RTGWG Y. Qu Internet-Draft Futurewei Intended status: Standards Track J. Tantsura Expires: February 18, 2021 Apstra A. Lindem Cisco X. Liu Volta Networks August 17, 2020 A YANG Data Model for Routing Policy Management draft-ietf-rtgwg-policy-model-20 Abstract This document defines a YANG data model for configuring and managing routing policies in a vendor-neutral way and based on actual operational practice. The model provides a generic policy framework which can be augmented with protocol-specific policy configuration. 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 https://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 February 18, 2021. Copyright Notice Copyright (c) 2020 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 (https://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 Qu, et al. Expires February 18, 2021 [Page 1] Internet-Draft Routing Policy Model August 2020 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. Goals and approach . . . . . . . . . . . . . . . . . . . 3 2. Terminology and Notation . . . . . . . . . . . . . . . . . . 3 2.1. Tree Diagrams . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Prefixes in Data Node Names . . . . . . . . . . . . . . . 4 3. Model overview . . . . . . . . . . . . . . . . . . . . . . . 5 4. Route policy expression . . . . . . . . . . . . . . . . . . . 5 4.1. Defined sets for policy matching . . . . . . . . . . . . 6 4.2. Policy conditions . . . . . . . . . . . . . . . . . . . . 7 4.3. Policy actions . . . . . . . . . . . . . . . . . . . . . 8 4.4. Policy subroutines . . . . . . . . . . . . . . . . . . . 9 5. Policy evaluation . . . . . . . . . . . . . . . . . . . . . . 10 6. Applying routing policy . . . . . . . . . . . . . . . . . . . 10 7. Routing protocol-specific policies . . . . . . . . . . . . . 11 8. Security Considerations . . . . . . . . . . . . . . . . . . . 13 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 10. YANG module . . . . . . . . . . . . . . . . . . . . . . . . . 15 10.1. Routing policy model . . . . . . . . . . . . . . . . . . 15 11. Policy examples . . . . . . . . . . . . . . . . . . . . . . . 36 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 38 12.1. Normative references . . . . . . . . . . . . . . . . . . 38 12.2. Informative references . . . . . . . . . . . . . . . . . 40 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 40 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 41 1. Introduction This document describes a YANG [RFC7950] data model for routing policy configuration based on operational usage and best practices in a variety of service provider networks. The model is intended to be vendor-neutral, in order to allow operators to manage policy configuration in a consistent, intuitive way in heterogeneous environments with routers supplied by multiple vendors. The YANG modules in this document conform to the Network Management Datastore Architecture (NMDA) [RFC8342]. Qu, et al. Expires February 18, 2021 [Page 2] Internet-Draft Routing Policy Model August 2020 1.1. Goals and approach This model does not aim to be feature complete -- it is a subset of the policy configuration parameters available in a variety of vendor implementations, but supports widely used constructs for managing how routes are imported, exported, and modified across different routing protocols. The model development approach has been to examine actual policy configurations in use across a number of operator networks. Hence the focus is on enabling policy configuration capabilities and structure that are in wide use. Despite the differences in details of policy expressions and conventions in various vendor implementations, the model reflects the observation that a relatively simple condition-action approach can be readily mapped to several existing vendor implementations, and also gives operators an intuitive and straightforward way to express policy without sacrificing flexibility. A side effect of this design decision is that legacy methods for expressing policies are not considered. Such methods could be added as an augmentation to the model if needed. Consistent with the goal to produce a data model that is vendor neutral, only policy expressions that are deemed to be widely available in existing major implementations are included in the model. Those configuration items that are only available from a single implementation are omitted from the model with the expectation they will be available in separate vendor-provided modules that augment the current model. 2. Terminology and Notation The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. Routing Policy: A routing policy defines how routes are imported, exported, modified, and advertised between routing protocol instances or within a single routing protocol instance. The following terms are defined in [RFC8342]: o client o server o configuration Qu, et al. Expires February 18, 2021 [Page 3] Internet-Draft Routing Policy Model August 2020 o system state o operational state o intended configuration The following terms are defined in [RFC7950]: o action o augment o container o container with presence o data model o data node o feature o leaf o list o mandatory node o module o schema tree o RPC (Remote Procedure Call) operation 2.1. Tree Diagrams Tree diagrams used in this document follow the notation defined in [RFC8340]. 2.2. Prefixes in Data Node Names In this document, names of data nodes, actions, and other data model objects are often used without a prefix, as long as it is clear from the context in which YANG module each name is defined. Otherwise, names are prefixed using the standard prefix associated with the corresponding YANG module, as shown in Table 1. Qu, et al. Expires February 18, 2021 [Page 4] Internet-Draft Routing Policy Model August 2020 +---------+--------------------------------+----------------------+ | Prefix | YANG module | Reference | +---------+--------------------------------+----------------------+ | if | ietf-interfaces | [RFC8343] | | | | | | rt | ietf-routing | [RFC8349] | | | | | | yang | ietf-yang-types | [RFC6991] | | | | | | inet | ietf-inet-types | [RFC6991] | | | | | | if-ext | ietf-if-extensions | [INTF-EXT-YANG] | | | | | | if-flex | ietf-if-flexible-encapsulation | [SUB-INTF-VLAN-YANG] | +---------+--------------------------------+----------------------+ Table 1: Prefixes and Corresponding YANG Modules 3. Model overview The routing policy module has three main parts: o A generic framework to express policies as sets of related conditions and actions. This includes match sets and actions that are useful across many routing protocols. o A structure that allows routing protocol models to add protocol- specific policy conditions and actions though YANG augmentations. There is a complete example of this for BGP [RFC4271] policies in the proposed vendor-neutral BGP data model [I-D.ietf-idr-bgp-model]. o A reusable grouping for attaching import and export rules in the context of routing configuration for different protocols, VRFs, etc. This also enables creation of policy chains and expressing default policy behavior. The module makes use of the standard Internet types, such as IP addresses, autonomous system numbers, etc., defined in RFC 6991 [RFC6991]. 4. Route policy expression Policies are expressed as a sequence of top-level policy definitions each of which consists of a sequence of policy statements. Policy statements in turn consist of simple condition-action tuples. Conditions may include multiple match or comparison operations, and similarly, actions may effect multiple changes to route attributes, Qu, et al. Expires February 18, 2021 [Page 5] Internet-Draft Routing Policy Model August 2020 or indicate a final disposition of accepting or rejecting the route. This structure is shown below. +--rw routing-policy +--rw policy-definitions +--rw policy-definition* [name] +--rw name string +--rw statements +--rw statement* [name] +--rw name string +--rw conditions | ... +--rw actions ... 4.1. Defined sets for policy matching The models provide a set of generic sets that can be used for matching in policy conditions. These sets are applicable for route selection across multiple routing protocols. They may be further augmented by protocol-specific models which have their own defined sets. The supported defined sets include: o prefix sets - define a set of IP prefixes, each with an associated IP prefix and netmask range (or exact length) o neighbor sets - define a set of neighboring nodes by their IP addresses. These sets are used for selecting routes based on the neighbors advertising the routes. o tag set - define a set of generic tag values that can be used in matches for filtering routes The model structure for defined sets is shown below. Qu, et al. Expires February 18, 2021 [Page 6] Internet-Draft Routing Policy Model August 2020 +--rw routing-policy +--rw defined-sets | +--rw prefix-sets | | +--rw prefix-set* [name] | | +--rw name string | | +--rw mode? enumeration | | +--rw prefixes | | +--rw prefix-list* [ip-prefix mask-length-lower | | mask-length-upper] | | +--rw ip-prefix inet:ip-prefix | | +--rw mask-length-lower uint8 | | +--rw mask-length-upper uint8 | +--rw neighbor-sets | | +--rw neighbor-set* [name] | | +--rw name string | | +--rw address* inet:ip-address | +--rw tag-sets | +--rw tag-set* [name] | +--rw name string | +--rw tag-value* tag-type 4.2. Policy conditions Policy statements consist of a set of conditions and actions (either of which may be empty). Conditions are used to match route attributes against a defined set (e.g., a prefix set), or to compare attributes against a specific value. Match conditions may be further modified using the match-set-options configuration which allows network operators to change the behavior of a match. Three options are supported: o ALL - match is true only if the given value matches all members of the set. o ANY - match is true if the given value matches any member of the set. o INVERT - match is true if the given value does not match any member of the given set. Not all options are appropriate for matching against all defined sets (e.g., match ALL in a prefix set does not make sense). In the model, a restricted set of match options is used where applicable. Qu, et al. Expires February 18, 2021 [Page 7] Internet-Draft Routing Policy Model August 2020 Comparison conditions may similarly use options to change how route attributes should be tested, e.g., for equality or inequality, against a given value. While most policy conditions will be added by individual routing protocol models via augmentation, this routing policy model includes several generic match conditions and also the ability to test which protocol or mechanism installed a route (e.g., BGP, IGP, static, etc.). The conditions included in the model are shown below. +--rw routing-policy +--rw policy-definitions +--rw policy-definition* [name] +--rw name string +--rw statements +--rw statement* [name] +--rw conditions | +--rw call-policy? | +--rw source-protocol? | +--rw match-interface | | +--rw interface? | | +--rw subinterface? | +--rw match-prefix-set | | +--rw prefix-set? | | +--rw match-set-options? | +--rw match-neighbor-set | | +--rw neighbor-set? | +--rw match-tag-set | | +--rw tag-set? | | +--rw match-set-options? | +--rw match-route-type* identityref 4.3. Policy actions When policy conditions are satisfied, policy actions are used to set various attributes of the route being processed, or to indicate the final disposition of the route, i.e., accept or reject. Similar to policy conditions, the routing policy model includes generic actions in addition to the basic route disposition actions. These are shown below. Qu, et al. Expires February 18, 2021 [Page 8] Internet-Draft Routing Policy Model August 2020 +--rw routing-policy +--rw policy-definitions +--rw policy-definition* [name] +--rw statements +--rw statement* [name] +--rw actions +--rw policy-result? policy-result-type +--rw set-metric | +--rw metric-modification? | | metric-modification-type | +--rw metric? uint32 +--rw set-metric-type | +--rw metric-type? identityref +--rw set-route-level | +--rw route-level? identityref +--rw set-preference? uint16 +--rw set-tag? tag-type +--rw set-application-tag? tag-type 4.4. Policy subroutines Policy 'subroutines' (or nested policies) are supported by allowing policy statement conditions to reference other policy definitions using the call-policy configuration. Called policies apply their conditions and actions before returning to the calling policy statement and resuming evaluation. The outcome of the called policy affects the evaluation of the calling policy. If the called policy results in an accept-route, then the subroutine returns an effective boolean true value to the calling policy. For the calling policy, this is equivalent to a condition statement evaluating to a true value and evaluation of the policy continues (see Section 5). Note that the called policy may also modify attributes of the route in its action statements. Similarly, a reject-route action returns false and the calling policy evaluation will be affected accordingly. When the end of the subroutine policy chain is reached, the default route disposition action is returned (i.e., boolean false for reject-route unless an alternate default action is specified for the chain). Consequently, a subroutine cannot explicitly accept or reject a route. Rather it merely provides an indication that 'call-policy' condition returns boolean true or false indicating whether or not the condition matches. Route acceptance or rejection is solely determined by the top-level policy. Note that the called policy may itself call other policies (subject to implementation limitations). The model does not prescribe a nesting depth because this varies among implementations. For example, some major implementation may only support a single level of subroutine recursion. As with any routing policy construction, care Qu, et al. Expires February 18, 2021 [Page 9] Internet-Draft Routing Policy Model August 2020 must be taken with nested policies to ensure that the effective return value results in the intended behavior. Nested policies are a convenience in many routing policy constructions but creating policies nested beyond a small number of levels (e.g., 2-3) are discouraged. Also, implementations should have validation to ensure that there is no recursion amongst nested routing policies. 5. Policy evaluation Evaluation of each policy definition proceeds by evaluating its corresponding individual policy statements in order. When all the condition statements in a policy statement are satisfied, the corresponding action statements are executed. If the actions include either accept-route or reject-route actions, evaluation of the current policy definition stops, and no further policy definitions in the chain are evaluated. If the conditions are not satisfied, then evaluation proceeds to the next policy statement. If none of the policy statement conditions are satisfied, then evaluation of the current policy definition stops, and the next policy definition in the chain is evaluated. When the end of the policy chain is reached, the default route disposition action is performed (i.e., reject-route unless an alternate default action is specified for the chain). Note that the route's pre-policy attributes are always used for testing policy statement conditions. In other words, if actions modify the policy application specific attributes, those modifications are not used for policy statement conditions. 6. Applying routing policy Routing policy is applied by defining and attaching policy chains in various routing contexts. Policy chains are sequences of policy definitions (described in Section 4). They can be referenced from different contexts. For example, a policy chain could be associated with a routing protocol and used to control its interaction with its protocol peers. Or, it could be used to control the interaction between a routing protocol and the local routing information base. A policy chain has an associated direction (import or export), with respect to the context in which it is referenced. The routing policy model defines an apply-policy grouping that can be imported and used by other models. As shown below, it allows definition of import and export policy chains, as well as specifying the default route disposition to be used when no policy definition in the chain results in a final decision. Qu, et al. Expires February 18, 2021 [Page 10] Internet-Draft Routing Policy Model August 2020 +--rw apply-policy | +--rw import-policy* | +--rw default-import-policy? default-policy-type | +--rw export-policy* | +--rw default-export-policy? default-policy-type The default policy defined by the model is to reject the route for both import and export policies. 7. Routing protocol-specific policies Routing models that require the ability to apply routing policy may augment the routing policy model with protocol or other specific policy configuration. The routing policy model assumes that additional defined sets, conditions, and actions may all be added by other models. An example of this is shown below, in which the BGP configuration model in [I-D.ietf-idr-bgp-model] adds new defined sets to match on community values or AS paths. The model similarly augments BGP- specific conditions and actions in the corresponding sections of the routing policy model. module: ietf-routing-policy +--rw routing-policy +--rw defined-sets | +--rw prefix-sets | | +--rw prefix-set* [name] | | +--rw name string | | +--rw mode? enumeration | | +--rw prefixes | | +--rw prefix-list* [ip-prefix mask-length-lower | | mask-length-upper] | | +--rw ip-prefix inet:ip-prefix | | +--rw mask-length-lower uint8 | | +--rw mask-length-upper uint8 | +--rw neighbor-sets | | +--rw neighbor-set* [name] | | +--rw name string | | +--rw address* inet:ip-address | +--rw tag-sets | | +--rw tag-set* [name] | | +--rw name string | | +--rw tag-value* tag-type | +--rw bp:bgp-defined-sets | +--rw bp:community-sets | | +--rw bp:community-set* [name] | | +--rw bp:name string Qu, et al. Expires February 18, 2021 [Page 11] Internet-Draft Routing Policy Model August 2020 | | +--rw bp:member* union | +--rw bp:ext-community-sets | | +--rw bp:ext-community-set* [name] | | +--rw bp:name string | | +--rw bp:member* union | +--rw bp:as-path-sets | +--rw bp:as-path-set* [name] | +--rw bp:name string | +--rw bp:member* string +--rw policy-definitions +--rw policy-definition* [name] +--rw name string +--rw statements +--rw statement* [name] +--rw name string +--rw conditions | +--rw call-policy? | +--rw source-protocol? identityref | +--rw match-interface | | +--rw interface? | | +--rw subinterface? | +--rw match-prefix-set | | +--rw prefix-set? prefix-set/name | | +--rw match-set-options? match-set-options-type | +--rw match-neighbor-set | | +--rw neighbor-set? | +--rw match-tag-set | | +--rw tag-set? | | +--rw match-set-options? match-set-options-type | +--rw match-route-type* identityref | +--rw bp:bgp-conditions | +--rw bp:med-eq? uint32 | +--rw bp:origin-eq? bt:bgp-origin-attr-type | +--rw bp:next-hop-in* inet:ip-address-no-zone | +--rw bp:afi-safi-in* identityref | +--rw bp:local-pref-eq? uint32 | +--rw bp:route-type? enumeration | +--rw bp:community-count | +--rw bp:as-path-length | +--rw bp:match-community-set | | +--rw bp:community-set? | | +--rw bp:match-set-options? | +--rw bp:match-ext-community-set | | +--rw bp:ext-community-set? | | +--rw bp:match-set-options? | +--rw bp:match-as-path-set | +--rw bp:as-path-set? | +--rw bp:match-set-options? Qu, et al. Expires February 18, 2021 [Page 12] Internet-Draft Routing Policy Model August 2020 +--rw actions +--rw policy-result? policy-result-type +--rw set-metric | +--rw metric-modification? | +--rw metric? uint32 +--rw set-metric-type | +--rw metric-type? identityref +--rw set-route-level | +--rw route-level? identityref +--rw set-preference? uint16 +--rw set-tag? tag-type +--rw set-application-tag? tag-type +--rw bp:bgp-actions +--rw bp:set-route-origin?bt:bgp-origin-attr-type +--rw bp:set-local-pref? uint32 +--rw bp:set-next-hop? bgp-next-hop-type +--rw bp:set-med? bgp-set-med-type +--rw bp:set-as-path-prepend | +--rw bp:repeat-n? uint8 +--rw bp:set-community | +--rw bp:method? enumeration | +--rw bp:options? | +--rw bp:inline | | +--rw bp:communities* union | +--rw bp:reference | +--rw bp:community-set-ref? +--rw bp:set-ext-community +--rw bp:method? enumeration +--rw bp:options? +--rw bp:inline | +--rw bp:communities* union +--rw bp:reference +--rw bp:ext-community-set-ref? 8. Security Considerations The YANG modules specified in this document define a schema for data that is designed to be accessed via network management protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446]. The NETCONF Access Control Model (NACM) [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a pre- configured subset of all available NETCONF or RESTCONF protocol operations and content. Qu, et al. Expires February 18, 2021 [Page 13] Internet-Draft Routing Policy Model August 2020 There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) to these data nodes without proper protection can have a negative effect on network operations. These are the subtrees and data nodes and their sensitivity/vulnerability: /routing-policy /routing-policy/defined-sets/prefix-sets /routing-policy/defined-sets/neighbor-sets /routing-policy/defined-sets/tag-sets /routing-policy/policy-definitions Unauthorized access to any data node of these subtrees can disclose the operational state information of routing policies on this device. Routing policy configuration has a significant impact on network operations, and, as such, any related model carries potential security risks. Unauthorized access or invalid data could cause major disruption. 9. IANA Considerations This document registers a URI in the IETF XML registry [RFC3688]. Following the format in [RFC3688], the following registration is requested to be made: URI: urn:ietf:params:xml:ns:yang:ietf-routing-policy Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. This document registers a YANG module in the YANG Module Names registry [RFC6020]. name: ietf-routing-policy namespace: urn:ietf:params:xml:ns:yang:ietf-routing-policy prefix: rt-pol reference: RFC XXXX Qu, et al. Expires February 18, 2021 [Page 14] Internet-Draft Routing Policy Model August 2020 10. YANG module The routing policy model is described by the YANG modules in the sections below. [RFC2328], [RFC3101], [RFC5130], and [RFC5302] are referenced here since they are referenced in the YANG model but not elsewhere in this document. 10.1. Routing policy model file "ietf-routing-policy@2020-08-17.yang" module ietf-routing-policy { yang-version "1.1"; namespace "urn:ietf:params:xml:ns:yang:ietf-routing-policy"; prefix rt-pol; import ietf-inet-types { prefix "inet"; reference "RFC 6991: Common YANG Data Types"; } import ietf-yang-types { prefix "yang"; reference "RFC 6991: Common YANG Data Types"; } import ietf-interfaces { prefix "if"; reference "RFC 8343: A YANG Data Model for Interface Management (NMDA Version)"; } import ietf-routing { prefix "rt"; reference "RFC 8349: A YANG Data Model for Routing Management (NMDA Version)"; } import ietf-if-extensions { prefix "if-ext"; reference "RFC YYYY: Common Interface Extension YANG Data Models. Please replace YYYY with published RFC number for draft-ietf-netmod-intf-ext-yang."; } import ietf-if-flexible-encapsulation { Qu, et al. Expires February 18, 2021 [Page 15] Internet-Draft Routing Policy Model August 2020 prefix "if-flex"; reference "RFC ZZZZ: Sub-interface VLAN YANG Data Models. Please replace ZZZZ with published RFC number for draft-ietf-netmod-sub-intf-vlan-model."; } organization "IETF RTGWG - Routing Area Working Group"; contact "WG Web: WG List: Editor: Yingzhen Qu Jeff Tantsura Acee Lindem Xufeng Liu "; description "This module describes a YANG model for routing policy configuration. It is a limited subset of all of the policy configuration parameters available in the variety of vendor implementations, but supports widely used constructs for managing how routes are imported, exported, modified and advertised across different routing protocol instances or within a single routing protocol instance. This module is intended to be used in conjunction with routing protocol configuration modules (e.g., BGP) defined in other models. Route policy expression: Policies are expressed as a set of top-level policy definitions, each of which consists of a sequence of policy statements. Policy statements consist of simple condition-action tuples. Conditions may include multiple match or comparison operations, and similarly actions may be a multitude of changes to route attributes or a final disposition of accepting or rejecting the route. Route policy evaluation: Policy definitions are referenced in routing protocol configurations using import and export configuration statements. The arguments are members of an ordered list of named policy definitions which comprise a policy chain, and Qu, et al. Expires February 18, 2021 [Page 16] Internet-Draft Routing Policy Model August 2020 optionally, an explicit default policy action (i.e., reject or accept). Evaluation of each policy definition proceeds by evaluating its corresponding individual policy statements in order. When a condition statement in a policy statement is satisfied, the corresponding action statement is executed. If the action statement has either accept-route or reject-route actions, policy evaluation of the current policy definition stops, and no further policy definitions in the chain are evaluated. If the condition is not satisfied, then evaluation proceeds to the next policy statement. If none of the policy statement conditions are satisfied, then evaluation of the current policy definition stops, and the next policy definition in the chain is evaluated. When the end of the policy chain is reached, the default route disposition action is performed (i.e., reject-route unless an alternate default action is specified for the chain). Policy 'subroutines' (or nested policies) are supported by allowing policy statement conditions to reference another policy definition which applies conditions and actions from the referenced policy before returning to the calling policy statement and resuming evaluation. If the called policy results in an accept-route (either explicit or by default), then the subroutine returns an effective true value to the calling policy. Similarly, a reject-route action returns false. If the subroutine returns true, the calling policy continues to evaluate the remaining conditions with the initial data if route attribute values are modified. Copyright (c) 2020 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Simplified BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices. The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL Qu, et al. Expires February 18, 2021 [Page 17] Internet-Draft Routing Policy Model August 2020 NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this document are to be interpreted as described in BCP 14 (RFC 2119) (RFC 8174) when, and only when, they appear in all capitals, as shown here. This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision "2020-08-17" { description "Initial revision."; reference "RFC XXXX: Routing Policy Configuration Model for Service Provider Networks"; } /* Identities */ identity metric-type { description "Base identity for route metric types."; } identity ospf-type-1-metric { base metric-type; description "Identity for the OSPF type 1 external metric types. It is only applicable to OSPF routes."; reference "RFC 2328 - OSPF Version 2"; } identity ospf-type-2-metric { base metric-type; description "Identity for the OSPF type 2 external metric types. It is only applicable to OSPF routes."; reference "RFC 2328 - OSPF Version 2"; } identity isis-internal-metric { base metric-type; description "Identity for the IS-IS internal metric types. It is only applicable to IS-IS routes."; reference Qu, et al. Expires February 18, 2021 [Page 18] Internet-Draft Routing Policy Model August 2020 "RFC 5302 - Domain-Wide Prefix Distribution with Two-Level IS-IS"; } identity isis-external-metric { base metric-type; description "Identity for the IS-IS external metric types. It is only applicable to IS-IS routes."; reference "RFC 5302 - Domain-Wide Prefix Distribution with Two-Level IS-IS"; } identity route-level { description "Base identity for route import or export level."; } identity ospf-normal { base route-level; description "Identity for OSPF importation into normal areas It is only applicable to routes imported into the OSPF protocol."; reference "RFC 2328 - OSPF Version 2"; } identity ospf-nssa-only { base route-level; description "Identity for the OSPF Not-So-Stubby Area (NSSA) area importation. It is only applicable to routes imported into the OSPF protocol."; reference "RFC 3101: The OSPF Not-So-Stubby Area (NSSA) Option"; } identity ospf-normal-nssa { base route-level; description "Identity for OSPF importation into both normal and NSSA areas, it is only applicable to routes imported into the OSPF protocol."; reference "RFC 3101: The OSPF Not-So-Stubby Area (NSSA) Option"; } Qu, et al. Expires February 18, 2021 [Page 19] Internet-Draft Routing Policy Model August 2020 identity isis-level-1 { base route-level; description "Identity for IS-IS Level 1 area importation. It is only applicable to routes imported into the IS-IS protocol."; reference "RFC 5302 - Domain-Wide Prefix Distribution with Two-Level IS-IS"; } identity isis-level-2 { base route-level; description "Identity for IS-IS Level 2 area importation. It is only applicable to routes imported into the IS-IS protocol."; reference "RFC 5302 - Domain-Wide Prefix Distribution with Two-Level IS-IS"; } identity isis-level-1-2 { base route-level; description "Identity for IS-IS Level 1 and Level 2 area importation. It is only applicable to routes imported into the IS-IS protocol."; reference "RFC 5302 - Domain-Wide Prefix Distribution with Two-Level IS-IS"; } identity proto-route-type { description "Base identity for route type within a protocol."; } identity isis-level-1-type { base proto-route-type; description "Identity for IS-IS Level 1 route type. It is only applicable to IS-IS routes."; reference "RFC 5302 - Domain-Wide Prefix Distribution with Two-Level IS-IS"; } identity isis-level-2-type { base proto-route-type; Qu, et al. Expires February 18, 2021 [Page 20] Internet-Draft Routing Policy Model August 2020 description "Identity for IS-IS Level 2 route type. It is only applicable to IS-IS routes."; reference "RFC 5302 - Domain-Wide Prefix Distribution with Two-Level IS-IS"; } identity ospf-internal-type { base proto-route-type; description "Identity for OSPF intra-area or inter-area route type. It is only applicable to OSPF routes."; reference "RFC 2328 - OSPF Version 2"; } identity ospf-external-type { base proto-route-type; description "Identity for OSPF external type 1/2 route type. It is only applicable to OSPF routes."; reference "RFC 2328 - OSPF Version 2"; } identity ospf-external-t1-type { base ospf-external-type; description "Identity for OSPF external type 1 route type. It is only applicable to OSPF routes."; reference "RFC 2328 - OSPF Version 2"; } identity ospf-external-t2-type { base ospf-external-type; description "Identity for OSPF external type 2 route type. It is only applicable to OSPF routes."; reference "RFC 2328 - OSPF Version 2"; } identity ospf-nssa-type { base proto-route-type; description "Identity for OSPF NSSA type 1/2 route type. Qu, et al. Expires February 18, 2021 [Page 21] Internet-Draft Routing Policy Model August 2020 It is only applicable to OSPF routes."; reference "RFC 3101: The OSPF Not-So-Stubby Area (NSSA) Option"; } identity ospf-nssa-t1-type { base ospf-nssa-type; description "Identity for OSPF NSSA type 1 route type. It is only applicable to OSPF routes."; reference "RFC 3101: The OSPF Not-So-Stubby Area (NSSA) Option"; } identity ospf-nssa-t2-type { base ospf-nssa-type; description "Identity for OSPF NSSA type 2 route type. It is only applicable to OSPF routes."; reference "RFC 3101: The OSPF Not-So-Stubby Area (NSSA) Option"; } identity bgp-internal { base proto-route-type; description "Identity for routes learned from internal BGP (iBGP). It is only applicable to BGP routes."; reference "RFC 4271: A Border Gateway Protocol 4 (BGP-4)"; } identity bgp-external { base proto-route-type; description "Identity for routes learned from external BGP (eBGP). It is only applicable to BGP routes."; reference "RFC 4271: A Border Gateway Protocol 4 (BGP-4)"; } /* Type Definitions */ typedef default-policy-type { type enumeration { enum accept-route { description "Default policy to accept the route."; Qu, et al. Expires February 18, 2021 [Page 22] Internet-Draft Routing Policy Model August 2020 } enum reject-route { description "Default policy to reject the route."; } } description "Type used to specify route disposition in a policy chain. This typedef retained for name compatibility with default import and export policy."; } typedef policy-result-type { type enumeration { enum accept-route { description "Policy accepts the route."; } enum reject-route { description "Policy rejects the route."; } } description "Type used to specify route disposition in a policy chain."; } typedef tag-type { type union { type uint32; type yang:hex-string; } description "Type for expressing route tags on a local system, including IS-IS and OSPF; may be expressed as either decimal or hexadecimal integer."; reference "RFC 2328 - OSPF Version 2 RFC 5130 - A Policy Control Mechanism in IS-IS Using Administrative Tags"; } typedef match-set-options-type { type enumeration { enum any { description Qu, et al. Expires February 18, 2021 [Page 23] Internet-Draft Routing Policy Model August 2020 "Match is true if given value matches any member of the defined set."; } enum all { description "Match is true if given value matches all members of the defined set."; } enum invert { description "Match is true if given value does not match any member of the defined set."; } } default any; description "Options that govern the behavior of a match statement. The default behavior is any, i.e., the given value matches any of the members of the defined set."; } typedef metric-modification-type { type enumeration { enum set-metric { description "Set the metric to the specified value."; } enum add-metric { description "Add the specified value to the existing metric. If the result would overflow the maximum metric (0xffffffff), set the metric to the maximum."; } enum subtract-metric { description "Subtract the specified value to the existing metric. If the result would be less than 0, set the metric to 0."; } } description "Type used to specify how to set the metric given the specified value."; } /* Groupings */ grouping prefix { description Qu, et al. Expires February 18, 2021 [Page 24] Internet-Draft Routing Policy Model August 2020 "Configuration data for a prefix definition."; leaf ip-prefix { type inet:ip-prefix; mandatory true; description "The IP prefix represented as an IPv6 or IPv4 network number followed by a prefix length with an intervening slash character as a delimiter. All members of the prefix set should be of the same address family as the prefix-set mode."; } leaf mask-length-lower { type uint8; description "Mask length range lower bound. It should not be less than the prefix length defined in ip-prefix."; } leaf mask-length-upper { type uint8 { range "1..128"; } must "../mask-length-upper >= ../mask-length-lower" { error-message "The upper bound should not be less" + "than lower bound."; } description "Mask length range upper bound. The combination of mask-length-lower and mask-length-upper define a range for the mask length, or single 'exact' length if mask-length-lower and mask-length-upper are equal. Example: 192.0.2.0/24 through 192.0.2.0/26 would be expressed as prefix: 192.0.2.0/24, mask-length-lower=24, mask-length-upper=26 Example: 192.0.2.0/24 (an exact match) would be expressed as prefix: 192.0.2.0/24, mask-length-lower=24, mask-length-upper=24"; } } grouping match-set-options-group { Qu, et al. Expires February 18, 2021 [Page 25] Internet-Draft Routing Policy Model August 2020 description "Grouping containing options relating to how a particular set should be matched."; leaf match-set-options { type match-set-options-type; description "Optional parameter that governs the behavior of the match operation."; } } grouping match-set-options-restricted-group { description "Grouping for a restricted set of match operation modifiers."; leaf match-set-options { type match-set-options-type { enum any { description "Match is true if given value matches any member of the defined set."; } enum invert { description "Match is true if given value does not match any member of the defined set."; } } description "Optional parameter that governs the behavior of the match operation. This leaf only supports matching on 'any' member of the set or 'invert' the match. Matching on 'all' is not supported."; } } grouping match-interface-condition { description "This grouping provides interface match condition."; container match-interface { leaf interface { type leafref { path "/if:interfaces/if:interface/if:name"; } description Qu, et al. Expires February 18, 2021 [Page 26] Internet-Draft Routing Policy Model August 2020 "Reference to a base interface. If a reference to a subinterface is required, this leaf must be specified to indicate the base interface."; } leaf subinterface { type leafref { path "/if:interfaces/if:interface/if-ext:encapsulation" + "/if-flex:flexible/if-flex:match" + "/if-flex:dot1q-vlan-tagged" + "/if-flex:outer-tag/if-flex:vlan-id"; } description "Reference to a subinterface -- this requires the base interface to be specified using the interface leaf in this container. If only a reference to a base interface is required, this leaf should not be set."; } description "Container for interface match conditions"; } } grouping match-route-type-condition { description "This grouping provides route-type match condition"; leaf-list match-route-type { type identityref { base proto-route-type; } description "Condition to check the protocol-specific type of route. This is normally used during route importation to select routes or to set protocol specific attributes based on the route type."; } } grouping prefix-set-condition { description "This grouping provides prefix-set conditions."; container match-prefix-set { leaf prefix-set { type leafref { path "../../../../../../../defined-sets/" + "prefix-sets/prefix-set/name"; Qu, et al. Expires February 18, 2021 [Page 27] Internet-Draft Routing Policy Model August 2020 } description "References a defined prefix set."; } uses match-set-options-restricted-group; description "Match a referenced prefix-set according to the logic defined in the match-set-options leaf."; } } grouping neighbor-set-condition { description "This grouping provides neighbor-set conditions."; container match-neighbor-set { leaf neighbor-set { type leafref { path "../../../../../../../defined-sets/neighbor-sets/" + "neighbor-set/name"; require-instance true; } description "References a defined neighbor set."; } description "Match a referenced neighbor set according to the logic defined in the match-set-options-leaf."; } } grouping tag-set-condition { description "This grouping provides tag-set conditions."; container match-tag-set { leaf tag-set { type leafref { path "../../../../../../../defined-sets/tag-sets" + "/tag-set/name"; require-instance true; } description "References a defined tag set."; } uses match-set-options-restricted-group; Qu, et al. Expires February 18, 2021 [Page 28] Internet-Draft Routing Policy Model August 2020 description "Match a referenced tag set according to the logic defined in the match-options-set leaf."; } } grouping apply-policy-import { description "Grouping for applying import policies."; leaf-list import-policy { type leafref { path "/rt-pol:routing-policy/rt-pol:policy-definitions/" + "rt-pol:policy-definition/rt-pol:name"; require-instance true; } ordered-by user; description "List of policy names in sequence to be applied on receiving redistributed routes from another routing protocol or receiving a routing update in the current context, e.g., for the current peer group, neighbor, address family, etc."; } leaf default-import-policy { type default-policy-type; default reject-route; description "Explicitly set a default policy if no policy definition in the import policy chain is satisfied."; } } grouping apply-policy-export { description "Grouping for applying export policies."; leaf-list export-policy { type leafref { path "/rt-pol:routing-policy/rt-pol:policy-definitions/" + "rt-pol:policy-definition/rt-pol:name"; require-instance true; } ordered-by user; description "List of policy names in sequence to be applied on Qu, et al. Expires February 18, 2021 [Page 29] Internet-Draft Routing Policy Model August 2020 redistributing routes from one routing protocol to another or sending a routing update in the current context, e.g., for the current peer group, neighbor, address family, etc."; } leaf default-export-policy { type default-policy-type; default reject-route; description "Explicitly set a default policy if no policy definition in the export policy chain is satisfied."; } } grouping apply-policy-group { description "Top level container for routing policy applications. This grouping is intended to be used in routing models where needed."; container apply-policy { description "Anchor point for routing policies in the model. Import and export policies are with respect to the local routing table, i.e., export (send) and import (receive), depending on the context."; uses apply-policy-import; uses apply-policy-export; } } container routing-policy { description "Top-level container for all routing policy."; container defined-sets { description "Predefined sets of attributes used in policy match statements."; container prefix-sets { description "Data definitions for a list of IPv4 or IPv6 prefixes which are matched as part of a policy."; list prefix-set { Qu, et al. Expires February 18, 2021 [Page 30] Internet-Draft Routing Policy Model August 2020 key "name mode"; description "List of the defined prefix sets"; leaf name { type string; description "Name of the prefix set -- this is used as a label to reference the set in match conditions."; } leaf mode { type enumeration { enum ipv4 { description "Prefix set contains IPv4 prefixes only."; } enum ipv6 { description "Prefix set contains IPv6 prefixes only."; } } description "Indicates the mode of the prefix set, in terms of which address families (IPv4, IPv6, or both) are present. The mode provides a hint, but the device must validate that all prefixes are of the indicated type, and is expected to reject the configuration if there is a discrepancy."; } container prefixes { description "Container for the list of prefixes in a policy prefix list. Since individual prefixes do not have unique actions, the order in which the prefix in prefix-list are matched has no impact on the outcome outcome and is is left to the implementation. A given prefix-set condition is statisfied if the input prefix matches any of the prefixes in the prefix-set."; list prefix-list { key "ip-prefix mask-length-lower mask-length-upper"; description "List of prefixes in the prefix set."; uses prefix; Qu, et al. Expires February 18, 2021 [Page 31] Internet-Draft Routing Policy Model August 2020 } } } } container neighbor-sets { description "Data definition for a list of IPv4 or IPv6 neighbors which can be matched in a routing policy."; list neighbor-set { key "name"; description "List of defined neighbor sets for use in policies."; leaf name { type string; description "Name of the neighbor set -- this is used as a label to reference the set in match conditions."; } leaf-list address { type inet:ip-address; description "List of IP addresses in the neighbor set."; } } } container tag-sets { description "Data definitions for a list of tags which can be matched in policies."; list tag-set { key "name"; description "List of tag set definitions."; leaf name { type string; description "Name of the tag set -- this is used as a label to reference the set in match conditions."; } leaf-list tag-value { Qu, et al. Expires February 18, 2021 [Page 32] Internet-Draft Routing Policy Model August 2020 type tag-type; description "Value of the tag set member."; } } } } container policy-definitions { description "Enclosing container for the list of top-level policy definitions."; list policy-definition { key "name"; description "List of top-level policy definitions, keyed by unique name. These policy definitions are expected to be referenced (by name) in policy chains specified in import or export configuration statements."; leaf name { type string; description "Name of the top-level policy definition -- this name is used in references to the current policy."; } container statements { description "Enclosing container for policy statements."; list statement { key "name"; ordered-by user; description "Policy statements group conditions and actions within a policy definition. They are evaluated in the order specified (see the description of policy evaluation at the top of this module."; leaf name { type string; description "Name of the policy statement."; } container conditions { Qu, et al. Expires February 18, 2021 [Page 33] Internet-Draft Routing Policy Model August 2020 description "Condition statements for the current policy statement."; leaf call-policy { type leafref { path "../../../../../../" + "rt-pol:policy-definitions/" + "rt-pol:policy-definition/rt-pol:name"; require-instance true; } description "Applies the statements from the specified policy definition and then returns control the current policy statement. Note that the called policy may itself call other policies (subject to implementation limitations). This is intended to provide a policy 'subroutine' capability. The called policy should contain an explicit or a default route disposition that returns an effective true (accept-route) or false (reject-route), otherwise the behavior may be ambiguous."; } leaf source-protocol { type identityref { base rt:control-plane-protocol; } description "Condition to check the protocol / method used to install the route into the local routing table."; } uses match-interface-condition; uses prefix-set-condition; uses neighbor-set-condition; uses tag-set-condition; uses match-route-type-condition; } container actions { description "Top-level container for policy action statements."; leaf policy-result { type policy-result-type; description Qu, et al. Expires February 18, 2021 [Page 34] Internet-Draft Routing Policy Model August 2020 "Select the final disposition for the route, either accept or reject."; } container set-metric { leaf metric-modification { type metric-modification-type; description "Indicates how to modify the metric."; } leaf metric { type uint32; description "Metric value to set, add, or subtract."; } description "Set the metric for the route."; } container set-metric-type { leaf metric-type { type identityref { base metric-type; } description "Route metric type."; } description "Set the metric type for the route."; } container set-route-level { leaf route-level { type identityref { base route-level; } description "Route import or export level."; } description "Set the level for importation or exportation of routes."; } leaf set-preference { type uint16; description "Set the preference for the route."; } leaf set-tag { type tag-type; description Qu, et al. Expires February 18, 2021 [Page 35] Internet-Draft Routing Policy Model August 2020 "Set the tag for the route."; } leaf set-application-tag { type tag-type; description "Set the application tag for the route."; } } } } } } } } CODE ENDS> 11. Policy examples Below we show an example of XML-encoded configuration data using the routing policy and BGP models to illustrate both how policies are defined, and also how they can be applied. Note that the XML has been simplified for readability. prefix-set-A ipv4 192.0.2.0/24 24 32 198.51.100.0/24 24 32 Qu, et al. Expires February 18, 2021 [Page 36] Internet-Draft Routing Policy Model August 2020 cust-tag1 10 export-tagged-BGP term-0 cust-tag1 accept-route In the following example, all routes in the RIB that have been learned from OSPF advertisements corresponding to OSPF intra-area and inter-area route types should get advertised into ISIS level-2 advertisements. Qu, et al. Expires February 18, 2021 [Page 37] Internet-Draft Routing Policy Model August 2020 export-all-OSPF-prefixes-into-ISIS-level-2 term-0 ospf-internal-type isis-level-2 accept-route 12. References 12.1. Normative references [INTF-EXT-YANG] Wilton, R., Ball, D., tapsingh@cisco.com, t., and S. Sivaraj,, "Common Interface Extension YANG Data Models", 2019, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, DOI 10.17487/RFC2328, April 1998, . [RFC3101] Murphy, P., "The OSPF Not-So-Stubby Area (NSSA) Option", RFC 3101, DOI 10.17487/RFC3101, January 2003, . Qu, et al. Expires February 18, 2021 [Page 38] Internet-Draft Routing Policy Model August 2020 [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, DOI 10.17487/RFC4271, January 2006, . [RFC5130] Previdi, S., Shand, M., Ed., and C. Martin, "A Policy Control Mechanism in IS-IS Using Administrative Tags", RFC 5130, DOI 10.17487/RFC5130, February 2008, . [RFC5302] Li, T., Smit, H., and T. Przygienda, "Domain-Wide Prefix Distribution with Two-Level IS-IS", RFC 5302, DOI 10.17487/RFC5302, October 2008, . [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, . [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, . [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, . [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, . [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . Qu, et al. Expires February 18, 2021 [Page 39] Internet-Draft Routing Policy Model August 2020 [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, . [RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, . [RFC8343] Bjorklund, M., "A YANG Data Model for Interface Management", RFC 8343, DOI 10.17487/RFC8343, March 2018, . [RFC8349] Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for Routing Management (NMDA Version)", RFC 8349, DOI 10.17487/RFC8349, March 2018, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . [SUB-INTF-VLAN-YANG] Wilton, R., Ball, D., tapsingh@cisco.com, t., and S. Sivaraj, "Sub-interface VLAN YANG Data Model", 2019, . 12.2. Informative references [I-D.ietf-idr-bgp-model] Jethanandani, M., Patel, K., Hares, S., and J. Haas, "BGP YANG Model for Service Provider Networks", draft-ietf-idr- bgp-model-09 (work in progress), June 2020. Appendix A. Acknowledgements The routing policy module defined in this document is based on the OpenConfig route policy model. The authors would like to thank to OpenConfig for their contributions, especially Anees Shaikh, Rob Shakir, Kevin D'Souza, and Chris Chase. Qu, et al. Expires February 18, 2021 [Page 40] Internet-Draft Routing Policy Model August 2020 The authors are grateful for valuable contributions to this document and the associated models from: Ebben Aires, Luyuan Fang, Josh George, Stephane Litkowski, Ina Minei, Carl Moberg, Eric Osborne, Steve Padgett, Juergen Schoenwaelder, Jim Uttaro, Russ White, and John Heasley. Thanks to Mahesh Jethanandani, John Scudder, Chris Bower and Tom Petch for their reviews and comments. Authors' Addresses Yingzhen Qu Futurewei 2330 Central Expressway Santa Clara CA 95050 USA Email: yingzhen.qu@futurewei.com Jeff Tantsura Apstra Email: jefftant.ietf@gmail.com Acee Lindem Cisco 301 Midenhall Way Cary, NC 27513 US Email: acee@cisco.com Xufeng Liu Volta Networks Email: xufeng.liu.ietf@gmail.com Qu, et al. Expires February 18, 2021 [Page 41]