[Ibnemo] 答复: [Nfvrg] 答复: Defining a Common Model for intent

[Xiayinben <[e-mail]>]

I agree this ☺

Yinben
发件人: Susan Hares [mailto:[e-mail]]
发送时间: 2015年6月9日 6:51
收件人: Xiayinben; 'Natale, Bob'; Zhoutianran; zhangyali (D); 'PEDRO ANDRES ARANDA GUTIERREZ'; [e-mail]
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主题: RE: [Nfvrg] 答复: [Ibnemo] Defining a Common Model for intent

Yinben:

After thought and Diego’s differentiation between security role and abstract role – I agree we should focus on the abstract role.  As Pedro suggested, the roles may have recursion within the intent (object, result, operation).   Let’s see what we can find that is common among two different examples.

Example 1: Provider’s provider – Intent: Carry AS 2 traffic (sub-role load balance across AS1-AS2 connections).
Example 2: Enhanced services Data Center Services – Network Access, mail cleaning in DPI, firewall

Does this seem like a good idea?
Sue


From: Xiayinben [mailto:[e-mail]]
Sent: Friday, June 05, 2015 11:07 AM
To: Susan Hares; 'Natale, Bob'; Zhoutianran; zhangyali (D); 'PEDRO ANDRES ARANDA GUTIERREZ'; [e-mail]<mailto:[e-mail]>
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Subject: 答复: [Nfvrg] 答复: [Ibnemo] Defining a Common Model for intent

Sue,

The meaning of what I said “intent of different roles are not mutually exclusive” actually is that we don’t need care the relationship between  two roles.
Maybe they are mutually exclusive and maybe they are overlap. That doesn’t matter.
I think our target is defining a group of intent for a role. Our focus is what this role really cared about. It should not be impacted by other roles.
But policy continuum, it seems it considers much about mapping high level policy to low level. This design of implementation impacts the definition of each layer’s content.  It creates impact between each layer.
I think the consideration about “distance” restrict the consideration about “expression”. So I prefer to decouple those two topics.
If we focus on what intent should be, we should not be impacted by implementation method.

BTW, thanks for your example, let me try to understand how to classify simple intent, intent with context and complex intent.

Yinben
发件人: Susan Hares [mailto:[e-mail]]
发送时间: 2015年6月5日 0:36
收件人: Xiayinben; 'Natale, Bob'; Zhoutianran; zhangyali (D); 'PEDRO ANDRES ARANDA GUTIERREZ'; [e-mail]<mailto:[e-mail]>
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主题: RE: [Nfvrg] 答复: [Ibnemo] Defining a Common Model for intent

Yinben:

I thought about your answer here over-night.  If the intent of different roles is not mutually exclusive, then either the intent is a complex structure or the role is context.

If my intent is to buy pants, then the intent is simple.
If the role is to pants shopping at the closest mall where mall is defined as many stores, then the intent is complex since it has context and constraints.   The role of shopping in closest mall requires determining the network connection to the local mall.

Similarly, if the AS 1 wants to be a provider for other provides – this is a simple intent (AS 1 is a provider’s provider).
If an AS 1 wants to be a provider for AS 2, it is a intent with context (AS1 is network AS2’s provider).
If AS2 wants to load share traffic to AS2, it is complex intent

a)      AS1 is AS2’s provider

b)      AS 1 is load sharing traffic to AS 2 along all ports.

These roles overlap because they are complex intent rather than pure unspecified intent.  Does this example help you understand my view of simple intent, complex intent, and intent with context.

Sue

From: Nfvrg [mailto:[e-mail]] On Behalf Of Xiayinben
Sent: Wednesday, June 03, 2015 11:54 AM
To: Natale, Bob; Zhoutianran; Susan Hares; zhangyali (D); 'PEDRO ANDRES ARANDA GUTIERREZ'; [e-mail]<mailto:[e-mail]>
Cc: [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>
Subject: [Nfvrg] 答复: [Ibnemo] Defining a Common Model for intent

Hi Bob,

In my understanding,  “policy continuum” is based on layer structure.
A characteristic of layer structure is mutually exclusive between layers.
But the intent of different roles are not mutually exclusive.
Do you think this is make sense?

Yinben

发件人: Nfvrg [mailto:[e-mail]] 代表 Natale, Bob
发送时间: 2015年6月3日 22:45
收件人: Zhoutianran; Susan Hares; zhangyali (D); 'PEDRO ANDRES ARANDA GUTIERREZ'; [e-mail]<mailto:[e-mail]>
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主题: Re: [Nfvrg] [Ibnemo] Defining a Common Model for intent

Hi Terence,

As Bert has noted on a related thread today, it is sensible to focus on intent expression at the “top” layer first.

However, work on that should be cognizant of two things:
- Who/what are the intended consumers of such expressions?
- What is the “distance” from the top level intent expressions to executable actions that affect network behavior?

Those two things are interrelated and captured in the policy continuum concept and construct … you can conceptualize them differently, resulting in different constructs, and that is fine … but you cannot escape them. Any attempt to escape them will result, at best, in a beautiful language that will never be spoken in an operational context.

Avanti,
BobN

From: Ibnemo [mailto:[e-mail]] On Behalf Of Zhoutianran
Sent: Wednesday, June 03, 2015 5:19 AM
To: Natale, Bob; Susan Hares; zhangyali (D); 'PEDRO ANDRES ARANDA GUTIERREZ'; [e-mail]<mailto:[e-mail]>
Cc: [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>
Subject: Re: [Ibnemo] Defining a Common Model for intent


Hi Bob,

I agree with you that the intent expression is the first important step. And that’s what we are going to do.
I think in this discussion group we will focus on the top layer intent. As I posted in the email on the “role based intent”, there will be only one intent layer and I do not think the “policy continuum” works or necessarily applied here. In contrast I would like a flat intent expression with many ways for both pure intent and the constrained intent.

Regards,
Terence

From: Ibnemo [mailto:[e-mail]] On Behalf Of Natale, Bob
Sent: Wednesday, June 03, 2015 1:15 PM
To: Susan Hares; zhangyali (D); 'PEDRO ANDRES ARANDA GUTIERREZ'; [e-mail]<mailto:[e-mail]>
Cc: [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>
Subject: Re: [Ibnemo] RE: Defining a Common Model for intent

Hi Sue,

Yes, the Formal Model paper is a very good source, but should be augmented with a few others for a more complete understanding.

And it is very important to note that the policy continuum is not _my_ model … it is (to the best of my knowledge) John Strassner’s creation and I generally recommend Chap. 9, Examples of Using the Policy Continuum, in his book on Policy-Based Network Management: Solutions for the Next Generation (2004) as an essential source.

[Apologies for possibly rambling a bit in what follows … I am not an active contributor and I hate to take up the time of those who are just because I have a few minutes to post, but since Sue asked….]

I would note that the specific layer labels used in the policy continuum literature should not be considered absolute … i.e., other formulations (with more or (ideally) fewer layers) are possible, with different labels, denoting (e.g.) some domain-, marketplace-, or business model-specificity.

The key issue is the number and nature of the translations necessary from a statement of intent at the “top” layer to a set of actions at the “bottom” layer that serve to realize the intent. In John’s policy continuum the top layer is the “Business” layer and we might see policy expressions like “Optimize traffic flows for fairness to all active users” or “Optimize traffic flows for priority based on user account type” (e.g., the proverbial Platinum, Gold, Silver, Bronze casting). Those are deliberately stark examples … in reality, the Business layer promulgates enormous numbers of policies often overlapping and “frictional” … but take either stark example and consider how many translations it would take to result in a conforming set of actions in large-scale network of diverse devices, services, protocols, (and a very large)  etc. In current technology (and for the foreseeable future, at my age at least!) at some point such statements of intent from the Business layer have to get translated to E-C-A type rules.

I recognize an intent-based policy expression by its distance from a set of expression (usually “rules”) that execute actions that realize the outcome stated in the intent-based expression. In that view, it’s not an absolute (i.e., the diverse views of the Policy Continuum hold) and it’s also possible to envision cases where expressions of intent can be “directly” implemented by a resource or set of resources. SDN is a step in the direction of (1) reducing the number of translations necessary for a large class of intent-based policy expressions and (2) virtualizing the implementation actions from the perspective of the “upper” layers of the policy continuum (or continua).

So, SDN and the ecosystem of changes around it represent  a big opportunity to make progress on rationalizing policy management across the layers of the policy continuum. A necessary first step is having useful standards for policy-expressions from the “top” layer – and they typically talk in intent-based policy expressions there.

Btw, I presume that IBNemo* contributors are also following John’s work in the SUPA area as well … very important that these efforts are totally complementary and synergistic, IMHO.

[* - Is it “IBNemo”, “ibnemo”, “IB-nemo” or something else? … I see it written all of those ways, and possibly more....]

Avanti,
BobN

From: Susan Hares [mailto:[e-mail]]
Sent: Tuesday, June 02, 2015 6:26 PM
To: Natale, Bob; 'zhangyali (D)'; 'PEDRO ANDRES ARANDA GUTIERREZ'; [e-mail]<mailto:[e-mail]>
Cc: [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>
Subject: RE: [Ibnemo] RE: Defining a Common Model for intent

Bob:

Thank you for The Policy Continuum – A Formal Model (Steven Davy , Brendan Jennings and John Strassner). Is this the one you stated we should read?

http://www.tssg.org/files/archives/2007_MACE_SDavy_Jennings_final.pdf

Davy, Jenning and Strassner.  In this continuum it suggests there are descending levels at: business, system (device and technology independent), administrator (device independent, technology dependent), device (device and technology specific), and instance (specific MIB, PIB, and CLI).  The system level is what Yali and Yinben have talked about when they speak about a connection from London to Beijing.  The administrator is a level of an L3VPN network with many devices.   I have suggested a few more layers that related in a gap analysis for I2NSF.  These layer match what the IETF is doing in the yang modules.

+--------------------------------------------+
|Application Network Wide: Intent            |
+--------------------------------------------+
|Network-wide level: L3SM L3VPN service model|
+--------------------------------------------+
|Device level: Protocol Independent: I2RS    |
| RIB, Topology, Filter-Based RIB            |
+--------------------------------------------+
|Device Level: Protocol Yang modules         |
| (ISIS, OSPF, BGP, EVPN, L2VPN, L3VPN, etc.)|
+--------------------------------------------+
| Device level: IP and System: NETMOD Models |
| (config and oper-state), tunnels           |
+--------------------------------------------+

Did I understand your policy continuum?

The policy continuum paper states three axioms:
“1) A policy may exist at any level of the continuum without the requirement of being associated to policies at other continuum levels.
2) A policy may reference a set of lower level policies.
3) A policy may be associated to more than one higher level policy”

Can you explain your comment:

“the “need” for multiple intermediate E-C-A translations at multiple layers of the policy continuum has heretofore been a major impediment to progress on policy-based management, IMHO.”

Does this come out of the formal language in the paper?

Sue

From: Natale, Bob [mailto:[e-mail]]
Sent: Tuesday, June 02, 2015 1:25 AM
To: zhangyali (D); PEDRO ANDRES ARANDA GUTIERREZ; Susan Hares; [e-mail]<mailto:[e-mail]>
Cc: [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>
Subject: RE: [Ibnemo] RE: Defining a Common Model for intent

With all due respect:

1. I would recommend that anyone working on this topic, if he/she has not done so already, understand the “policy continuum” construct … a web search for ‘"policy continuum" Strassner’ will identify a good set of sources to start from for the network management domain.

2. Intents are statements of objectives or goals … they tend  to originate at the “higher” levels of the policy continuum … at some point (at “lower” layers of the policy continuum) they are translated to E-C-A type rules (more deterministic than intents)  for execution … much normally happens in between.

3. Designing solutions that minimize the number of translations between the statement of intent and the execution rules is essential .. and _possibly_ enabled by contemporary technologies via which “higher” layer intents can be translated to “lower” layer intents before hitting the ultimate E-C-A execution layer. This is a highly speculative statement on my part. But the “need” for multiple intermediate E-C-A translations at multiple layers of the policy continuum has heretofore been a major impediment to progress on policy-based management, IMHO.

The “with all due respect” aspect refers to the fact that the work that the active contributors to this thread are doing is very positive even if none of my comments are acted upon.

Avanti,
BobN

From: Ibnemo [mailto:[e-mail]] On Behalf Of zhangyali (D)
Sent: Monday, June 01, 2015 11:52 PM
To: PEDRO ANDRES ARANDA GUTIERREZ; Susan Hares; [e-mail]<mailto:[e-mail]>
Cc: [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>
Subject: [Ibnemo] 答复: Defining a Common Model for intent

Hi Pedro,

Thanks for reviewing the draft and giving modification.

The question you have mentioned is a very important point for the abstraction of intent model. Maybe we can propose the transport market as a analogy.

1.       A customer wants to transport his goods from A to B. So his intent is getting his goods from A to B without carrying about how to do it. Then his intent is transferred to the transportation system.

2.       This system analyzes customer’s requirement, and choose a suitable way to complete the requirement. For example, the system choose truck as the means. So the intent of transportation system is transferring the goods with truck.

3.       The driver of this truck analyze the path from A to B, and choose a most appropriate path to complete this order which will save more time. So  the intent of driver may be transferring the goods with the least time. Then the driver will start the engine, step on the gas, etc.

From this analogy, the ultimate effect is the same, namely, transfer the goods from A to B. But the specific intent of different roles has some differences which depends on user’ role, knowledge, responsibility, etc. For example, transportation system is responsible for transporting goods, and he know the various ways. So he can form his intent by rendering the upper customer’s intent.

Supposing we divide users into different layers according to the implementation series, users in upper layer expresses his intent as what he want without having the knowledge about how to do it. Then the how procedure will be transferred to what in the lower layer according to knowledge and context. These transfer procedure lead to the completion of requirement. Same with the example in draft. Although the ultimate effect is same, the focus is different which will bring out the differentiation of intent.

This is just my immature opinion about intent. Do you think the differentiation of intent to complete the same thing is important and reasonable?

Best Regards,

Yali

发件人: PEDRO ANDRES ARANDA GUTIERREZ [mailto:[e-mail]]
发送时间: 2015年6月1日 17:15
收件人: Susan Hares; [e-mail]<mailto:[e-mail]>
抄送: [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>
主题: Re: [Ibnemo] Defining a Common Model for intent

Hi,

A small clarification proposal for draft https://datatracker.ietf.org/doc/draft-xia-ibnemo-icim/ .

In section 2.4, I would leave the following as a paragraph

For example, in the network area the intent of end-users could be

safe connectivity between two sites which a technology independent

and device independent requirement. For business-based network

designers, the network connectivity can be selected which is device-

independent but technology specific. An example of the business-based

technology is the L3VPN.

And change:

For network administrators, intent can be

specific operations on a set of devices such as configuring IP

addresses on network servers in a data center.
To


For network administrators, intent can be <new>defining a network topology like a router connected to a firewall, connected to a load balancer and this to two L2 networks where WWW servers sit or specifying the</new> operations on a set of devices such as configuring IP addresses on network servers in a data center.



Rationale behind this is again, that intent should be anything that is invariant and that expresses what a network operator/administrator may need to do, as opposed to how he would do that, i.e. The router is a HW device from vendor X or a virtual machine running a specific routing daemon over a given data-path implementation.

Best, /PA
---
Dr. Pedro A. Aranda Gutiérrez

Technology Exploration -
Network Innovation & Virtualisation
email: pedroa d0t aranda At telefonica d0t com
Telefónica, Investigación y Desarrollo
C/ D. Ramón de la Cruz,84
28006 Madrid, Spain

Fragen sind nicht da, um beantwortet zu werden.
Fragen sind da, um gestellt zu werden.
Georg Kreisler

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