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

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

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]
Cc: [e-mail]; [e-mail]
Subject: RE: [Ibnemo] 答复: 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]
Cc: [e-mail]; [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]
抄送: [e-mail]; [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/> 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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