MPLS Working Group T. Saad Internet-Draft Juniper Networks Intended status: Standards Track R. Gandhi Expires: September 9, 2019 Cisco Systems, Inc. X. Liu Volta Networks V. Beeram Juniper Networks I. Bryskin Huawei Technologies March 08, 2019 A YANG Data Model for MPLS Static LSPs draft-ietf-mpls-static-yang-09 Abstract This document contains the specification for the MPLS Static Label Switched Paths (LSPs) YANG model. The model allows for the provisioning of static LSP(s) on Label Edge Router(s) LER(s) and Label Switched Router(s) LSR(s) devices along a LSP path without the dependency on any signaling protocol. The MPLS Static LSP model augments the MPLS base YANG model with specific data to configure and manage MPLS Static LSP(s). 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 September 9, 2019. Copyright Notice Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved. Saad, et al. Expires September 9, 2019 [Page 1] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Acronyms and Abbreviations . . . . . . . . . . . . . . . 3 2. MPLS Static LSP Model . . . . . . . . . . . . . . . . . . . . 3 2.1. Model Organization . . . . . . . . . . . . . . . . . . . 4 2.2. Model Tree Diagram . . . . . . . . . . . . . . . . . . . 4 2.3. Model Overview . . . . . . . . . . . . . . . . . . . . . 6 2.4. Model YANG Module(s) . . . . . . . . . . . . . . . . . . 7 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 4. Security Considerations . . . . . . . . . . . . . . . . . . . 15 5. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 16 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 6.1. Normative References . . . . . . . . . . . . . . . . . . 16 6.2. Informative References . . . . . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 1. Introduction This document describes a YANG [RFC7950] data model for configuring and managing the Multiprotocol Label Switching (MPLS) [RFC3031] Static LSPs. The model allows the configuration of LER and LSR devices with the necessary MPLS cross-connects or bindings to realize an end-to-end LSP service. A static LSP is established by manually specifying incoming and outgoing MPLS label(s) and necessary forwarding information on each of the traversed LER and LSR devices (ingress, transit, or egress nodes) of the forwarding path. For example, on an ingress LER device, the model is used to associate a specific Forwarding Equivalence Class (FEC) of packets- e.g. matching a specific IP prefix in a Virtual Routing or Forwarding (VRF) instance- to an MPLS outgoing label imposition, next-hop(s) and respective outgoing interface(s) to forward the packet. On an LSR device, the model is used to create a binding that swaps the incoming label with an outgoing label and forwards the packet on one or Saad, et al. Expires September 9, 2019 [Page 2] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 multiple egress path(s). On an egress LER, it is used to create a binding that decapsulates the incoming MPLS label and performs forwarding based on the inner MPLS label (if present) or IP forwarding in the packet. The MPLS Static LSP YANG model is broken into two modules "ietf-mpls- static" and "ietf-mpls-static-extended". The "ietf-mpls-static" module covers basic features for the configuration and management of unidirectional Static LSP(s), while "ietf-mpls-static-extended" covers extended features like the configuration and management of bidirectional Static LSP(s) and LSP admission control. The module "ietf-mpls-static" augments the MPLS Base YANG model defined in module "ietf-mpls" in [I-D.ietf-mpls-base-yang]. 1.1. Terminology 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. The terminology for describing YANG data models is found in [RFC7950]. 1.2. Acronyms and Abbreviations MPLS: Multiprotocol Label Switching LSP: Label Switched Path LSR: Label Switching Router LER: Label Edge Router FEC: Forwarding Equivalence Class NHLFE: Next Hop Label Forwarding Entry ILM: Incoming Label Map 2. MPLS Static LSP Model Saad, et al. Expires September 9, 2019 [Page 3] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 2.1. Model Organization The base MPLS Static LSP model covers the core features with the minimal set of configuration parameters needed to manage and operate MPLS Static LSPs. Additional MPLS Static LSP parameters as well as optional feature(s) are grouped in a separate MPLS Static LSP extended model. The relationship between the MPLS base and other MPLS modules are shown in Figure 1. Routing module +---------------+ v: import | ietf-routing | o: augment +---------------+ o | v MPLS base +-----------+ v: import module | ietf-mpls | o: augment +-----------+ o o | \ v v +------------------+ +--------------------+ MPLS Static | ietf-mpls-static | | ietf-mpls-ldp.yang | . . . LSP module +------------------+ +--------------------+ o | v +---------------------------+ Extended MPLS | ietf-mpls-static-extended | Static LSP +---------------------------+ module Figure 1: Relationship between MPLS modules 2.2. Model Tree Diagram The MPLS Static and extended LSP tree diagram as per [RFC8340] is shown in Figure 2. module: ietf-mpls-static augment /rt:routing/mpls:mpls: +--rw static-lsps +--rw static-lsp* [name] | +--rw name string | +--rw operation? mpls:mpls-operations-type Saad, et al. Expires September 9, 2019 [Page 4] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 | +--rw in-segment | | +--rw fec | | +--rw (type)? | | | +--:(ip-prefix) | | | | +--rw ip-prefix? inet:ip-prefix | | | +--:(mpls-label) | | | +--rw incoming-label? rt-types:mpls-label | | +--rw incoming-interface? if:interface-ref | +--rw out-segment | +--rw (out-segment)? | +--:(nhlfe-single) | | +--rw nhlfe-single | | +--rw mpls-label-stack | | | +--rw entry* [id] | | | +--rw id uint8 | | | +--rw label? rt-types:mpls-label | | | +--rw ttl? uint8 | | | +--rw traffic-class? uint8 | | +--rw outgoing-interface? if:interface-ref | +--:(nhlfe-multiple) | +--rw nhlfe-multiple | +--rw nhlfe* [index] | +--rw index string | +--rw backup-index? string | +--rw loadshare? uint16 | +--rw role? nhlfe-role | +--rw mpls-label-stack | | +--rw entry* [id] | | +--rw id uint8 | | +--rw label? | | | rt-types:mpls-label | | +--rw ttl? uint8 | | +--rw traffic-class? uint8 | +--rw outgoing-interface? if:interface-ref +--rw mpls-static-ext:bandwidth? uint32 +--rw mpls-static-ext:lsp-priority-setup? uint8 +--rw mpls-static-ext:lsp-priority-hold? uint8 module: ietf-mpls-static-extended augment /rt:routing/mpls:mpls: +--rw bidir-static-lsps +--rw bidir-static-lsp* [name] +--rw name string +--rw forward-lsp? mpls-static:static-lsp-ref +--rw reverse-lsp? mpls-static:static-lsp-ref Figure 2: MPLS Static LSP tree diagram Saad, et al. Expires September 9, 2019 [Page 5] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 2.3. Model Overview This document defines two YANG modules for MPLS Static LSP(s) configuration and management: ietf-mpls-static.yang and ietf-mpls- static-extended.yang. The ietf-mpls-static module contains the following high-level types and groupings: static-lsp-ref: A YANG reference type for a static LSP that can be used by data models to reference a configured static LSP. in-segment: A YANG grouping that describes parameters of an incoming class of FEC associated with a specific LSP as described in the MPLS architecture document [RFC3031]. The model allows the following types of traffic to be mapped onto the static LSP on an ingress LER: o Unlabeled traffic destined to a specific prefix o Labeled traffic arriving with a specific label o Traffic carried on a TE tunnel whose LSP is statically created via this model. out-segment: A YANG grouping that describes parameters for the forwarding path(s) and their associated attributes for an LSP. The model allows for the following cases: o single forwarding path or NHLFE o multiple forwarding path(s) or NHLFE(s), each of which can serve a primary, backup or both role(s). The ietf-mpls-static-extended module contains the following high- level types and groupings: bidir-static-lsp: A YANG grouping that describes list of static bidirectional LSPs The ietf-mpls-static-extended augments the ietf-mpls-static model with additional parameters to configure and manage: o Bidirectional Static LSP(s) Saad, et al. Expires September 9, 2019 [Page 6] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 o Defining Static LSP bandwidth allocation o Defining Static LSP preemption priorities 2.4. Model YANG Module(s) Configuring LSPs through an LSR/LER involves the following steps: o Enabling MPLS on MPLS capable interfaces. o Configuring in-segments and out-segments on LER(s) and LSR(s) traversed by the LSP. o Setting up the cross-connect per LSP to associate segments and/or to indicate connection origination and termination. o Optionally specifying label stack actions. o Optionally specifying segment traffic parameters. The objects covered by this model are derived from the Incoming Label Map (ILM) and Next Hop Label Forwarding Entry (NHLFE) as specified in the MPLS architecture document [RFC3031]. The ietf-mpls-static module imports the followinig modules: o ietf-inet-types defined in [RFC6991] o ietf-routing defined in [RFC8349] o ietf-routing-types defined in [RFC8294] o ietf-interfaces defined in [RFC8343] o ietf-mpls defined in [I-D.ietf-mpls-base-yang] o ietf-te defined in [I-D.ietf-teas-yang-te] The ietf-mpls-static module is shown below: file "ietf-mpls-static@2019-03-08.yang" module ietf-mpls-static { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-mpls-static"; prefix "mpls-static"; import ietf-mpls { prefix "mpls"; Saad, et al. Expires September 9, 2019 [Page 7] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 reference "draft-ietf-mpls-base-yang: MPLS Base YANG Data Model"; } import ietf-routing { prefix "rt"; reference "RFC8349: A YANG Data Model for Routing Management"; } import ietf-routing-types { prefix "rt-types"; reference "RFC8294: Common YANG Data Types for the Routing Area"; } import ietf-inet-types { prefix inet; reference "RFC6991: Common YANG Data Types"; } import ietf-interfaces { prefix "if"; reference "RFC7223: A YANG Data Model for Interface Management"; } organization "IETF MPLS Working Group"; contact "WG Web: WG List: WG Chair: Loa Andersson WG Chair: Nic Leymann Editor: Tarek Saad Editor: Kamran Raza Editor: Rakesh Gandhi Editor: Xufeng Liu Saad, et al. Expires September 9, 2019 [Page 8] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 Editor: Vishnu Pavan Beeram Editor: Himanshu Shah Editor: Igor Bryskin "; description "This YANG module augments the 'ietf-routing' module with basic configuration and operational state data for MPLS static The model fully conforms to the Network Management Datastore Architecture (NMDA). Copyright (c) 2018 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; see the RFC itself for full legal notices."; // RFC Ed.: replace XXXX with actual RFC number and remove this // note. // RFC Ed.: update the date below with the date of RFC publication // and remove this note. revision "2019-03-08" { description "Latest revision of MPLS Static LSP YANG module"; reference "RFC XXXX: A YANG Data Model for MPLS Static LSPs"; } typedef static-lsp-ref { type leafref { path "/rt:routing/mpls:mpls/mpls-static:static-lsps/" + "mpls-static:static-lsp/mpls-static:name"; } description "This type is used by data models that need to reference configured static LSP."; } Saad, et al. Expires September 9, 2019 [Page 9] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 grouping in-segment { description "In-segment grouping"; container in-segment { description "MPLS incoming segment"; container fec { description "Forwarding Equivalence Class grouping"; choice type { description "FEC type choices"; case ip-prefix { leaf ip-prefix { type inet:ip-prefix; description "An IP prefix"; } } case mpls-label { leaf incoming-label { type rt-types:mpls-label; description "label value on the incoming packet"; } } } leaf incoming-interface { type if:interface-ref; description "Optional incoming interface if FEC is restricted to traffic incoming on a specific interface"; } } } } grouping out-segment { description "Out-segment grouping"; container out-segment { description "MPLS outgoing segment"; choice out-segment { description "The MPLS out-segment type choice"; case nhlfe-single { container nhlfe-single { description "Container for single NHLFE entry"; uses mpls:nhlfe-single-contents; leaf outgoing-interface { type if:interface-ref; description "The outgoing interface"; } } } Saad, et al. Expires September 9, 2019 [Page 10] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 case nhlfe-multiple { container nhlfe-multiple { description "Container for multiple NHLFE entries"; list nhlfe { key index; description "MPLS NHLFE entry"; uses mpls:nhlfe-multiple-contents; leaf outgoing-interface { type if:interface-ref; description "The outgoing interface"; } } } } } } } augment "/rt:routing/mpls:mpls" { description "Augmentations for MPLS Static LSPs"; container static-lsps { description "Statically configured LSPs, without dynamic signaling"; list static-lsp { key name; description "list of defined static LSPs"; leaf name { type string; description "name to identify the LSP"; } leaf operation { type mpls:mpls-operations-type; description "The MPLS operation to be executed on the incoming packet"; } uses in-segment; uses out-segment; } } } } The ietf-mpls-static-extended module imports the followinig modules: o ietf-mpls defined in [I-D.ietf-mpls-base-yang] Saad, et al. Expires September 9, 2019 [Page 11] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 o ietf-mpls-static defined in this document o ietf-routing defined in [RFC8349] The ietf-mpls-static-extended module is shown below: file "ietf-mpls-static-extended@2019-03-08.yang" module ietf-mpls-static-extended { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-mpls-static-extended"; prefix "mpls-static-ext"; import ietf-mpls { prefix "mpls"; reference "draft-ietf-mpls-base-yang: MPLS Base YANG Data Model"; } import ietf-routing { prefix "rt"; reference "RFC8349: A YANG Data Model for Routing Management"; } import ietf-mpls-static { prefix "mpls-static"; reference "RFC XXXX: A YANG Data Model for MPLS Static LSPs"; } organization "IETF MPLS Working Group"; contact "WG Web: WG List: WG Chair: Loa Andersson WG Chair: Nic Leymann Editor: Tarek Saad Editor: Kamran Raza Editor: Rakesh Gandhi Saad, et al. Expires September 9, 2019 [Page 12] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 Editor: Xufeng Liu Editor: Vishnu Pavan Beeram Editor: Himanshu Shah Editor: Igor Bryskin "; description "This YANG module contains the Extended MPLS Static LSP YANG data model. The model fully conforms to the Network Management Datastore Architecture (NMDA). Copyright (c) 2018 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; see the RFC itself for full legal notices."; // RFC Ed.: replace XXXX with actual RFC number and remove this // note. // RFC Ed.: update the date below with the date of RFC publication // and remove this note. revision "2019-03-08" { description "Latest revision of MPLS Static LSP Extended YANG module"; reference "RFC XXXX: A YANG Data Model for MPLS Static LSPs"; } grouping bidir-static-lsp { description "grouping for top level list of static bidirectional LSPs"; leaf forward-lsp { type mpls-static:static-lsp-ref; description "Reference to a configured static forward LSP"; Saad, et al. Expires September 9, 2019 [Page 13] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 } leaf reverse-lsp { type mpls-static:static-lsp-ref; description "Reference to a configured static reverse LSP"; } } augment "/rt:routing/mpls:mpls/mpls-static:static-lsps" { description "Augmentation for static MPLS LSPs"; leaf bandwidth { type uint32; units "Mbps"; description "Bandwidth in Mbps, e.g., using offline calculation"; } leaf lsp-priority-setup { type uint8 { range "0..7"; } description "LSP setup priority"; } leaf lsp-priority-hold { type uint8 { range "0..7"; } description "LSP hold priority"; } } augment "/rt:routing/mpls:mpls" { description "Augmentations for MPLS Static LSPs"; container bidir-static-lsps { description "Statically configured bidirectional LSPs"; list bidir-static-lsp { key name; description "List of static bidirectional LSPs"; leaf name { type string; description "Name that identifies the bidirectional LSP"; } uses bidir-static-lsp; } } Saad, et al. Expires September 9, 2019 [Page 14] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 } } 3. IANA Considerations This document registers the following URIs 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-mpls-static Registrant Contact: The MPLS WG of the IETF. XML: N/A, the requested URI is an XML namespace. URI: urn:ietf:params:xml:ns:yang:ietf-mpls-static-extended Registrant Contact: The MPLS WG of the IETF. XML: N/A, the requested URI is an XML namespace. This document registers two YANG modules in the YANG Module Names registry [RFC6020]. name: ietf-mpls-static namespace: urn:ietf:params:xml:ns:yang:ietf-mpls-static prefix: ietf-mpls-static // RFC Ed.: replace XXXX with RFC number and remove this note reference: RFCXXXX name: ietf-mpls-static-extended namespace: urn:ietf:params:xml:ns:yang:ietf-mpls-static-extended prefix: ietf-mpls-static-extended // RFC Ed.: replace XXXX with RFC number and remove this note reference: RFCXXXX 4. Security Considerations The YANG modules specified in this document define schemas 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 [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. Saad, et al. Expires September 9, 2019 [Page 15] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 All nodes defined in this YANG module that are writable/creatable/ deletable (i.e., config true, which is the default) 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: o /ietf-routing:routing/ietf-mpls:mpls:/ietf-mpls:static-lsps: This entire subtree is related to security. An administrator needs to restrict write access to all configurable objects within this data model. 5. Contributors Himanshu Shah Ciena email: hshah@ciena.com Kamran Raza Cisco Systems, Inc. email: skraza@cisco.com 6. References 6.1. Normative References [I-D.ietf-mpls-base-yang] Saad, T., Raza, K., Gandhi, R., Liu, X., and V. Beeram, "A YANG Data Model for MPLS Base", draft-ietf-mpls-base- yang-10 (work in progress), February 2019. [I-D.ietf-teas-yang-te] Saad, T., Gandhi, R., Liu, X., Beeram, V., and I. Bryskin, "A YANG Data Model for Traffic Engineering Tunnels and Interfaces", draft-ietf-teas-yang-te-19 (work in progress), February 2019. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol Label Switching Architecture", RFC 3031, DOI 10.17487/RFC3031, January 2001, . Saad, et al. Expires September 9, 2019 [Page 16] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . [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, . [RFC8294] Liu, X., Qu, Y., Lindem, A., Hopps, C., and L. Berger, "Common YANG Data Types for the Routing Area", RFC 8294, DOI 10.17487/RFC8294, December 2017, . [RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, . [RFC8343] Bjorklund, M., "A YANG Data Model for Interface Management", RFC 8343, DOI 10.17487/RFC8343, March 2018, . Saad, et al. Expires September 9, 2019 [Page 17] Internet-Draft MPLS Static LSPs YANG Data Model March 2019 [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, . 6.2. Informative References [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, . Authors' Addresses Tarek Saad Juniper Networks Email: tsaad.net@gmail.com Rakesh Gandhi Cisco Systems, Inc. Email: rgandhi@cisco.com Xufeng Liu Volta Networks Email: xufeng.liu.ietf@gmail.com Vishnu Pavan Beeram Juniper Networks Email: vbeeram@juniper.net Igor Bryskin Huawei Technologies Email: Igor.Bryskin@huawei.com Saad, et al. Expires September 9, 2019 [Page 18]