A YANG Data Model for MPLS BaseJuniper Networkstsaad@juniper.netCisco Systems, Inc.skraza@cisco.comCisco Systems, Inc.rgandhi@cisco.comVolta Networksxufeng.liu.ietf@gmail.comJuniper Networksvbeeram@juniper.netMPLS YANG Data ModelMPLS ModelMPLS RIBMPLS Routing Information BaseThis 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.
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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
IntroductionA 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) .TerminologyThe 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 ModelThis 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 OverviewThis 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 OrganizationThe "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:
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.
The operation to perform on the packet's label stack. This
can be one of the following operations:
Replace the label at the top of the label stack with one or more
specified new labels.
Pop the label stack.
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.
Push one or more labels onto an unlabeled packet.
The NHLFE may also contain:
The data-link encapsulation to use when transmitting the packet.
The way to encode the label stack when transmitting the packet.
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 DesignThe 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.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 DiagramThe MPLS base tree diagram, which follows the notation defined in , is shown in .MPLS Base YANG ModuleThis 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
.IANA ConsiderationsThis 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 ConsiderationsThe 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.ReferencesNormative ReferencesMPLS Label Stack EncodingThis 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]The IETF XML RegistryThis 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 - A Data Modeling Language for the Network Configuration Protocol (NETCONF)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]Network Configuration Protocol (NETCONF)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]Using the NETCONF Protocol over Secure Shell (SSH)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]Common YANG Data TypesThis document introduces a collection of common data types to be used with the YANG data modeling language. This document obsoletes RFC 6021.The YANG 1.1 Data Modeling LanguageYANG 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).RESTCONF ProtocolThis 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).Common YANG Data Types for the Routing AreaThis 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.YANG Tree DiagramsThis 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.Network Configuration Access Control ModelThe 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.Network Management Datastore Architecture (NMDA)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.A YANG Data Model for Interface ManagementThis 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.A YANG Data Model for Routing Management (NMDA Version)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 ArchitectureSegment 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.The Transport Layer Security (TLS) Protocol Version 1.3This 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 ReferencesMultiprotocol Label Switching ArchitectureThis document specifies the architecture for Multiprotocol Label Switching (MPLS). [STANDARDS-TRACK]Fast Reroute Extensions to RSVP-TE for LSP TunnelsThis 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]IP Fast Reroute FrameworkThis 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.Mechanisms for Optimizing Link Aggregation Group (LAG) and Equal-Cost Multipath (ECMP) Component Link Utilization in NetworksDemands 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.JSON Encoding of Data Modeled with YANGThis 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 ExampleA 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).The instance data tree could then be
illustrated as shown in , using JSON format :AcknowledgmentsThe authors would like to thank for
her contributions to the early draft revisions of this document.ContributorsHuawei Technologiesi_bryskin@yahoo.comCienahshah@ciena.comAuthors' AddressesJuniper Networkstsaad@juniper.netCisco Systems, Inc.skraza@cisco.comCisco Systems, Inc.rgandhi@cisco.comVolta Networksxufeng.liu.ietf@gmail.comJuniper Networksvbeeram@juniper.net