Huawei Technologies

italo.busi@huawei.com

Futurewei Inc.

aihuaguo.ietf@gmail.com

Volta Networks

xufeng.liu.ietf@gmail.com

Juniper Networks

tsaad@juniper.net

Cisco Systems, Inc.

rgandhi@cisco.com

TEAS Working Group This document describes a YANG data model for Multi-Protocol Label Switching (MPLS) with Traffic Engineering (MPLS-TE) networks.

Introduction This document describes a YANG data model for Multi-Protocol Label Switching (MPLS) with Traffic Engineering (MPLS-TE) networks. This document also defines a collection of common data types and groupings in YANG data modeling language for MPLS-TE networks. These derived common types and groupings are intended to be imported by the MPLS-TE topology model, defined in this document, as well as by the MPLS-TE tunnel model, defined in . Multi-Protocol Label Switching - Transport Profile (MPLS-TP) is a profile of the MPLS protocol that is used in packet switched transport networks and operated in a similar manner to other existing transport technologies (e.g., OTN), as described in . The YANG model defined in this document can also be for MPLS-TP networks.

Tree Diagram A simplified graphical representation of the data model is used in of this this document. The meaning of the symbols in these diagrams is defined in .

Prefixes in Data Node Names In this document, names of data nodes and other data model objects are prefixed using the standard prefix associated with the corresponding YANG imported modules, as shown in . Prefix YANG module Reference rt-types ietf-routing-types tet ietf-te-topology tet-pkt ietf-te-topology-packet te-packet-types ietf-te-packet-types mte-types ietf-mpls-te-types This document tet-mpls ietf-te-mpls-topology This document

MPLS-TE Types Overview The module ietf-mpls-te-types contains the following YANG types and groupings which can be reused by MPLS-TE YANG models:

load-balancing-type

This identify defines the types of load-balancing algorithms used on bundled MPLS-TE link.

te-mpls-label-hop

This grouping is used for the augmentation of TE label for MPLS-TE path.

MPLS-TE Topology Model Overview The MPLS-TE technology specific topology model augments the ietf-te- topology-packet YANG module, defined in , which in turns augment the generic ietf-te-topology YANG module, defined in , as shown in .

Given the guidance for augmentation in , the following technology-specific augmentations need to be provided: A network-type to indicate that the TE topology is an MPLS-TE Topology, as follow:

TE Label Augmentations as described in . Note: TE Bandwidth Augmentations for paths, LSPs and links are provided by the ietf-te-topology-packet module, defined in .

TE Label Augmentations In MPLS-TE, the label allocation is done by NE, information about label values availability is not necessary to be provided to the controller. Moreover, MPLS-TE tunnels are currently established within a single domain. Therefore this document does not define any MPLS-TE technology-specific augmentations, of the TE Topology model, for the TE label since no TE label related attributes should be instantiated for MPLS-TE Topologies. Open issue: shall this module allows the setup of MPLS-TE multi-domain tunnels?

MPLS-TP Topology Multi-Protocol Label Switching - Transport Profile (MPLS-TP) is a profile of the MPLS protocol that is used in packet switched transport networks and operated in a similar manner to other existing transport technologies (e.g., OTN), as described in . Therefore YANG model defined in this document can also be applicable for MPLS-TP networks. However, as described in , MPLS-TP networks support bidirectional LSPs and require no ECMP and no PHP. When reporting the topology for an MPLS-TP network, additional information is required to indicate whether the network support these MPLS-TP characteristics. It is worth noting that is already capable to model TE topologies supporting either unidirectional or bidirectional LSPs: all bidirectional TE links can support bidirectional LSPs and all the links can support unidirectional LSPs and it is always possible to associated unidirectional LSPs as long as they belong to the same tunnel. When setting up bidirectional LSPs (e.g., MPLS-TP LSPs) only bidirectional TE Links are selected by path computation. In order to allow reporting that ECMP is not affecting forwarding the packets of a given LSP, the load-balancing-type attribute reports whether a LAG or TE Bundled Link performs load-balancing on a per-flow or per-top-label:

When setting up LSPs which do not requires ECMP (e.g., MPLS-TP LSPs) only Links that are not part of a LAG or TE Bundle or that performs per-top-label load balancing are selected by path computation. It is assumed that almost all the MPLS-TE nodes are capable to support Ultimate Hop Popping (UHP). However, if some interfaces are not able to support UHP, they can report it in the MPLS-TE topology:

When setting up LSPs which do not requires PHP (e.g., MPLS-TP LSPs) only the interfaces (LTPs) which are capable to support UHP in the destination node are selected by path computation.

YANG model for common MPLS-TE Types

file "ietf-mpls-te-types@2021-10-12.yang" module ietf-mpls-te-types { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-mpls-te-types"; prefix "mte-types"; import ietf-routing-types { prefix "rt-types"; } organization "Internet Engineering Task Force (IETF) TEAS WG"; contact "WG Web: WG List: Editor: Italo Busi Editor: Haomian Zheng Editor: Aihua Guo Editor: Xufeng Liu Editor: Vishnu Pavan Beeram Editor: Tarek Saad Editor: Rakesh Gandhi Editor: Igor Bryskin Editor: Yanlei Zheng "; description "This module defines technology-specific MPLS-TE types data model. Copyright (c) 2021 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 (http://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision 2021-10-12 { description "Initial Version"; reference "draft-busizheng-teas-yang-te-mpls-topology-02"; } /* * Typedefs */ typedef load-balancing-type { type enumeration { enum per-flow { description "The load-balancing algorithm ensures that packets characterized as the same flow (e.g. based on IP 5-tuple) that egress on a LAG or a bundled TE link are forwarded on the same component link. Packets for different flows within the same LSP can be forwarded on different component links."; } enum per-top-label { description "The load-balancing algorithm ensures incoming MPLS packets with the same top MPLS label and that egress on on a LAG or bundled TE link are forwarded on the same component link. Packets for different flows within the same LSP are forwarded on the same component link."; } } description "The type of load balancing used on bundled links."; } // typedef load-balancing-type /* * Groupings */ grouping te-mpls-label-hop { description "MPLS-TE Label Hop."; leaf mpls-label { type rt-types:mpls-label; description "MPLS Label."; } } // grouping te-mpls-label-hop } ]]>

YANG model for MPLS-TE Topology

YANG Tree below shows the tree diagram of the YANG model defined in module ietf-te-mpls-topology.yang.

YANG Code

file "ietf-te-mpls-topology@2021-07-12.yang" module ietf-te-mpls-topology { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-te-mpls-topology"; prefix "tet-mpls"; import ietf-network { prefix "nw"; } import ietf-network-topology { prefix "nt"; } import ietf-te-topology { prefix "tet"; } import ietf-te-topology-packet { prefix "tet-pkt"; } import ietf-mpls-te-types { prefix "mte-types"; } organization "Internet Engineering Task Force (IETF) TEAS WG"; contact "WG Web: WG List: Editor: Italo Busi Editor: Haomian Zheng Editor: Aihua Guo Editor: Xufeng Liu Editor: Vishnu Pavan Beeram Editor: Tarek Saad Editor: Rakesh Gandhi Editor: Igor Bryskin Editor: Yanlei Zheng "; description "This module defines technology-specific MPLS-TE topology data model. Copyright (c) 2021 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 (http://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision 2021-10-12 { description "Initial Version"; reference "draft-busizheng-teas-yang-te-mpls-topology-02"; } /* * Augmentations */ augment "/nw:networks/nw:network/nw:network-types/" + "tet:te-topology/tet-pkt:packet" { description "Augment network types to include MPLS-TE Topology Type"; container mpls-topology { presence "Indicates an MPLS-TE Topology Type."; description "Its presence indicates an MPLS-TE Topology"; } } augment "/nw:networks/nw:network/nt:link/tet:te" { when "../../nw:network-types/tet:te-topology/" + "tet-pkt:packet/tet-mpls:mpls-topology" { description "Augment MPLS-TE Topology."; } description "Augment TE Link."; leaf load-balancing-type { type mte-types:load-balancing-type; default 'per-flow'; description "Indicates the type of load-balancing (per-flow or per-LSP) performed by the bundled TE Link. This leaf is not present when the TE Link is not bundled."; } // leaf load-balancing-type } augment "/nw:networks/nw:network/nw:node/nt:termination-point/" + "tet:te" { when "../../../nw:network-types/tet:te-topology/" + "tet-pkt:packet/tet-mpls:mpls-topology" { description "Augment MPLS-TE Topology."; } description "Augment LTP."; leaf uhp-incapable { type empty; config false; description "When present, indicates that the LTP is not capable to support Ultimate Hop Popping (UHP)."; } // leaf uhp-incapable } } ]]>

Security Considerations To be added.

IANA Considerations To be added.

This document captures the current syntax used in YANG module tree diagrams. The purpose of this document is to provide a single location for this definition. This syntax may be updated from time to time based on the evolution of the YANG language. This document defines a collection of common data types using the YANG data modeling language. These derived common types are designed to be imported by other modules defined in the routing area. This document defines a YANG data model for representing, retrieving, and manipulating Traffic Engineering (TE) Topologies. The model serves as a base model that other technology-specific TE topology models can augment. Volta Networks Individual Juniper Networks Juniper Networks Ciena Telefonica This document defines a YANG data model for layer 3 traffic engineering topologies. Juniper Networks Cisco Systems Inc Volta Networks Juniper Networks Individual This document defines a YANG data model for the configuration and management of Multiprotocol Label Switching (MPLS) Traffic Engineering (TE) tunnels, Label Switched Paths (LSPs) and interfaces. The model augments the TE generic YANG model for MPLS packet dataplane technology. This model covers data for configuration, operational state, remote procedural calls, and event notifications. This document specifies an architectural framework for the application of Multiprotocol Label Switching (MPLS) to the construction of packet-switched transport networks. It describes a common set of protocol functions -- the MPLS Transport Profile (MPLS-TP) -- that supports the operational models and capabilities typical of such networks, including signaled or explicitly provisioned bidirectional connection-oriented paths, protection and restoration mechanisms, comprehensive Operations, Administration, and Maintenance (OAM) functions, and network operation in the absence of a dynamic control plane or IP forwarding support. Some of these functions are defined in existing MPLS specifications, while others require extensions to existing specifications to meet the requirements of the MPLS-TP.This document defines the subset of the MPLS-TP applicable in general and to point-to-point transport paths. The remaining subset, applicable specifically to point-to-multipoint transport paths, is outside the scope of this document.This document is a product of a joint Internet Engineering Task Force (IETF) / International Telecommunication Union Telecommunication Standardization Sector (ITU-T) effort to include an MPLS Transport Profile within the IETF MPLS and Pseudowire Emulation Edge-to-Edge (PWE3) architectures to support the capabilities and functionalities of a packet transport network as defined by the ITU-T. This document is not an Internet Standards Track specification; it is published for informational purposes.

Acknowledgments We thank Loa Andersson for providing useful suggestions for this draft. This document was prepared using kramdown. Previous versions of this document was prepared using 2-Word-v2.0.template.dot.

Contributors Huawei Technologies

zhenghaomian@huawei.com

Juniper Networks

vbeeram@juniper.net

Individual

i_bryskin@yahoo.com

China Unicom

zhengyanlei@chinaunicom.cn