Spring Working Group K. Majumdar Internet-Draft K. Raza Intended status: Standards Track Cisco Expires: January 8, 2020 B. Decraene Orange July 07, 2019 YANG data model for BGP Segment Routing Extensions draft-majumdar-spring-bgp-sr-yang-00 Abstract This document defines a YANG data model that can be used to configure and manage Segment Routing extensions in BGP. 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 January 8, 2020. Copyright Notice Copyright (c) 2019 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 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. Majumdar, et al. Expires January 8, 2020 [Page 1] Internet-Draft Yang Model for BGP Segment Routing July 2019 This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2. BGP Segment Routing Yang model . . . . . . . . . . . . . . . 3 2.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2. SR Prefix SID (SR MPLS) . . . . . . . . . . . . . . . . . 4 2.3. Egress Peer Engineering . . . . . . . . . . . . . . . . . 4 3. Yang Tree . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. SR Prefix Sid (SR MPLS) . . . . . . . . . . . . . . . . . 4 3.2. Egress Peer Engineering . . . . . . . . . . . . . . . . . 6 4. Yang Module . . . . . . . . . . . . . . . . . . . . . . . . . 8 5. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 16 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 7. Security Considerations . . . . . . . . . . . . . . . . . . . 16 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 9.1. Normative References . . . . . . . . . . . . . . . . . . 17 9.2. Informative References . . . . . . . . . . . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 1. Introduction YANG [RFC6020] is a data definition language that was introduced to define the contents of a conceptual data store that allows networked devices to be managed using NETCONF [RFC6241]. YANG is proving relevant beyond its initial confines, as bindings to other interfaces (e.g. ReST) [RFC8040] and encodings other than XML (e.g. JSON) [RFC7951] are being defined. Furthermore, YANG data models can be used as the basis of implementation for other interfaces, such as CLI and programmatic APIs. This document defines the YANG model for Segment Routing specific extensions in BGP. Majumdar, et al. Expires January 8, 2020 [Page 2] Internet-Draft Yang Model for BGP Segment Routing July 2019 1.1. Requirements Language 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. 2. BGP Segment Routing Yang model 2.1. Overview Segment Routing (SR), as defined in [RFC8402], leverages the source routing paradigm where a node steers a packet through an ordered list of instructions, called segments. SR, thus, allows enforcing a flow through any topological path and/or service chain while maintaining per-flow state only at the ingress nodes to the SR domain. When applied to ipv6 data-plane (i.e. SRv6), the ordered set of instructions are realized via SRv6 SIDs. The various functions and behaviors corresponding to network programming using SRv6 are specified in [I-D.ietf-spring-srv6-network-programming]. This document defines Yang model for the Segment Routing extensions applicable for BGP as following: o Prefix sid extensions in the context of SR MPLS, as described in [I-D.ietf-idr-bgp-prefix-sid]. o Egress Peer Engineering (EPE) as described in [I-D.ietf-spring- segment-routing-central-epe]. The Yang extensions proposed in this model augment the base BGP model defined in [I-D.ietf-idr-bgp-model]. Note: Base BGP model does not have a common structure for BGP RIB. The placeholder containers defined in this model can be removed once base BGP model has the BGP RIB structure. The modeling in this document complies with the Network Management Datastore Architecture (NMDA) [RFC8342]. The operational state data is combined with the associated configuration data in the same hierarchy [RFC8407]. When protocol states are retrieved from the NMDA operational state datastore, the returned states cover all "config true" (rw) and "config false" (ro) nodes defined in the schema. Majumdar, et al. Expires January 8, 2020 [Page 3] Internet-Draft Yang Model for BGP Segment Routing July 2019 2.2. SR Prefix SID (SR MPLS) Prefix SID attribute in BGP in the context of SR MPLS, carries the label index and SRGB block information. o The configuration to attach the label index is modeled as a new route-policy set action. BGP policy actions from the BGP policy module defined in base BGP yang model [I-D.ietf-idr-bgp-model] are augmented for this purpose. o The configuration related to SR Mapping Server in the context of BGP prefix SID, is TBD. o Prefix SID attribute received with the BGP route is modeled under BGP AF mode for select address families. This information is applicable per route. 2.3. Egress Peer Engineering Egress Peer Engineering (EPE) in the context of Segment Routing is described in [I-D.ietf-spring-segment-routing-central-epe]. EPE is enabled in the context of BGP neighbor session. Three different types of EPE SIDs namely, Peer node SID, Peer adjacency SID and Peer set SID correspond to the segments required for source routed inter domain paths. EPE SID(s) for each type above, can be statically configured or dynamically allocated by the node. Further, FRR backup policy and backup SID can be specified per EPE. The configuration and state for the EPE parameters is modeled by augmenting the neighbor container defined in the base BGP model [I-D.ietf-idr-bgp-model]. The configuration and the applied config state are applicable for neighbor-groups as well. 3. Yang Tree 3.1. SR Prefix Sid (SR MPLS) module: ietf-bgp-sr augment /rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:ipv4-unicast: +--ro routes +--ro route* [prefix neighbor add-path-id] +--ro prefix union +--ro neighbor inet:ip-address +--ro add-path-id uint32 augment /rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:ipv6-unicast: +--ro routes +--ro route* [prefix neighbor add-path-id] +--ro prefix union +--ro neighbor inet:ip-address Majumdar, et al. Expires January 8, 2020 [Page 4] Internet-Draft Yang Model for BGP Segment Routing July 2019 +--ro add-path-id uint32 augment /rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:ipv4-labeled-unicast: +--ro routes +--ro route* [prefix neighbor add-path-id] +--ro prefix union +--ro neighbor inet:ip-address +--ro add-path-id uint32 +--ro prefix-sid +--ro label-index? uint32 +--ro originator-srgb +--ro srgb-ranges* [srgb-min srgb-max] +--ro srgb-min rt-types:mpls-label +--ro srgb-max rt-types:mpls-label augment /rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:ipv6-labeled-unicast: +--ro routes +--ro route* [prefix neighbor add-path-id] +--ro prefix union +--ro neighbor inet:ip-address +--ro add-path-id uint32 +--ro prefix-sid +--ro label-index? uint32 +--ro originator-srgb +--ro srgb-ranges* [srgb-min srgb-max] +--ro srgb-min rt-types:mpls-label +--ro srgb-max rt-types:mpls-label augment /rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:l3vpn-ipv4-unicast: +--ro routes +--ro route* [rd prefix neighbor add-path-id] +--ro rd rt-types:route-distinguisher +--ro prefix union +--ro neighbor inet:ip-address +--ro add-path-id uint32 augment /rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:l3vpn-ipv6-unicast: +--ro routes +--ro route* [rd prefix neighbor add-path-id] +--ro rd rt-types:route-distinguisher +--ro prefix union +--ro neighbor inet:ip-address +--ro add-path-id uint32 augment /rpol:routing-policy/rpol:policy-definitions/rpol:policy-definition/rpol:statements/rpol:statement/rpol:actions/rpol:policy-result: +--rw set-label-index? uint32 ... Majumdar, et al. Expires January 8, 2020 [Page 5] Internet-Draft Yang Model for BGP Segment Routing July 2019 3.2. Egress Peer Engineering Egress Peer Engineering Yang Tree applicable to neighbor and peer- group containers Majumdar, et al. Expires January 8, 2020 [Page 6] Internet-Draft Yang Model for BGP Segment Routing July 2019 module: ietf-bgp-sr augment /rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/bgp:bgp/bgp:neighbors/bgp:neighbor: +--rw egress-peer-engineering +--rw sid-allocation-type? enumeration +--rw explicit-sid? sid-type +--ro allocated-sid? sid-type +--rw peer-set-name? string +--rw backup | +--ro active? boolean | +--rw backup-type? enumeration | +--rw backup-peer? inet:ip-address | +--rw backup-sid? sid-type +--rw peer-adjacency* [first-hop-ipaddress] +--rw first-hop-ipaddress inet:ip-address +--ro first-hop-interface? string +--rw sid-allocation-type? enumeration +--rw explicit-sid? sid-type +--ro allocated-sid? sid-type +--rw backup +--ro active? boolean +--rw backup-type? enumeration +--rw backup-peer? inet:ip-address +--rw backup-sid? sid-type augment /rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/bgp:bgp/bgp:peer-groups/bgp:peer-group: +--rw egress-peer-engineering +--rw sid-allocation-type? enumeration +--rw explicit-sid? sid-type +--ro allocated-sid? sid-type +--rw peer-set-name? string +--rw backup | +--ro active? boolean | +--rw backup-type? enumeration | +--rw backup-peer? inet:ip-address | +--rw backup-sid? sid-type +--rw peer-adjacency* [first-hop-ipaddress] +--rw first-hop-ipaddress inet:ip-address +--ro first-hop-interface? string +--rw sid-allocation-type? enumeration +--rw explicit-sid? sid-type +--ro allocated-sid? sid-type +--rw backup +--ro active? boolean +--rw backup-type? enumeration +--rw backup-peer? inet:ip-address +--rw backup-sid? sid-type ... Majumdar, et al. Expires January 8, 2020 [Page 7] Internet-Draft Yang Model for BGP Segment Routing July 2019 4. Yang Module file "ietf-bgp-sr@2019-07-07.yang" module ietf-bgp-sr { namespace "urn:ietf:params:xml:ns:yang:ietf-bgp-sr"; prefix ietf-bgp-sr ; import ietf-routing-types { prefix rt-types; } import ietf-routing { prefix "rt"; } import ietf-inet-types { prefix inet; } import ietf-routing-policy { prefix rpol; } import ietf-bgp { prefix bgp; } import ietf-srv6-types { prefix srv6-types; } organization "IETF Spring Working Group"; contact "Spring working group - spring@ietf.org"; description "This YANG module defines a data model to configure and manage segment routing extensions in BGP. Terms and Acronyms AF : Address Family Majumdar, et al. Expires January 8, 2020 [Page 8] Internet-Draft Yang Model for BGP Segment Routing July 2019 BGP (bgp) : Border Gateway Protocol EPE : Egress Peer Engineering SR : Segment Routing SID : Segment Identifier VPN : Virtual Private Network VRF : Virtual Routing and Forwarding "; revision 2018-06-26 { description "Initial revision" ; reference ""; } // // New identities and typedefs for SR extensions // // Sid type union typedef sid-type { type union { type rt-types:mpls-label; type srv6-types:srv6-sid; } description "Type definition for Segment Identifier. This is a union type which can be either a SR MPLS SID in the form of a label, or a SRv6 SID in the form of an IPv6 address."; reference "TBD"; } // // SR Prefix SID related groupings // // Prefix SID attribute state in a route grouping sr-route-prefix-sid { description "SR Prefix SID attribute associated with BGP Route"; container prefix-sid { description "Prefix SID attribute"; leaf label-index { Majumdar, et al. Expires January 8, 2020 [Page 9] Internet-Draft Yang Model for BGP Segment Routing July 2019 type uint32; description "Label Index TLV carried with Prefix SID"; } container originator-srgb { description "SRGB info of the originating node, as signaled in the originator SRGB TLV"; list srgb-ranges { key "srgb-min srgb-max"; description "Concatenated ranges building the SRGB block"; leaf srgb-min { type rt-types:mpls-label; description "Range min"; } leaf srgb-max { type rt-types:mpls-label; description "Range max"; } } } } } // // SR Egress Peer Engineering (EPE) related groupings // grouping epe-sid-alloc-mode { description "Common grouping for EPE mode and SID"; leaf sid-allocation-type { type enumeration { enum EXPLICIT { description "EPE SID is configured"; } enum DYNAMIC { description "EPE SID is generated by node"; } } default "DYNAMIC"; description "SID allocation mode specifies whether the EPE SID is explicitly configured value, or a dynamically allocated value by the node. This applicable for EPE peer SID, EPE peer adjacency SID and Peer set SID, depending on the context it is configured."; } leaf explicit-sid { //when "../mode = 'EXPLICIT'"; type sid-type; Majumdar, et al. Expires January 8, 2020 [Page 10] Internet-Draft Yang Model for BGP Segment Routing July 2019 description "Explicitly configured EPE SID value, when the sid-allocation-type is EXPLICIT"; } leaf allocated-sid { type sid-type; config false; description "EPE SID value allocated by the node. When the sid allocation type is DYNAMIC, this would be a SID allocated by the node. In the case of EXPLICIT allocation type, this would typically be the explicit sid value configured by the user"; } } grouping epe-backup-info { description "Parameters for EPE backup SID selection"; container backup { description "Backup policy for this EPE"; leaf active { type boolean; config false; description "Boolean indicating if the backup as per requested policy is active for this EPE. Typically when EPE Peer, Link or Set is down, backup SID as per backup policy, would become active"; } leaf backup-type { type enumeration { enum PeerNodeSid { description "Backup via another Peer Node SID to the same AS. A Peer identifier is also required when this backup-type is selected"; } enum PeerAdjSid { description "Backup via remaining Peer Adjacencies to the same peer"; } enum PeerSetSid { description "Backup via Remaining PeerNode SIDs in the same PeerSet"; } enum IGP { description "Pop the EPE SID and perform IP lookup"; } } default "IGP"; description "Type of the backup for this EPE"; Majumdar, et al. Expires January 8, 2020 [Page 11] Internet-Draft Yang Model for BGP Segment Routing July 2019 reference "TBD"; } leaf backup-peer { //when "../backup-type = 'PeerNodeSid'"; type inet:ip-address; description "Peer identifier for the case when backup type is PeerNodeSid"; } leaf backup-sid { type sid-type; description "Backup SID (of a EPE Peer, Peer Adjacency or Peer-Set) to be used as backup for this EPE"; } } } grouping epe-config { description "Egress Peer Engineering (EPE) config grouping"; container egress-peer-engineering { description "Egress Peer Engineering (EPE) config under BGP Peer"; uses epe-sid-alloc-mode; leaf peer-set-name { type string; description "Make this EPE peer a member of the named Peer Set."; } uses epe-backup-info; list peer-adjacency { key first-hop-ipaddress; description "EPE parameters for the adjacency links over which multi-hop peering is setup"; leaf first-hop-ipaddress { type inet:ip-address; description "First hop IP address of the link"; } leaf first-hop-interface { type string; config false; description "The interface corresponding to the link"; Majumdar, et al. Expires January 8, 2020 [Page 12] Internet-Draft Yang Model for BGP Segment Routing July 2019 } uses epe-sid-alloc-mode; uses epe-backup-info; } } } grouping route-key-leafs { description "Grouping for key leafs identifying a route"; leaf prefix { type union { type inet:ip-prefix; type string; } description "BGP Prefix. This is a temp definition to cover ip-prefix and other NLRI formats. Import the type once defined in base BGP RIB model"; } leaf neighbor { type inet:ip-address; description "BGP Neighbor"; } leaf add-path-id { type uint32; description "Add-path ID"; } } grouping common-bgp-route-grouping { description "BGP route list" ; container routes { config false; description "BGP Route in local RIB"; list route { key "prefix neighbor add-path-id"; description "BGP route list"; uses route-key-leafs; } } } grouping common-bgp-vpn-route-grouping { description "BGP route list" ; container routes { config false; description "BGP VPN Route in local RIB"; Majumdar, et al. Expires January 8, 2020 [Page 13] Internet-Draft Yang Model for BGP Segment Routing July 2019 list route { key "rd prefix neighbor add-path-id"; description "Route List"; leaf rd { type rt-types:route-distinguisher; description "Route Distinguisher"; } uses route-key-leafs; } } } // // BGP Specific Paramters // // Augment AF with route list augment "/rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/" + "bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:ipv4-unicast" { description "Augment BGP SAFI route"; uses common-bgp-route-grouping; } augment "/rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/" + "bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:ipv6-unicast" { description "Augment BGP SAFI route"; uses common-bgp-route-grouping; } augment "/rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/" + "bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:ipv4-labeled-unicast" { description "Augment BGP SAFI route"; uses common-bgp-route-grouping; } augment "/rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/" + "bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:ipv6-labeled-unicast" { description "Augment BGP SAFI route"; uses common-bgp-route-grouping; } augment "/rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/" + "bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:l3vpn-ipv4-unicast" { description "Augment BGP SAFI route"; uses common-bgp-vpn-route-grouping; Majumdar, et al. Expires January 8, 2020 [Page 14] Internet-Draft Yang Model for BGP Segment Routing July 2019 } augment "/rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/" + "bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:l3vpn-ipv6-unicast" { description "Augment BGP SAFI route"; uses common-bgp-vpn-route-grouping; } // SR Prefix SID Related. // Prefix SID label index config via Route Policy augment "/rpol:routing-policy/" + "rpol:policy-definitions/rpol:policy-definition/" + "rpol:statements/rpol:statement/" + "rpol:actions/rpol:policy-result" { description "BGP policy actions to set label index"; leaf set-label-index { type uint32; description "Label Index"; } } // Prefix SID label in SAFI route augment "/rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/" + "bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:ipv4-labeled-unicast/" + "ietf-bgp-sr:routes/ietf-bgp-sr:route" { description "Augment BGP AF Table for SR prefix sid Labels info"; uses sr-route-prefix-sid; } augment "/rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/" + "bgp:bgp/bgp:global/bgp:afi-safis/bgp:afi-safi/bgp:ipv6-labeled-unicast/" + "ietf-bgp-sr:routes/ietf-bgp-sr:route" { description "Augment BGP AF Table for SR prefix sid Labels info"; uses sr-route-prefix-sid; } // Egress Peer Engineering (EPE) related. // EPE config under neighbor augment "/rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/" + "bgp:bgp/bgp:neighbors/bgp:neighbor" { description "Egress Peer Engineering data"; uses epe-config; } augment "/rt:routing/rt:control-plane-protocols/rt:control-plane-protocol/" + "bgp:bgp/bgp:peer-groups/bgp:peer-group" { Majumdar, et al. Expires January 8, 2020 [Page 15] Internet-Draft Yang Model for BGP Segment Routing July 2019 description "Egress Peer Engineering data"; uses epe-config; } } 5. Contributors Dhanendra Jain Cisco Systems US Email: dhanendra.ietf@gmail.com Zhichun Jiang Cisco Systems US Email: zcjiang@tencent.com Zafar Ali Cisco Systems US Email: zali@cisco.com Sharmila Palani Cisco Systems US Email: spalani@cisco.com 6. IANA Considerations 7. Security Considerations The transport protocol used for sending the BGP Segment Routing data MUST support authentication and SHOULD support encryption. The data- model by itself does not create any security implications. This draft does not change any underlying security issues inherent in [I-D.ietf-idr-bgp-model]. Majumdar, et al. Expires January 8, 2020 [Page 16] Internet-Draft Yang Model for BGP Segment Routing July 2019 8. Acknowledgements TBD. 9. References 9.1. Normative References [I-D.ietf-idr-bgp-model] Jethanandani, M., Patel, K., and S. Hares, "BGP YANG Model for Service Provider Networks", draft-ietf-idr-bgp- model-06 (work in progress), June 2019. [I-D.ietf-idr-bgp-prefix-sid] Previdi, S., Filsfils, C., Lindem, A., Sreekantiah, A., and H. Gredler, "Segment Routing Prefix SID extensions for BGP", draft-ietf-idr-bgp-prefix-sid-27 (work in progress), June 2018. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [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, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [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, . 9.2. Informative References Majumdar, et al. Expires January 8, 2020 [Page 17] Internet-Draft Yang Model for BGP Segment Routing July 2019 [I-D.ietf-spring-segment-routing-central-epe] Filsfils, C., Previdi, S., Dawra, G., Aries, E., and D. Afanasiev, "Segment Routing Centralized BGP Egress Peer Engineering", draft-ietf-spring-segment-routing-central- epe-10 (work in progress), December 2017. [I-D.ietf-spring-srv6-network-programming] Filsfils, C., Camarillo, P., Leddy, J., daniel.voyer@bell.ca, d., Matsushima, S., and Z. Li, "SRv6 Network Programming", draft-ietf-spring-srv6-network- programming-01 (work in progress), July 2019. [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", RFC 7951, DOI 10.17487/RFC7951, August 2016, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., Decraene, B., Litkowski, S., and R. Shakir, "Segment Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, July 2018, . [RFC8407] Bierman, A., "Guidelines for Authors and Reviewers of Documents Containing YANG Data Models", BCP 216, RFC 8407, DOI 10.17487/RFC8407, October 2018, . Authors' Addresses Kausik Majumdar Cisco 170 W. Tasman Drive San Jose, CA 95134 USA Email: kmajumda@cisco.com Kamran Raza Cisco 2000 Innovation Drive Kanata, ON K2K-3E8 CA Email: skraza@cisco.com Majumdar, et al. Expires January 8, 2020 [Page 18] Internet-Draft Yang Model for BGP Segment Routing July 2019 Bruno Decraene Orange France Email: bruno.decraene@orange.com Majumdar, et al. Expires January 8, 2020 [Page 19]