I2RS working group S. Hares Internet-Draft Hickory Hill Consulting Intended status: Standards Track Q. Wu Expires: August 17, 2014 Huawei February 13, 2014 An Information Model for Network policy draft-hares-i2rs-info-model-policy-01 Abstract This document introduces an information model for network policies. This model operates as policy model that can be linked to other information model such as the I2RS RIB information model. Some applications that utilize the services of I2RS client may require specific set of data in response to network events or conditions based on pre-established rules. In order to reduce the data flow through the network, the I2RS client needs to signal the I2RS agent to filter some of the collected data or events prior to transmission, or group the data prior to transmission to the i2rs client. This functionality is necessary to meet the requirements i2rs enabled services which include service-layer routing improvements, and control of traffic flows and exit points. The information model is based on extensible information model for representing policies, for example, the Policy Core Information Model (PCIM) (RFC3060), and an extension to this model to address the need for QoS management, called the Quality of Service (QoS) Policy Information Model (QPIM)(RFC3644). 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). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on August 17, 2014. Hares & Wu Expires August 17, 2014 [Page 1] Internet-Draft IM for policy February 2014 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 1.1. Currently Out of Scope for I2RS . . . . . . . . . . . . . 4 2. Definitions and Acronyms . . . . . . . . . . . . . . . . . . 4 3. Network Policy Model Overview . . . . . . . . . . . . . . . . 5 4. Network Policy Information Model . . . . . . . . . . . . . . 7 4.1. The Policy Group Component . . . . . . . . . . . . . . . 7 4.2. The Network-Policy Rule Component . . . . . . . . . . . . 10 4.3. The Local Config Component . . . . . . . . . . . . . . . 12 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 6. Security Considerations . . . . . . . . . . . . . . . . . . . 15 7. Informative References . . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 1. Introduction The Interface to the Routing System (I2RS) provides read and write access to the information and state within the routing process within routing elements. The I2RS client interacts with one or more I2RS agents to collect information from network routing systems. Processing of collected information at the I2RS agent may require the I2RS Agent to filter certain information or group pieces of information in order to reduce the data flow through the network to the I2RS client. Some applications that that utilize the services of I2RS client may also wish to require specific data in response to network events or conditions based on pre-established rules. This functionality is necessary to meet the requirements of i2rs enabled services which include service-layer routing improvements, and control of traffic flows and exit points. Hares & Wu Expires August 17, 2014 [Page 2] Internet-Draft IM for policy February 2014 This document introduces a basic information model for network policies. This policy model can be linked with other information models such as the I2RS RIB informational model [I-D.ietf-i2rs-rib-info-model] as a generic policy module. This basic policy model can be easily extended beyond the basic functions. The [I-D.ietf-i2rs-architecture] suggests that associated with the the i2RS RIB model there will be "Policy-based Routing (ACLs)" and RIB "policy controls". These basic policy functions can operate as part of this functional blocks providing the basic model for policy operators. This model can also be considered as the substance of the policy templates. The basic but extendable policy model is a product of the industry approach to I2RS. The initial I2RS work is focusing on the initial RIB module, and basic functions to make the initial RIB model function within real networks. Subsequent drafts will provide building blocks upon this policy model that can be used to create network functions. This information model leverages previous work done on extensible information model for representing policies, for example, the Policy Core Information Model (PCIM) [RFC3060] [RFC3060], and an extension to this model to address the need for QoS management, called the Quality of Service (QoS) Policy Information Model (QPIM) [RFC3644] [RFC3644]. Most policy within routing and forwarding systems has become hierarchical with individual specific policies being grouped as a set policy. The hierarchical policy rule definition enhances policy readability and reusability. Groups of network policies have labels to aid operational use. Named groups of policy are easily identified and reused as blocks. The information model contains the following three components: Policy Group Policy is described by a set of policy rules that may be grouped into subsets. A Policy group is used to provide a hierarchical policy definition that provides the model context or scope for sub-rule actions. The model context includes identity, scope, role, precedence, priority and security model. In a policy group policy rules and policy groups can be nested within other policy rules. Network-Policy Hares & Wu Expires August 17, 2014 [Page 3] Internet-Draft IM for policy February 2014 contains a generic network policy model. It can be thought of as a coherent set of rules to administer, manage, and control access to network resources and defines a network policy at its most general level of abstraction. It models aspects such as actions and conditions that constitute a policy element relationship, as well as operators contained in the both condition and action that can either be used to overwrite an old value of the variable or imply match relationship. Policies vary in level of abstraction, for example policy at parent level or policy at child level. The model therefore allows to show relationships between policies, as well as dependencies between condition and action across policy. Local Config defines information kept that kept in policy database that is leveraged by CLI, SNMP, NetConf. 1.1. Currently Out of Scope for I2RS An I2RS client may also interact with other elements of the policy and provisioning system to retrieve policy to transmit to an I2RS agent to be use in processing collected information, or to pass to policy information bases (PIBs) within the routing system. How the I2RS client interacts with the policy and provision systems is currently outside the scope of I2RS. I2RS architecture allows multiple I2RS Clients to communicate with the same agent I2RS agent, but requires that only one I2RS client has write control over one element. Specification on how the I2RS Clients handle multiple client interactions it out of scope at this time. The i2rs-architecture document specifies in section x.x that I2RS clients should avoid writing the same element. In the future, the I2RS WG may decide to specify these interactions. Therefore, this document's policy information allows for extensions that will allow multiple clients. 2. Definitions and Acronyms IGP: Interior Gateway Protocol Information Model: An abstract model of a conceptual domain, independent of a specific implementations or data representation CLI: Command Line Interface SNMP: The Simple Network Management Protocol NETCONF:The Network Configuration Protocol Hares & Wu Expires August 17, 2014 [Page 4] Internet-Draft IM for policy February 2014 RBNF: Routing Backus-Naur Form 3. Network Policy Model Overview I2RS needs its own implicit and explicit policy. This section provides an overview of the network policy model. The network policy model is defined by the following components, whose relationship is roughly depicted in the figure below. +-----------------------+ | Network-Policy | +-----------+-----------+ ^ /|\ | "extends" +-----------^-------------+ | Policy Set | +--+-------------------+--+ ^ ^ /|\ /|\ | "extends" | "extends" +--------^-------+ +-------^-------+ +------------+ | Policy Group | | Policy Rule |<----|Local Policy| +----------------+ +---------------+ +------------+ : : ......: :..... : : : : +---------V---------+ +-V-------------+ Hares & Wu Expires August 17, 2014 [Page 5] Internet-Draft IM for policy February 2014 | Policy Condition | | Policy Action | +-------------------+ +---------------+ : : : : : : .....: . :..... .....: . :..... : : : : : : +----V---+ +---V----+ +--V---+ +-V------++--V-----++--V---+ | Match | |Policy | |Policy| | Set || Policy ||Policy| |Operator| |Variable| |Value | |Operator||Variable|| Value| +--------+ +--------+ +------+ +--------++--------++------+ Figure 1: Overall model structure The policy group component defines the basic network policy Group model. In addition, the Network-policy component defines the basic network policy rule model. PolicySet, is introduced to provide an abstraction for a set of rules. It is derived from Policy, and it is inserted into the inheritance hierarchy above both PolicyGroup and PolicyRule. This reflects the additional structural flexibility and semantic capability of both subclasses. Policy Rule is represented by semantics "If Condition then Action", therefore condition and action comprise Policy Rule model. Condition models the elementary match operation " match ". Action models the elementary set operation. "SET TO ". In Condition model, the 'Match' operator is usually implied while in the action model, the 'Set' operator is explicitly used. The Local Config Component contains a set of local policy state related to I2RS operation that the I2RS agent controls. The local system's local policy state linked to a particular information base (E.g. I2RS RIB) may have a write scope that one or more clients may write. The same write scope with that of one or more clients using an agent. An agent must check to determine if a local configuration state overlaps with existing installed state. Hares & Wu Expires August 17, 2014 [Page 6] Internet-Draft IM for policy February 2014 4. Network Policy Information Model This section specifies the network policy information model in Routing Backus-Naur Form (RBNF, [RFC5511]). It also provides diagrams of the main entities that the information model is comprised of. 4.1. The Policy Group Component In order to provide hierarchical policy definition and associate policy rule with other constraint, the basic policy group model needs to be defined. The corresponding extensions are introduced in a component, whose structure is informally depicted in the following diagram. Hares & Wu Expires August 17, 2014 [Page 7] Internet-Draft IM for policy February 2014 +------------------------------------+ | Policy Group |.... +------------------------------------+ : * * * * * ^ : | | | | | :....: | | | | | | | | | | | | | | | +--------+ +--------+ +--------+| +-----------+ |Identity| | Role | |Priority|| |Policy Rule| +--------+ +--------+ +--------+| +-----------+ * * | * * * | | | | | | +--- | | +---+---+ | ++----+ | | | |Enabled| | |Usage| | | | +-------+ | +-----+ +-----+----+ +------+ | | | Resource | |Scope | | | +----------+ +------+ | | * * | +--+------+ | | +----+------+ |Mandatory| | | | Precedence| +---------+ | | +-----------+ | | +-----++-----+ | Read||Write| |Scope||Scope| +-----++-----+ Hares & Wu Expires August 17, 2014 [Page 8] Internet-Draft IM for policy February 2014 The basic information model works as follows: Within the policy group information model, hierarchy is used to model context or scope for the sub-rule actions. A policy group contains Identity, scope, priority,precedence, policy rule and policy group. Policy rule or policy group can be nested into policy group. Policy rule can inherit context from policy group as properties and also policy rule can have its own properties, eg., enabled, mandatory, usage properties. A more formal depiction in RBNF format follows below: ::= [] [] ::= | ::= | ::= <> ... The elements of the Policy Group information model are as follows: o Each policy group is captured in its own list, distinguished via a identity, role, priority, precedence. o A policy group has a certain role, such as resource or scope. A policy group can even have multiple roles simultaneously. The role, are captured in the list of "role" component. o A policy role has a certain Scope, such as read scope or write scope. A policy group can even have multiple scope simultaneously. The scope, or scopes, are captured in the list of "scope" components. o A policy has a certain priority, such as priority 0-255. A policy can only have one priority. The priority is captured in the list of "priority" component. o A policy rule can inherit properties (e.g., identity,role,priority, precedence) from policy group. A policy Hares & Wu Expires August 17, 2014 [Page 9] Internet-Draft IM for policy February 2014 rule also can have its own properties, e.g., enabled, mandatory, usage. o The policy, policy group elements can be extended with policy- specific components (policy-extensions, policy-group-extension respectively). 4.2. The Network-Policy Rule Component The following diagram contains an informal graphical depiction of the main elements of the information model: +----------------+ | Policy Rule |<... +----------------+ : * * : : | | :...: | | +---------+ +--------+ ...>|Condition|<.......| Action |<... : +---------+<.......+--------+ : : : * * : : :..... | : :... : | : +--------+...........: |Operator| +--------+ Roughly speaking, the basic information model works as follows: A policy rule contains conditions and actions. Each condition or each action in turn contains operator. A operator connects variable and value in the action or condition. Condition can map onto and be supported by other condition, while action can map onto and be supported by other actions. Policy rule can map onto other, policy rules. The information model for the Network-policy component is more formally shown in the following diagram. Hares & Wu Expires August 17, 2014 [Page 10] Internet-Draft IM for policy February 2014 ::= (...) ::= ( (...) [] ::= ( []) | ( []) ::= | ::= | ::= | ... ::= (...) [] [] ::= | | | ::= | ... ::= [ ] ::= | ... The elements of the Network-Policy Rule information model are as follows: o A policy can in turn be part of a hierarchy of policies, building on top of other policies. Each policy is captured in its own level, distinguished via a policy-identity. Hares & Wu Expires August 17, 2014 [Page 11] Internet-Draft IM for policy February 2014 o Policy rule inherit scope from policy group. A policy role has a certain Scope, such as read scope or write scope. A policy rule can even have multiple scope simultaneously. The scope, or scopes, are captured in the list of "scope" components. o Furthermore, a policy rule contains conditions and actions, each captured in their own list. o A condition contains a variable and a value and use a match operator, to connect variable with value. An examples of an operator might be a" IP ADDRESS AS RESOLVED BYDNS" or "Set to a member". Also, a condition can in turn map onto other condition in an underlay policy. This is captured in list"supporting- condition". o An action contains a variable and a value. An action uses Set operator to connect variable with value. Analogous to a node, an action can in turn map onto other actions in an underlay policy. This is captured in list "supporting-action". o The policy, condition, action and operator elements can be extended with policy-specific components (policy-extensions, condition-extension, action-extension and operator-extension respectively). 4.3. The Local Config Component The Local Config Component is the information links to the policy functions associated with a information model it is linked to. This component defines a set of groupings with auxiliary information required and shared by those other components. Since the I2RS RIB model is the only currently agreed upon model, an example from this model may be helpful. The I2RS RIB model contains a RIB definition of routing instance that has 0-N interfaces and 1-N RIBs. Each RIB contains a set of routes. This policy operates on the elements of I2RS RIB model by combining one of the elements defined in the I2RS RIB model (Routing instance 1, RIB 1, route- attribute) within the context of a policy rule. The [I-D.ietf-i2rs-architecture] shows this as the RIB Policy Controls that impact the policy routing. The I2RS agent may only collect information on this RIB. On Write, the RIB Policy Rules may determine what portion of the Policy-Based RIBs are altered to provide the early exit or service routing features needed by the I2RS client. The key benefit of this Policy Information Model is that it provides a common model of interactions of policy which can be saved as Hares & Wu Expires August 17, 2014 [Page 12] Internet-Draft IM for policy February 2014 templates, and then enacted for specific functions associated with another model. The policy element an identity, scope, role, and security model. This allows the specific element to be easily tailor to identified by operations, enable for specific operations (via scope and role), and at a correct security level. As the example demonstrates, this blends with the I2RS RIB model to set conditions and actions. Additional drafts will show that it provides other service routing. ::= (...) ::= () (...) ::= ( []) | ( []) ::= | ::= | ... ::= (...) [] [] ::= | | | ::= | ... ::= [] ::= | ... Hares & Wu Expires August 17, 2014 [Page 13] Internet-Draft IM for policy February 2014 The model extends the original network-policy model as follows: o A local policy rule can in turn be part of a hierarchy of policies, building on top of other policies. Each local configuration policy is captured in its own level, distinguished via a policy identity. o A local policy rule inherit scope from policy group. A local policy rule has a certain Scope, such as read scope or write scope. A local policy rule can even have multiple scope simultaneously. The scope, or scopes, are captured in the list of "scope" components. o Furthermore, a local policy contains conditions and actions, each captured in their own list. o A condition contains a variable and a value and use a match operator, to connect variable with value. An examples of an operator might be a" IP ADDRESS AS RESOLVED BYDNS" or "Set to a member". Also, a condition can in turn map onto other condition in an underlay policy. This is captured in list "supporting- condition". o An action contains a variable and a value. An action uses Set operator to connect variable with value. Analogous to a node, an action can in turn map onto other actions in an underlay policy. This is captured in list "supporting-action". o The local policy, condition, action and operator elements can be extended with policy-specific components (condition-extension, action-extension and operator-extension respectively). Drafts that specify examples for this blended I2RS model are: o An Traffic balancing using the I2RS RIB Model [draft-hares-i2rs- TE-exit-balance] o Utilizing BGP Information regarding Service Chaining [draft-hares- i2rs-bgp-chains] o Information model for service topology [draft-hares-i2rs-info- model-service-topo] o In future revision of I2rs, this may link to other I2RS information models or linked through the I2RS agent to things configured by the CLI, SNMP, or via the NETCONF interface. Hares & Wu Expires August 17, 2014 [Page 14] Internet-Draft IM for policy February 2014 5. IANA Considerations This draft includes no request to IANA. 6. Security Considerations TBD. 7. Informative References [I-D.atlas-i2rs-policy-framework] Atlas, A., Hares, S., and J. Halpern, "A Policy Framework for the Interface to the Routing System", draft-atlas- i2rs-policy-framework-00 (work in progress), February 2013. [I-D.ietf-i2rs-architecture] Atlas, A., Halpern, J., Hares, S., Ward, D., and T. Nadeau, "An Architecture for the Interface to the Routing System", draft-ietf-i2rs-architecture-01 (work in progress), February 2014. [I-D.ietf-i2rs-rib-info-model] Bahadur, N., Folkes, R., Kini, S., and J. Medved, "Routing Information Base Info Model", draft-ietf-i2rs-rib-info- model-01 (work in progress), October 2013. [I-D.white-i2rs-use-case] White, R., Hares, S., and A. Retana, "Protocol Independent Use Cases for an Interface to the Routing System", draft- white-i2rs-use-case-01 (work in progress), August 2013. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3060] Moore, B., Ellesson, E., Strassner, J., and A. Westerinen, "Policy Core Information Model -- Version 1 Specification", RFC 3060, February 2001. [RFC3644] Snir, Y., Ramberg, Y., Strassner, J., Cohen, R., and B. Moore, "Policy Quality of Service (QoS) Information Model", RFC 3644, November 2003. [RFC5394] Bryskin, I., Papadimitriou, D., Berger, L., and J. Ash, "Policy-Enabled Path Computation Framework", RFC 5394, December 2008. Hares & Wu Expires August 17, 2014 [Page 15] Internet-Draft IM for policy February 2014 [RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax Used to Form Encoding Rules in Various Routing Protocol Specifications", RFC 5511, April 2009. Authors' Addresses Susan Hares Hickory Hill Consulting 7453 Hickory Hill Saline, CA 48176 USA Email: shares@ndzh.com Qin Wu Huawei 101 Software Avenue, Yuhua District Nanjing, Jiangsu 210012 China Email: sunseawq@huawei.com Hares & Wu Expires August 17, 2014 [Page 16]