Network Working Group J. Bi Internet Draft Tsinghua Univ. Intended status: Standard Track Q. Sun Expires: May 2016 C. Xie China Telecom November 4, 2015 Declarative Policy Model draft-bi-declarative-policy-00 Abstract This document describes a declarative model for traffic steering policies in Distributed Data Center (DDC) scenarios. The policy model is a specific data model for traffic steering using VPN technology. It helps the service management in Simplified Use of Policy Abstractions (SUPA) to model the policy (a set of constraints and rules) that defines how a VPN service is monitored by bandwidth and managed during its lifecycle. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on April 30, 2015. Bi, et al. Expires May 3, 2016 [Page 1] Internet-Draft Declarative Policy Model November 2015 Copyright Notice Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction .................................................2 2. Conventions used in this document ............................3 3. Policy Based Service Management Framework ....................3 4. declarative Based Policy Configuration Modules ...............4 4.1. Declarative Based Policy Framework ......................4 4.2. Declarative Based Policy Model ..........................6 5. declarative Policy Applications in DDC services ..............9 5.1. Policy Based Traffic Steering Case study ................9 5.2. Declarative Based Policy Enforcement ...................11 6. Security Considerations .....................................13 7. IANA Considerations .........................................13 8. Acknowledgments .............................................13 9. References ..................................................13 9.1. Normative References ...................................13 9.2. Informative References .................................14 1. Introduction In order to support the DDC service with VPN connection as well as new services, it brings new requirements for both network providers and service providers. Rapid uptake of new services requires dynamic service provisioning capabilities in the service management. This is achieved using policies that can be created by the operators once and the service management refers to these policies to infer how a given service needs to be provisioned considering the current state of the network. Bi, et al. Expires May 3, 2016 [Page 2] Internet-Draft Declarative Policy Model November 2015 In SUPA framework, network policy is a predefined rule or a set of rules that the service management use to map the service to the lower level network infrastructures. Meanwhile, DDC service which is mainly relied on VPN [RFC4110] needs policy based management and controlling capability from the service management systems to facilitate the service deployment both inter data centers and within data center. This document introduces YANG [RFC6020] [RFC6021] data models for SUPA configuration. Such models can facilitate the standardization for the interface of SUPA, as they are compatible to a variety of protocols such as NETCONF [RFC6241] and [RESTCONF]. Please note that in the context of SUPA, the term "application" refers to an operational and management applications employed, and possibly implemented, by an operator. The policy model is based on the first example - DDC services. With respect to the scope, defining an information model for the policy exchange between the policy manager and policy agent and a corresponding data model based on yang to support specific DDC service use case is initial goal of this document. The protocol specific aspects are deferred to respective implementations. Also certain foundational concepts of the model are intentionally left open to enable future extension. Here the traffic steering policy in DDC use case provides a concrete example for a specific network technology and service, as what constitutes a policy could itself vary depending on the context where it is used, e.g. there could be tenant specific policies, site specific, network domain specific etc. 2. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. In this document, these words will appear with that interpretation only when in ALL CAPS. Lower case uses of these words are not to be interpreted as carrying [RFC2119] significance. 3. Policy Based Service Management Framework Figure 1 illustrates the network configuration model which contains several modules for specific services such as VPN management. Basically, service model is to define the creation and configuration of the VPN service, while the policy model is more Bi, et al. Expires May 3, 2016 [Page 3] Internet-Draft Declarative Policy Model November 2015 focused on the adjustment or optimization of the flow path during the lifecycle of the VPN service based on the predefined policy. +------------------------------------------+ | Generic Policy Model | | | | +------------+ +---------------+ | | | ECA Policy | | Declarative | | | | Data Model | | Policy Model | | | +------------+ +---------------+ | +------------------------------------------+ Figure 1: Overview of configuration model structure 4. Declarative Based Policy Configuration Modules In this section, a policy model is defined with an application for traffic steering between data centers are provided to illustrate how to use the policy model. The policy model and policy configuration are based on a set of specific network services and the framework of SUPA [SUPA-framework]. On the other hand, the policy model should be working on the orchestration level which is above network element and below OSS level based on the YANG model classification in [draft-bogdanovic-netmod-yang-model classification-02] 4.1. Declarative Based Policy Framework Desired state: The description of the final state of the system, in another word, the goal or the declarative of the policy management. In SUPA scope, it consists of constraints. Behavior constraint: a set of constraints to limit the possible operations or states in processing the policy goal to achieve the final state. Each constraint is expressed in the form of logical , numeric and set relations which use service objects defined in service model. Note that event, condition, and action can each be made up of Boolean clauses +--------------------------+ | PolicyRuleMetaData | Bi, et al. Expires May 3, 2016 [Page 4] Internet-Draft Declarative Policy Model November 2015 +--------------------------+ | +--------------+ | PolicyRule | +--------------+ | ---------------------- | | +--------------+ +----------------+ | ECA Policy | | Declarative | | Model | | Policy Model | +--------------+ ++---+-----------+ | | --------------------- | | | +-----------------+ +---------------------+ | Desired State | | Behavior Constraint | +-----------------+ +---------------------+ Figure 2: Overview of information declarative based policy model Bi, et al. Expires May 3, 2016 [Page 5] Internet-Draft Declarative Policy Model November 2015 module: SUPA-declarative-policy +--rw policy-set +--rw set-name string +--rw set-type enumeration +--rw applicable-service-type enumeration +--rw policy-rule-metadata uint32 +--rw policy-rule +--rw rule-name string +--rw rule-type enumeration +--rw policy-rule-priority? uint8 +--rw policy-validity-period | +--rw start? yang:date-and-time | +--rw end? yang:date-and-time | +--rw duration? uint32 | +--rw periodicity enumeration +--declarative-policy-rule +--rw desired-state | +--rw constraint string | +--rw constraint-priority uint8 +--rw behavior-constraint +--rw constraint string +--rw constraint-priority uint8 4.2. declarative Based Policy Model file "ietf-declarative-policy@2015-10-10.yang" module ietf-declarative-policy { namespace "urn:ietf:params:xml:ns:yang:ietf-declarative-policy"; // replace with IANA namespace when assigned prefix policy; import ietf-inet-types { prefix inet; } import ietf-yang-types { prefix yang; } organization "IETF"; contact "Editor: "; description "This YANG module defines a component that describing the ddc policy model for monitoring and optimizing tenant's DC (data center) services that are deployed in multiple data centers. Bi, et al. Expires May 3, 2016 [Page 6] Internet-Draft Declarative Policy Model November 2015 Terms and Acronyms DDC: Distributed Data Center L2VPN: Layer 2 Virtual Private Network L3VPN: Layer 3 Virtual Private Network"; revision 2015-10-10 { description "Initial revision."; reference " Network Policy YANG Data Model "; } container policy-set{ description "Policy set."; leaf set-name { type string; description "The name of the policy."; } leaf set-type { type enumeration { enum local { description "local"; } enum globe { description "globe"; } } } leaf policy-rule-metadata { type uint32; } container policy-rule { description "Declarative policy rule."; leaf rule-name { type string; description "Policy rule name."; } leaf rule-type { type enumeration { enum local { description "local"; } Bi, et al. Expires May 3, 2016 [Page 7] Internet-Draft Declarative Policy Model November 2015 enum globe { description "globe"; } } } leaf policy-rule-priority { type uint8; } container policy-validity-period { description "The working period of the policy."; leaf start { type yang:date-and-time; } leaf end { type yang:date-and-time; } leaf duration { type uint32; } leaf periodicity { type enumeration { enum daily { description "daily"; } enum monthly { description "monthly"; } } } } container Declarative-policy-rule { description "Define declarative policy rule"; container desired-state { description "Describe desired state."; leaf constraint { type string; description "Define the constraint."; } leaf constraint-priority { type uint8; } } Bi, et al. Expires May 3, 2016 [Page 8] Internet-Draft Declarative Policy Model November 2015 container behavior-constraint { description "Describe the constraint on action behavior."; leaf constraint { type string; description "Define the constraint."; } leaf constraint-priority { type uint8; } } } } } } 5. Declarative Policy Applications in DDC services 5.1. Policy Based Traffic Steering Case study Traffic Steering use case description: In one set of links, keep all link utilization below 70%. If some flows need to move to other link, keep Gold user flows untouched. After analyze above case, we structure the description as following: Related objects: links flow(usertype) Goal all link utilization < 70% constraint: keep Gold user flows untouched The service model of this use case: Bi, et al. Expires May 3, 2016 [Page 9] Internet-Draft Declarative Policy Model November 2015 +--------------+ +--------------+ | Link +--------------+ Flow | +--------------+ m n +--------------+ | uti: float | | bw:int | | phybw: int | | srcip:IPAddr | | | | destip:IPAddr| | | | userlevel: | | | | enum(Gold, | +--------------+ | Normal) | | | +--------------+ Figure 3. service model of traffic steering policy use case Link attribute Uti: link bandwidth utility Phybw: physical bandwidth of the link Flow attribute bw: the bandwidth of the flow srcip,destip: the source and dest ip address of the flow userlevel: the user's service level of the flow, it can be gold or normal. Bi, et al. Expires May 3, 2016 [Page 10] Internet-Draft Declarative Policy Model November 2015 +--------------+ +--------------+ | Policy |-----|Rule(abstract)| +--------------+ +--------------+ A +-------+ | +-------+------+ | Goal-rule | +--------------+ A V V ----+ subclass +-------+ +------+ | | V +-------------+ +--------------+ ----+ composition | Goal | | behavior | +-------------+ | constraint | +--------------+ Figure 2. policy model of traffic steering policy use case 5.2. Declarative Based Policy Enforcement Based on the service model and policy model traffic steering use case introduced in above section. This section introduce an example of policy framework and briefly illustrate how to enforce the declarative based policy. +---------------------------------------+ | SUPA policy service API | | | +--------|--------------------|---------+ | | /-------v--------\ /-------v--------\ | service model | | Policy | | | | repository | \-------|--------/ \-------|--------/ +------------+ | /----------\ +---v-------v---------+ | context |----->| Policy Engine | | data | | | \----------/ | +-----+ +-------+ | | | ECA | | Goal | | /----------\ | | | | | | | Event |----->| +-----+ +-------+ | | data | | | \-----A----/ +-----------|---------+ Bi, et al. Expires May 3, 2016 [Page 11] Internet-Draft Declarative Policy Model November 2015 | | +-------------+ +-------------v---------+ | Collector | | Action Schedular | +-----A-------+ +-------------|---------+ |event v action Figure 3. declarative policy framework as an example Figure 3 shows the example framework. In the framework, the policy engine take the key role who translate the declarative policy to lower layer actions. The policy engine is problem domain agnostic. It depends service model and policy model to operate on problem domains. Following give some brief illustration around the traffic steering use case that how the policy engine do declarative based policy enforcement. First, to inject the capability of operating on traffic steering policy to the policy system, the guide model(see section 5.1) and the service mode(see section 5.1) is input to the system. Then, under some concrete traffic steering scenario, one user can express the declarative by transfer the desired state and constraint to the system. After verifying the policy language script against the service model and policy syntax, the policy framework will save the user's declarative policy in policy repository. When the policy is activated, the policy engine may get data from context data store, in this case, the data include the link, flow and there relationship information. The policy engine is guided by the guide model and user's declarative policy model, evaluate whether some selected data is compatible with the constraints and desired states. After finding out data, the policy engine will fill the tuples which is the result of the 'select' to the action container, in this case is move(flow:Flow,tolink:Link) Finally the policy engine output a list of actions such like move(flow1,link3) move(flow2,link5) move(flow4,link2) The flow1,flow2,flow4,link3,link5,link2 all comes from context data store as seen in figure 4 Bi, et al. Expires May 3, 2016 [Page 12] Internet-Draft Declarative Policy Model November 2015 The policy engine even does not know what 'move' is, but the system can map the abstract move action to a concrete function at lower layer to perform the movement. The collecting context data, making decision and output action circle may perform one or multiple times to change the traffic steering system to a new steady state and meet the user's goal. 6. Security Considerations TBD 7. IANA Considerations This document has no actions for IANA. 8. Acknowledgments This document has benefited from reviews, suggestions, comments and proposed text provided by the following members, listed in alphabetical order: Junru Lin, Felix Lu, Yiyong Zha, and Min Zha. 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, October 2010. [RFC6021] Schoenwaelder, J., "Common YANG Data Types", RFC 6021, October 2010. [RFC3272] Awduche, D., Chiu, A., Elwalid, A., Widjaja, I., and X. Xiao, "Overview and Principles of Internet Traffic Engineering", RFC 3272, May 2002. Bi, et al. Expires May 3, 2016 [Page 13] Internet-Draft Declarative Policy Model November 2015 9.2. Informative References [SUPA-framework] C. Zhou, L. M. Contreras, Q. Sun, and P. Yegani, " The Framework of Shared Unified Policy Automation (SUPA) ", IETF Internet draft, draft-zhou-supa-framework, January 2015. [SUPA-problem-statement] G. Karagiannis, Q. Sun, Luis M. Contreras, P. Yegani, and JF Tremblay, "Problem Statement for Shared Unified Policy Automation (SUPA)", IETF Internet draft, draft-karagiannis- supa-problem-statement, January 2015. [SUPA-DDC] Y. Cheng,and JF. Tremblay, "Use Cases for Distributed Data Center Applications in SUPA", IETF Internet draft, draft- cheng-supa-ddc-use-cases, January 2015. [RESTCONF] Bierman, A., Bjorklund, M., Watsen, K., and R. Fernando, "RESTCONF Protocol", draft-ietf-netconf-restconf (work in progress), July 2014. [POLICY MODEL] Z. Wang, L. Dunbar, Q. Wu, "Network Policy YANG Data Model" draft-wang-netmod-yang-policy-dm, January 2015. Authors' Addresses Jun Bi Tsinghua University Network Research Center, Tsinghua University Beijing 100084 China Email: junbi@tsinghua.edu.cn Qiong Sun China Telecom No.118 Xizhimennei street, Xicheng District Beijing 100035 P.R. China Email: sunqiong@ctbri.com.cn Chongfeng Xie China Telecom No.118 Xizhimennei street, Xicheng District Beijing 100035 P.R. China Email: xiechf@ctbri.com.cn Bi, et al. Expires May 3, 2016 [Page 14]