Juniper Networks

tsaad@juniper.net

Cisco Systems, Inc.

skraza@cisco.com

Cisco Systems, Inc.

rgandhi@cisco.com

Volta Networks

xufeng.liu.ietf@gmail.com

Juniper Networks

vbeeram@juniper.net

MPLS YANG Data Model MPLS Model MPLS RIB MPLS Routing Information Base This document contains a specification of the MPLS base YANG data model. The MPLS base YANG data model serves as a base framework for configuring and managing an MPLS switching subsystem on an MPLS-enabled router. It is expected that other MPLS YANG data models (e.g., MPLS Label Switched Path (LSP) static, LDP, or RSVP-TE YANG data models) will augment the MPLS base YANG data model.

Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at .

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 () 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

• .  Introduction
  • .  Terminology
  • .  Acronyms and Abbreviations
• .  MPLS Base Model
  • .  Model Overview
  • .  Model Organization
  • .  Model Design
  • .  Model Tree Diagram
  • .  MPLS Base YANG Module
• .  IANA Considerations
• .  Security Considerations
• .  References
  • .  Normative References
  • .  Informative References
• .  Data Tree Instance Example
• Acknowledgments
• Contributors
• Authors' Addresses

Introduction A core routing YANG data model is defined in ; it provides a basis for the development of routing data models for specific Address Families (AFs). Specifically, defines a model for a generic Routing Information Base (RIB) that is AF agnostic. also defines two instances of RIBs based on the generic RIB model for IPv4 and IPv6 AFs. The MPLS base model defined in this document augments the generic RIB model defined in with additional data that enables MPLS forwarding for one or more specific destination prefixes present in one or more AF RIBs, as described in the MPLS architecture document . The MPLS base model also defines a new instance of the generic RIB YANG data model as defined in to store native MPLS routes. The native MPLS RIB instance stores one or more routes that are not associated with other AF instance RIBs (such as IPv4 or IPv6 instance RIBs) but are enabled for MPLS forwarding. Examples of such native MPLS routes are routes programmed by RSVP on one or more transit MPLS routers along the path of a Label Switched Path (LSP). Other examples are MPLS routes that cross-connect to specific Layer 2 adjacencies, such as Layer 2 Attachment Circuits (ACs); or Layer 3 adjacencies, such as Segment Routing (SR) Adjacency Segments (Adj-SIDs) as described in . The MPLS base YANG data model serves as a basis for future development of MPLS YANG data models covering MPLS features and subsystems that are more sophisticated. The main purpose is to provide essential building blocks for other YANG data models involving different control-plane protocols and MPLS functions. To this end, it is expected that the MPLS base data model will be augmented by a number of other YANG modules developed by the IETF (e.g., by the TEAS and MPLS Working Groups). The YANG module defined in this document conforms to the Network Management Datastore Architecture (NMDA) .

Terminology The terminology for describing YANG data models is found in .

Acronyms and Abbreviations

MPLS:

Multiprotocol Label Switching

RIB:

Routing Information Base

LSP:

Label Switched Path

LSR:

Label Switching Router

NHLFE:

Next Hop Label Forwarding Entry

MPLS Base Model This document describes the "ietf-mpls" YANG module, which provides base components of the MPLS data model. It is expected that other MPLS YANG modules will augment the "ietf-mpls" YANG module for other MPLS extensions to provision LSPs (e.g., MPLS static, MPLS LDP, or MPLS RSVP-TE LSPs).

Model Overview This document models MPLS-labeled routes as an augmentation of the generic routing RIB data model as defined in . For example, IP prefix routes (e.g., routes stored in IPv4 or IPv6 RIBs) are augmented to carry additional data to enable them for MPLS forwarding. This document also defines a new instance of the generic RIB model defined in to store one or more native MPLS routes (described further in ) by extending the identity "address-family" defined in with a new "mpls" identity; see .

Model Organization

Relationship between MPLS Modules Routing +---------------+ v: import YANG module | ietf-routing | o: augment +---------------+ o | v MPLS base +-----------+ v: import YANG module | ietf-mpls | o: augment +-----------+ o o------+ | \ v v +-------------------+ +---------------------+ MPLS static | ietf-mpls-static@ | | ietf-mpls-ldp.yang@ | . . LSP YANG +-------------------+ +---------------------+ module @: not in this document; shown for illustration only

The "ietf-mpls" YANG module defines the following identities:

mpls:

Identity that extends the "address-family" identity of RIB instances, as defined in , to represent the native MPLS RIB instance.

label-block-alloc-mode:

A base YANG identity for one or more supported label-block allocation modes.

The "ietf-mpls" YANG module contains the following high-level types and groupings:

mpls-operations-type:

An enumeration type that represents support for possible MPLS operation types (impose-and-forward, pop-and-forward, pop-impose-and-forward, and pop-and-lookup).

nhlfe-role:

An enumeration type that represents the role of the Next Hop Label Forwarding Entry (NHLFE).

nhlfe-single-contents:

A YANG grouping that describes a single NHLFE and its associated parameters as described in the MPLS architecture document . This grouping is specific to the case when a single next hop is associated with the route.

The NHLFE is used when forwarding a labeled packet. It contains the following information:

1. The packet's next hop. For "nhlfe-single-contents", only a single next hop is expected, while for "nhlfe-multiple-contents", multiple next hops are possible.
2. The operation to perform on the packet's label stack. This can be one of the following operations:
   1. Replace the label at the top of the label stack with one or more specified new labels.
   2. Pop the label stack.
   3. Replace the label at the top of the label stack with a specified new label, and then push one or more specified new labels onto the label stack.
   4. Push one or more labels onto an unlabeled packet.

The NHLFE may also contain:

1. The data-link encapsulation to use when transmitting the packet.
2. The way to encode the label stack when transmitting the packet.
3. Any other information needed in order to properly dispose of the packet.

nhlfe-multiple-contents:

A YANG grouping that describes a set of NHLFEs and their associated parameters as described in the MPLS architecture document . This grouping is used when multiple next hops are associated with the route.

interfaces-mpls:

A YANG grouping that describes the list of MPLS-enabled interfaces on a device.

label-blocks:

A YANG grouping that describes the list of assigned MPLS label blocks and their properties.

rib-mpls-properties:

A YANG grouping for the augmentation of the generic RIB with MPLS label forwarding data as defined in .

rib-active-route-mpls-input:

A YANG grouping for the augmentation to the "active-route" RPC that is specific to the MPLS RIB instance.

Model Design The MPLS routing model is based on the core routing data model defined in . shows the extensions introduced by the MPLS base model on defined RIBs.

Relationship between MPLS Model and RIB Instances +-----------------+ | MPLS base model | +-----------------+ ____/ | |_____ |________ / | \ \ / | \ \ o o o + +---------+ +---------+ +--------+ +-----------+ | RIB(v4) | | RIB(v6) | | RIB(x) | | RIB(mpls) | +---------+ +---------+ +--------+ +-----------+ +: created by the MPLS base model o: augmented by the MPLS base model

As shown in , the MPLS base YANG data model augments defined instances of AF RIBs with additional data that enables MPLS forwarding for destination prefixes stored in such RIBs. For example, an IPv4 prefix stored in RIB(v4) is augmented to carry an MPLS local label and one or more per-next-hop remote labels to enable MPLS forwarding for such a prefix. The MPLS base model also creates a separate instance of the generic RIB model defined in to store one or more MPLS native routes that are enabled for MPLS forwarding but are not stored in one or more other AF RIBs. Some examples of such native MPLS routes are:

• Routes programmed by RSVP on Label Switching Routers (LSRs) along the path of an LSP,
• Routes that cross-connect an MPLS local label to a Layer 2 or Layer 3 Virtual Routing and Forwarding (VRF) entity,
• Routes that cross-connect an MPLS local label to a specific Layer 2 adjacency or interface, such as Layer 2 Attachment Circuits (ACs), or
• Routes that cross-connect an MPLS local label to a Layer 3 adjacency or interface, such as MPLS Segment Routing (SR) Adjacency Segments (Adj-SIDs) or SR MPLS Binding SIDs as defined in .

Model Tree Diagram The MPLS base tree diagram, which follows the notation defined in , is shown in .

MPLS Base Tree Diagram module: ietf-mpls augment /rt:routing: +--rw mpls +--rw ttl-propagate? boolean +--rw mpls-label-blocks | +--rw mpls-label-block* [index] | +--rw index string | +--rw start-label? rt-types:mpls-label | +--rw end-label? rt-types:mpls-label | +--rw block-allocation-mode? identityref | +--ro inuse-labels-count? yang:gauge32 +--rw interfaces +--rw interface* [name] +--rw name if:interface-ref +--rw mpls-enabled? boolean +--rw maximum-labeled-packet? uint32 augment /rt:routing/rt:ribs/rt:rib/rt:routes/rt:route: +--ro mpls-enabled? boolean +--ro mpls-local-label? rt-types:mpls-label +--ro destination-prefix? -> ../mpls-local-label +--ro route-context? string augment /rt:routing/rt:ribs/rt:rib/rt:routes/rt:route/rt:next-hop /rt:next-hop-options/rt:simple-next-hop: +--ro mpls-label-stack +--ro entry* [id] +--ro id uint8 +--ro label? rt-types:mpls-label +--ro ttl? uint8 +--ro traffic-class? uint8 augment /rt:routing/rt:ribs/rt:rib/rt:routes/rt:route/rt:next-hop /rt:next-hop-options/rt:next-hop-list/rt:next-hop-list /rt:next-hop: +--ro index? string +--ro backup-index? string +--ro loadshare? uint16 +--ro role? nhlfe-role +--ro mpls-label-stack +--ro entry* [id] +--ro id uint8 +--ro label? rt-types:mpls-label +--ro ttl? uint8 +--ro traffic-class? uint8 augment /rt:routing/rt:ribs/rt:rib/rt:active-route/rt:input: +---w destination-address? -> ../mpls-local-label +---w mpls-local-label? rt-types:mpls-label augment /rt:routing/rt:ribs/rt:rib/rt:active-route/rt:output /rt:route/rt:next-hop/rt:next-hop-options /rt:simple-next-hop: +-- mpls-label-stack +-- entry* [id] +-- id uint8 +-- label? rt-types:mpls-label +-- ttl? uint8 +-- traffic-class? uint8 augment /rt:routing/rt:ribs/rt:rib/rt:active-route/rt:output /rt:route/rt:next-hop/rt:next-hop-options /rt:next-hop-list/rt:next-hop-list/rt:next-hop: +-- index? string +-- backup-index? string +-- loadshare? uint16 +-- role? nhlfe-role +-- mpls-label-stack +-- entry* [id] +-- id uint8 +-- label? rt-types:mpls-label +-- ttl? uint8 +-- traffic-class? uint8

MPLS Base YANG Module This section describes the "ietf-mpls" YANG module, which provides base components of the MPLS data model. Other YANG modules may import and augment the MPLS base module to add feature-specific data. The "ietf-mpls" YANG module imports the following YANG modules:

• "ietf-routing" as defined in
• "ietf-routing-types" as defined in
• "ietf-yang-types" as defined in
• "ietf-interfaces" as defined in

This YANG module also references the following RFCs in defining the types, YANG groupings, and other features of the YANG module: , , , , and .

MPLS Base YANG Module module ietf-mpls { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-mpls"; prefix mpls; import ietf-routing { prefix rt; reference "RFC 8349: A YANG Data Model for Routing Management (NMDA Version)"; } import ietf-routing-types { prefix rt-types; reference "RFC 8294: Common YANG Data Types for the Routing Area"; } 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"; } organization "IETF MPLS Working Group"; contact "WG Web: <https://datatracker.ietf.org/wg/mpls/> WG List: <mailto:mpls@ietf.org> Editor: Tarek Saad <mailto:tsaad@juniper.net> Editor: Kamran Raza <mailto:skraza@cisco.com> Editor: Rakesh Gandhi <mailto:rgandhi@cisco.com> Editor: Xufeng Liu <mailto:xufeng.liu.ietf@gmail.com> Editor: Vishnu Pavan Beeram <mailto:vbeeram@juniper.net>"; description "This YANG module defines the essential components for the management of the MPLS subsystem. The model fully conforms to the Network Management Datastore Architecture (NMDA). 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 8960; see the RFC itself for full legal notices."; revision 2020-12-18 { description "Initial revision."; reference "RFC 8960: A YANG Data Model for MPLS Base"; } /* Identities */ identity mpls { base rt:address-family; description "This identity represents the MPLS address family."; } identity mpls-unicast { base mpls:mpls; description "This identity represents the MPLS unicast address family."; } identity label-block-alloc-mode { description "Base identity for label-block allocation mode."; } identity label-block-alloc-mode-manager { base label-block-alloc-mode; description "Label-block allocation on the reserved block is managed by the label manager."; } identity label-block-alloc-mode-application { base label-block-alloc-mode; description "Label-block allocation on the reserved block is managed by the application."; } /** * Typedefs */ typedef mpls-operations-type { type enumeration { enum impose-and-forward { description "Operation to impose one or more outgoing labels and forward to the next hop."; } enum pop-and-forward { description "Operation to pop the incoming label and forward to the next hop."; } enum pop-impose-and-forward { description "Operation to pop the incoming label, impose one or more outgoing labels, and forward to the next hop."; } enum swap-and-forward { description "Operation to swap the incoming label with the outgoing label and forward to the next hop."; } enum pop-and-lookup { description "Operation to pop the incoming label and perform a lookup."; } } description "Types of MPLS operations."; } typedef nhlfe-role { type enumeration { enum primary { description "The next hop acts as the primary for carrying traffic."; } enum backup { description "The next hop acts as the backup."; } enum primary-and-backup { description "The next hop simultaneously acts as both the primary and the backup for carrying traffic."; } } description "Role of the next hop."; } grouping nhlfe-single-contents { description "A grouping that describes a single Next Hop Label Forwarding Entry (NHLFE) and its associated parameters as described in the MPLS architecture. This grouping is specific to the case when a single next hop is associated with the route."; uses rt-types:mpls-label-stack; } grouping nhlfe-multiple-contents { description "A grouping that describes a set of NHLFEs and their associated parameters as described in the MPLS architecture. This grouping is used when multiple next hops are associated with the route."; leaf index { type string; description "A user-specified identifier utilized to uniquely reference the next-hop entry in the next-hop list. The value of this index has no semantic meaning other than for referencing the entry."; } leaf backup-index { type string; description "A user-specified identifier utilized to uniquely reference the backup next-hop entry in the NHLFE list. The value of this index has no semantic meaning other than for referencing the entry."; reference "RFC 4090: Fast Reroute Extensions to RSVP-TE for LSP Tunnels RFC 5714: IP Fast Reroute Framework"; } leaf loadshare { type uint16; default "1"; description "This value is used to compute a load share to perform unequal load balancing when multiple outgoing next hops are specified. A share is computed as a ratio of this number to the total under all next hops."; reference "RFC 3031: Multiprotocol Label Switching Architecture, Sections 3.11 and 3.12 RFC 7424: Mechanisms for Optimizing Link Aggregation Group (LAG) and Equal-Cost Multipath (ECMP) Component Link Utilization in Networks, Section 5.4"; } leaf role { type nhlfe-role; description "Role of the NHLFE."; } uses nhlfe-single-contents; } grouping interfaces-mpls { description "List of MPLS interfaces."; container interfaces { description "List of MPLS-enabled interfaces."; list interface { key "name"; description "MPLS-enabled interface entry."; leaf name { type if:interface-ref; description "A reference to the name of an interface in the system that is to be enabled for MPLS."; } leaf mpls-enabled { type boolean; default "false"; description "'true' if MPLS encapsulation is enabled on the interface. 'false' if MPLS encapsulation is disabled on the interface."; } leaf maximum-labeled-packet { type uint32; units "octets"; description "Maximum labeled packet size."; reference "RFC 3032: MPLS Label Stack Encoding, Section 3.2"; } } } } grouping globals { description "MPLS global configuration grouping."; leaf ttl-propagate { type boolean; default "true"; description "Propagate TTL between IP and MPLS."; } } grouping label-blocks { description "Label-block allocation grouping."; container mpls-label-blocks { description "Label-block allocation container."; list mpls-label-block { key "index"; description "List of MPLS label blocks."; leaf index { type string; description "A user-specified identifier utilized to uniquely reference an MPLS label block."; } leaf start-label { type rt-types:mpls-label; must '. <= ../end-label' { error-message "'start-label' must be less than or equal " + "to 'end-label'"; } description "Label-block start."; } leaf end-label { type rt-types:mpls-label; must '. >= ../start-label' { error-message "'end-label' must be greater than or " + "equal to 'start-label'"; } description "Label-block end."; } leaf block-allocation-mode { type identityref { base label-block-alloc-mode; } description "Label-block allocation mode."; } leaf inuse-labels-count { when "derived-from-or-self(../block-allocation-mode, " + "'mpls:label-block-alloc-mode-manager')"; type yang:gauge32; config false; description "Number of labels in use in the label block."; } } } } grouping rib-mpls-properties { description "A grouping of native MPLS RIB properties."; leaf destination-prefix { type leafref { path "../mpls-local-label"; } description "MPLS destination prefix."; } leaf route-context { type string; description "A context associated with the native MPLS route."; } } grouping rib-active-route-mpls-input { description "A grouping applicable to native MPLS RIB 'active-route' RPC input augmentation."; leaf destination-address { type leafref { path "../mpls-local-label"; } description "MPLS native 'active-route' destination."; } leaf mpls-local-label { type rt-types:mpls-label; description "MPLS local label."; } } augment "/rt:routing" { description "MPLS augmentation."; container mpls { description "MPLS container to be used as an augmentation target node for the configuration of other MPLS sub-features, e.g., MPLS static Label Switched Paths (LSPs), MPLS LDP LSPs, and Traffic Engineering MPLS LSP Tunnels."; uses globals; uses label-blocks; uses interfaces-mpls; } } /* Augmentation of MPLS routes */ augment "/rt:routing/rt:ribs/rt:rib/rt:routes/rt:route" { description "This augmentation is applicable to all MPLS routes."; leaf mpls-enabled { type boolean; default "false"; description "Indicates whether MPLS is enabled for this route."; } leaf mpls-local-label { when "../mpls-enabled = 'true'"; type rt-types:mpls-label; description "MPLS local label associated with the route."; } uses rib-mpls-properties { /* MPLS Address Family (AF) augmentation to the native MPLS RIB */ when "derived-from-or-self(../../rt:address-family, " + "'mpls:mpls')" { description "This augment is valid only for routes of the native MPLS RIB."; } } } /* MPLS simple-next-hop augmentation */ augment "/rt:routing/rt:ribs/rt:rib/rt:routes/rt:route/" + "rt:next-hop/rt:next-hop-options/rt:simple-next-hop" { description "Augments the 'simple-next-hop' case in IP unicast routes."; uses nhlfe-single-contents { when "/rt:routing/rt:ribs/rt:rib/rt:routes/rt:route" + "/mpls:mpls-enabled = 'true'"; } } /* MPLS next-hop-list augmentation */ augment "/rt:routing/rt:ribs/rt:rib/rt:routes/rt:route/" + "rt:next-hop/rt:next-hop-options/rt:next-hop-list/" + "rt:next-hop-list/rt:next-hop" { description "This leaf augments the 'next-hop-list' case of IP unicast routes."; uses nhlfe-multiple-contents { when "/rt:routing/rt:ribs/rt:rib/rt:routes/rt:route" + "/mpls:mpls-enabled = 'true'"; } } /* MPLS RPC input augmentation */ augment "/rt:routing/rt:ribs/rt:rib/rt:active-route/rt:input" { description "Input MPLS augmentation for the 'active-route' action statement."; uses rib-active-route-mpls-input { /* MPLS AF augmentation to the native MPLS RIB */ when "derived-from-or-self(../rt:address-family, " + "'mpls:mpls')" { description "This augment is valid only for routes of the native MPLS RIB."; } } } /* MPLS RPC output augmentation */ augment "/rt:routing/rt:ribs/rt:rib/rt:active-route/" + "rt:output/rt:route/" + "rt:next-hop/rt:next-hop-options/rt:simple-next-hop" { description "Output MPLS augmentation for the 'active-route' action statement."; uses nhlfe-single-contents; } augment "/rt:routing/rt:ribs/rt:rib/rt:active-route/" + "rt:output/rt:route/" + "rt:next-hop/rt:next-hop-options/rt:next-hop-list/" + "rt:next-hop-list/rt:next-hop" { description "Output MPLS augmentation for the 'active-route' action statement."; uses nhlfe-multiple-contents; } }

IANA Considerations This document registers the following URI in the "ns" subregistry of the "IETF XML Registry" .

URI:

urn:ietf:params:xml:ns:yang:ietf-mpls

Registrant Contact:

The MPLS WG of the IETF.

XML:

N/A; the requested URI is an XML namespace.

This document registers the following YANG module in the "YANG Module Names" registry .

Name:

ietf-mpls

Namespace:

urn:ietf:params:xml:ns:yang:ietf-mpls

Prefix:

mpls

Reference:

RFC 8960

Security Considerations The YANG module specified in this document defines a schema for data that is designed to be accessed via network management protocols such as NETCONF or RESTCONF . The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) . The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS . The Network Configuration Access Control Model (NACM) 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. 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:

"/rt:routing/mpls:mpls/mpls:label-blocks":

There are data nodes under this path that are writable, such as "start-label" and "end-label". Write operations to those data nodes may result in disruption to existing traffic.

Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes and their sensitivity/vulnerability:

"/rt:routing/rt:ribs/rt:rib/rt:routes/rt:route/rt:next-hop/rt:next-hop-options/rt:next-hop-list/rt:next-hop-list/rt:next-hop" and "/rt:routing/rt:ribs/rt:rib/rt:active-route/rt:output/rt:route/rt:next-hop/rt:next-hop-options/rt:simple-next-hop":

These two paths are augmented by additional MPLS leafs defined in this model. Access to this information may disclose the next-hop information for the prefix route and/or other information.

Some of the RPC operations in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control access to these operations. These are the operations and their sensitivity/vulnerability:

"/rt:routing/rt:ribs/rt:rib/rt:active-route/rt:input" and "/rt:routing/rt:ribs/rt:rib/rt:active-route/rt:output/rt:route":

These two paths are augmented by additional MPLS data nodes that are defined in this model. Access to those paths may disclose information about per-prefix routes and/or other information; such disclosure may be used for further attacks.

The security considerations spelled out in and apply for this document as well.

References Normative References This document specifies the encoding to be used by an LSR in order to transmit labeled packets on Point-to-Point Protocol (PPP) data links, on LAN data links, and possibly on other data links as well. This document also specifies rules and procedures for processing the various fields of the label stack encoding. [STANDARDS-TRACK] This document describes an IANA maintained registry for IETF standards which use Extensible Markup Language (XML) related items such as Namespaces, Document Type Declarations (DTDs), Schemas, and Resource Description Framework (RDF) Schemas. YANG is a data modeling language used to model configuration and state data manipulated by the Network Configuration Protocol (NETCONF), NETCONF remote procedure calls, and NETCONF notifications. [STANDARDS-TRACK] The Network Configuration Protocol (NETCONF) defined in this document provides mechanisms to install, manipulate, and delete the configuration of network devices. It uses an Extensible Markup Language (XML)-based data encoding for the configuration data as well as the protocol messages. The NETCONF protocol operations are realized as remote procedure calls (RPCs). This document obsoletes RFC 4741. [STANDARDS-TRACK] This document describes a method for invoking and running the Network Configuration Protocol (NETCONF) within a Secure Shell (SSH) session as an SSH subsystem. This document obsoletes RFC 4742. [STANDARDS-TRACK] This document introduces a collection of common data types to be used with the YANG data modeling language. This document obsoletes RFC 6021. YANG is a data modeling language used to model configuration data, state data, Remote Procedure Calls, and notifications for network management protocols. This document describes the syntax and semantics of version 1.1 of the YANG language. YANG version 1.1 is a maintenance release of the YANG language, addressing ambiguities and defects in the original specification. There are a small number of backward incompatibilities from YANG version 1. This document also specifies the YANG mappings to the Network Configuration Protocol (NETCONF). This document describes an HTTP-based protocol that provides a programmatic interface for accessing data defined in YANG, using the datastore concepts defined in the Network Configuration Protocol (NETCONF). 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 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. The standardization of network configuration interfaces for use with the Network Configuration Protocol (NETCONF) or the RESTCONF protocol requires a structured and secure operating environment that promotes human usability and multi-vendor interoperability. There is a need for standard mechanisms to restrict NETCONF or RESTCONF protocol access for particular users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. This document defines such an access control model. This document obsoletes RFC 6536. Datastores are a fundamental concept binding the data models written in the YANG data modeling language to network management protocols such as the Network Configuration Protocol (NETCONF) and RESTCONF. This document defines an architectural framework for datastores based on the experience gained with the initial simpler model, addressing requirements that were not well supported in the initial model. This document updates RFC 7950. This document defines a YANG data model for the management of network interfaces. It is expected that interface-type-specific data models augment the generic interfaces data model defined in this document. The data model includes definitions for configuration and system state (status information and counters for the collection of statistics). The YANG data model in this document conforms to the Network Management Datastore Architecture (NMDA) defined in RFC 8342. This document obsoletes RFC 7223. This document specifies three YANG modules and one submodule. Together, they form the core routing data model that serves as a framework for configuring and managing a routing subsystem. It is expected that these modules will be augmented by additional YANG modules defining data models for control-plane protocols, route filters, and other functions. The core routing data model provides common building blocks for such extensions -- routes, Routing Information Bases (RIBs), and control-plane protocols. The YANG modules in this document conform to the Network Management Datastore Architecture (NMDA). This document obsoletes RFC 8022. Segment Routing (SR) leverages the source routing paradigm. A node steers a packet through an ordered list of instructions, called "segments". A segment can represent any instruction, topological or service based. A segment can have a semantic local to an SR node or global within an SR domain. SR provides a mechanism that allows a flow to be restricted to a specific topological path, while maintaining per-flow state only at the ingress node(s) to the SR domain. SR can be directly applied to the MPLS architecture with no change to the forwarding plane. A segment is encoded as an MPLS label. An ordered list of segments is encoded as a stack of labels. The segment to process is on the top of the stack. Upon completion of a segment, the related label is popped from the stack. SR can be applied to the IPv6 architecture, with a new type of routing header. A segment is encoded as an IPv6 address. An ordered list of segments is encoded as an ordered list of IPv6 addresses in the routing header. The active segment is indicated by the Destination Address (DA) of the packet. The next active segment is indicated by a pointer in the new routing header. This document specifies version 1.3 of the Transport Layer Security (TLS) protocol. TLS allows client/server applications to communicate over the Internet in a way that is designed to prevent eavesdropping, tampering, and message forgery. This document updates RFCs 5705 and 6066, and obsoletes RFCs 5077, 5246, and 6961. This document also specifies new requirements for TLS 1.2 implementations. Informative References This document specifies the architecture for Multiprotocol Label Switching (MPLS). [STANDARDS-TRACK] This document defines RSVP-TE extensions to establish backup label-switched path (LSP) tunnels for local repair of LSP tunnels. These mechanisms enable the re-direction of traffic onto backup LSP tunnels in 10s of milliseconds, in the event of a failure. Two methods are defined here. The one-to-one backup method creates detour LSPs for each protected LSP at each potential point of local repair. The facility backup method creates a bypass tunnel to protect a potential failure point; by taking advantage of MPLS label stacking, this bypass tunnel can protect a set of LSPs that have similar backup constraints. Both methods can be used to protect links and nodes during network failure. The described behavior and extensions to RSVP allow nodes to implement either method or both and to interoperate in a mixed network. [STANDARDS-TRACK] This document provides a framework for the development of IP fast- reroute mechanisms that provide protection against link or router failure by invoking locally determined repair paths. Unlike MPLS fast-reroute, the mechanisms are applicable to a network employing conventional IP routing and forwarding. This document is not an Internet Standards Track specification; it is published for informational purposes. Demands on networking infrastructure are growing exponentially due to bandwidth-hungry applications such as rich media applications and inter-data-center communications. In this context, it is important to optimally use the bandwidth in wired networks that extensively use link aggregation groups and equal-cost multipaths as techniques for bandwidth scaling. This document explores some of the mechanisms useful for achieving this. This document defines encoding rules for representing configuration data, state data, parameters of Remote Procedure Call (RPC) operations or actions, and notifications defined using YANG as JavaScript Object Notation (JSON) text.

Data Tree Instance Example A simple network setup is shown in . R1 runs the IS-IS routing protocol and learns about the reachability of two IPv4 prefixes (P1: 198.51.100.1/32 and P2: 198.51.100.2/32) and two IPv6 prefixes (P3: 2001:db8:0:10::1/128 and P4: 2001:db8:0:10::2/128). We also assume that R1 learns about local and remote MPLS label bindings for each prefix using IS-IS (e.g., using Segment Routing (SR) extensions).

Example of Network Configuration State on R1: ============ IPv4 Prefix MPLS Label P1: 198.51.100.1/32 16001 P2: 198.51.100.2/32 16002 IPv6 Prefix MPLS Label P3: 2001:db8:0:10::1/128 16003 P4: 2001:db8:0:10::2/128 16004 RSVP MPLS LSPv4-Tunnel: Source: 198.51.100.3 Destination: 198.51.100.4 Tunnel-ID: 10 LSP-ID: 1 192.0.2.5/30 2001:db8:0:1::1/64 eth0 +--- / +-----+ | R1 | +-----+ \ +--- eth1 192.0.2.13/30 2001:db8:0:2::1/64

The instance data tree could then be illustrated as shown in , using JSON format :

Instance Data Tree Example { "ietf-routing:routing":{ "ribs":{ "rib":[ { "name":"RIB-V4", "address-family": "ietf-ipv4-unicast-routing:v4ur:ipv4-unicast", "routes":{ "route":[ { "next-hop":{ "outgoing-interface":"eth0", "ietf-mpls:mpls-label-stack":{ "entry":[ { "id":1, "label":16001, "ttl":255 } ] }, "ietf-ipv4-unicast-routing:next-hop-address": "192.0.2.5" }, "source-protocol":"ietf-isis:isis", "ietf-mpls:mpls-enabled":true, "ietf-mpls:mpls-local-label":16001, "ietf-ipv4-unicast-routing:destination-prefix": "198.51.100.1/32", "ietf-mpls:route-context":"SID-IDX:1" }, { "next-hop":{ "next-hop-list":{ "next-hop":[ { "outgoing-interface":"eth0", "ietf-mpls:index":"1", "ietf-mpls:backup-index":"2", "ietf-mpls:role":"primary-and-backup", "ietf-mpls:mpls-label-stack":{ "entry":[ { "id":1, "label":16002, "ttl":255 } ] }, "ietf-ipv4-unicast-routing:address": "192.0.2.5" }, { "outgoing-interface":"eth1", "ietf-mpls:index":"2", "ietf-mpls:backup-index":"1", "ietf-mpls:role":"primary-and-backup", "ietf-mpls:mpls-label-stack":{ "entry":[ { "id":1, "label":16002, "ttl":255 } ] }, "ietf-ipv4-unicast-routing:address": "192.0.2.13" } ] } }, "source-protocol":"ietf-isis:isis", "ietf-mpls:mpls-enabled":true, "ietf-mpls:mpls-local-label":16002, "ietf-ipv4-unicast-routing:destination-prefix": "198.51.100.2/32", "ietf-mpls:route-context":"SID-IDX:2" } ] } }, { "name":"RIB-V6", "address-family": "ietf-ipv6-unicast-routing:v6ur:ipv6-unicast", "routes":{ "route":[ { "next-hop":{ "outgoing-interface":"eth0", "ietf-mpls:mpls-label-stack":{ "entry":[ { "id":1, "label":16003, "ttl":255 } ] }, "ietf-ipv6-unicast-routing:next-hop-address": "2001:db8:0:1::1" }, "source-protocol":"ietf-isis:isis", "ietf-mpls:mpls-enabled":true, "ietf-mpls:mpls-local-label":16003, "ietf-ipv6-unicast-routing:destination-prefix": "2001:db8:0:10::1/128", "ietf-mpls:route-context":"SID-IDX:3" }, { "next-hop":{ "next-hop-list":{ "next-hop":[ { "outgoing-interface":"eth0", "ietf-mpls:index":"1", "ietf-mpls:backup-index":"2", "ietf-mpls:role":"primary-and-backup", "ietf-mpls:mpls-label-stack":{ "entry":[ { "id":1, "label":16004, "ttl":255 } ] }, "ietf-ipv6-unicast-routing:address": "2001:db8:0:1::1" }, { "outgoing-interface":"eth1", "ietf-mpls:index":"2", "ietf-mpls:backup-index":"1", "ietf-mpls:role":"primary-and-backup", "ietf-mpls:mpls-label-stack":{ "entry":[ { "id":1, "label":16004, "ttl":255 } ] }, "ietf-ipv6-unicast-routing:address": "2001:db8:0:2::1" } ] } }, "source-protocol":"ietf-isis:isis", "ietf-mpls:mpls-enabled":true, "ietf-mpls:mpls-local-label":16004, "ietf-ipv6-unicast-routing:destination-prefix": "2001:db8:0:10::2/128", "ietf-mpls:route-context":"SID-IDX:4" } ] } }, { "name":"RIB-MPLS", "address-family":"ietf-mpls:mpls:mpls", "routes":{ "route":[ { "next-hop":{ "outgoing-interface":"eth0", "ietf-mpls:mpls-label-stack":{ "entry":[ { "id":1, "label":24002, "ttl":255 } ] }, "ietf-ipv4-unicast-routing:next-hop-address": "192.0.2.5" }, "source-protocol":"ietf-rsvp:rsvp", "ietf-mpls:mpls-enabled":true, "ietf-mpls:mpls-local-label":24001, "ietf-mpls:destination-prefix":"24001", "ietf-mpls:route-context": "RSVP Src:198.51.100.3,Dst:198.51.100.4,T:10,L:1" } ] } } ] }, "ietf-mpls:mpls":{ "mpls-label-blocks":{ "mpls-label-block":[ { "index":"mpls-srgb-label-block", "start-label":16000, "end-label":16500, "block-allocation-mode": "ietf-mpls:label-block-alloc-mode-manager" } ] }, "interfaces":{ "interface":[ { "name":"eth0", "mpls-enabled":true, "maximum-labeled-packet":1488 }, { "name":"eth1", "mpls-enabled":true, "maximum-labeled-packet":1488 } ] } } } }

Acknowledgments The authors would like to thank for her contributions to the early draft revisions of this document.

Contributors Huawei Technologies

i_bryskin@yahoo.com

Ciena

hshah@ciena.com

Authors' Addresses Juniper Networks

tsaad@juniper.net

Cisco Systems, Inc.

skraza@cisco.com

Cisco Systems, Inc.

rgandhi@cisco.com

Volta Networks

xufeng.liu.ietf@gmail.com

Juniper Networks

vbeeram@juniper.net