of voice, video or
data.
      I will take this point of adding to the document.