Re: [Ibnemo] Defining a Common Model for intent

["Susan Hares" <[e-mail]>]

Bert: 

Ok - give me an example from your context.  I tried BGP first,  general systems theory second, and wind 3rd.     The equations are: 

User --> intent --> context
Intent = object, results, constraint 

Where do roles fit in these equations? 
BGP:  
user (provider) --> intent (be providers provider) --> context (bgp infrastructure)
Intent (AS2 be provider's provider) --> object (AS1 provider), results (pass AS1 providers traffic), constraint (load-balance across all circuits connect to AS2). 

Now - what is a role-based intent or policy for BGP?  I'll welcome a practical answer. 

Sue 

-----Original Message-----
From: Bert Wijnen (IETF) [mailto:[e-mail]] 
Sent: Thursday, June 04, 2015 2:56 PM
To: Susan Hares; 'Zhoutianran'; 'Natale, Bob'; 'zhangyali (D)'; 'PEDRO ANDRES ARANDA GUTIERREZ'; [e-mail]
Cc: [e-mail]; [e-mail]
Subject: Re: [Ibnemo] Defining a Common Model for intent

It may be jsut me, but adding "pure" intent and "impure" intent and jetstreams etc, it does just become more vague for me.

See also inline

On 04/06/15 20:41, Susan Hares wrote:
>
> Tianran/ Terrence:
>
> Instinctively, I believe that role-based intent provides an ability to 
> define and classify intent.  I know how to identify the role 
> relationships, and the actions between roles.  However, I still do not really understand classify the relationship between intent and roles.
>
> My concern is that we are looking at general system theory where certain things are first order changes and other things are 
> second-order changes.   A first order change is like the wind blowing.  A second order change is when the upper atmosphere jet 
> stream changes causing a whole shift in weather patterns.
>
> If we classify intent by roles, will we find that roles are the “jet 
> stream” that pushes a lot of intent.  Or will we find some “pure” intent classes are the jet stream that pushes a lot of intent or “jet stream” ?
>
I cannot make heads or tails from that sentence. Again, it may be just me.

Bert
>
> Best wishes,
>
> Sue
>
> *From:*Zhoutianran [mailto:[e-mail]]
> *Sent:* Thursday, June 04, 2015 2:36 AM
> *To:* Natale, Bob; Susan Hares; zhangyali (D); 'PEDRO ANDRES ARANDA 
> GUTIERREZ'; [e-mail]
> *Cc:* [e-mail]; [e-mail]
> *Subject:* RE: [Ibnemo] Defining a Common Model for intent
>
> Hi Bob and Sue,
>
> The role based intent gives the methodology to define and classify 
> intent. I think both Bob and me realize the identifying roles is important. And yes, it’s on the top.
>
> Of course, intent need to be implemented. We can do this compilation 
> layer by layer, i.e., like policy continuum, from goal to fitness to 
> ECA to …. By the way, it seems in policy continuum, everything is policy, and an intent can be compiled by policies all the way to device instructions. Please correct me if it is not.
>
> My idea is:
>
> On one hand, I would like a flat intent expression with many ways for both pure intent and the constrained intent.
>
> On the other hand, I think the intent can be implemented by many 
> existing layered functions like the figure I showed. And a cross layer design will make the intent implementation more flexible.
>
> I am not going to create concepts but an operational solution. I think 
> policy continuum is an option for intent implementation, but it’s not mandatory cannot escape.
>
> Best Regards,
>
> Terence
>
> *From:*Natale, Bob [mailto:[e-mail]]
> *Sent:* Wednesday, June 03, 2015 10:45 PM
> *To:* 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:* RE: [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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