RFC 8960
A YANG Data Model for MPLS Base
RFC 8960: A YANG Data Model for MPLS Base 💖
Okay bestie, this one is the spec for the MPLS base YANG data model 🎀. It's the foundation that other MPLS YANG models build on top of. Let's get into it ✨
Here's the title block info. It's an Internet Engineering Task Force (IETF) document, published in December 2020. The category is Standards Track and the ISSN is 2070-1721 🦋. The authors are T. Saad (Juniper Networks), K. Raza, R. Gandhi (Cisco Systems, Inc.), X. Liu (Volta Networks), and V. Beeram (Juniper Networks) 🫶. The title block doesn't list anything this document obsoletes or updates, so no drama there 🙈.
Abstract ✨
Okay so this document specifies the MPLS base YANG data model 💅. It's a base framework for configuring and managing an MPLS switching subsystem on an MPLS-enabled router. Other MPLS YANG data models, like the MPLS Label Switched Path (LSP) static, LDP, or RSVP-TE ones, are expected to augment it 🌸.
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 https://www.rfc-editor.org/info/rfc8960.
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 (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
1.1. Terminology
1.2. Acronyms and Abbreviations
2. MPLS Base Model
2.1. Model Overview
2.2. Model Organization
2.3. Model Design
2.4. Model Tree Diagram
2.5. MPLS Base YANG Module
3. IANA Considerations
4. Security Considerations
5. References
5.1. Normative References
5.2. Informative References
Appendix A. Data Tree Instance Example
Acknowledgments
Contributors
Authors' Addresses1. Introduction 🧚
A core routing YANG data model is defined in [RFC8349]. It gives you a basis for building routing data models for specific Address Families (AFs) 🌷. Specifically, [RFC8349] defines a model for a generic Routing Information Base (RIB) that is AF agnostic. [RFC8349] also defines two RIB instances based on that generic model, one for IPv4 and one for IPv6 AFs.
The MPLS base model in this document augments the generic RIB model from [RFC8349] with extra data. That data enables MPLS forwarding for one or more specific destination prefixes that live in one or more AF RIBs, as described in the MPLS architecture document [RFC3031] 💖.
The MPLS base model also defines a brand new instance of the generic RIB YANG data model from [RFC8349], used to store native MPLS routes 🦋. The native MPLS RIB instance holds one or more routes that aren't tied to other AF instance RIBs (like IPv4 or IPv6 instance RIBs) but are still enabled for MPLS forwarding. Examples 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 [RFC8402] 🌈.
The MPLS base YANG data model is the basis for future MPLS YANG data models covering more sophisticated MPLS features and subsystems ✨. The main purpose is to provide essential building blocks for other YANG data models involving different control-plane protocols and MPLS functions 👑.
So the plan is for the MPLS base data model to get augmented by a bunch of other YANG modules developed by the IETF, for example by the TEAS and MPLS Working Groups 🫶.
The YANG module defined in this document conforms to the Network Management Datastore Architecture (NMDA) [RFC8342] 💅.
1.1. Terminology
The terminology for describing YANG data models is found in [RFC7950] 📚.
1.2. 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
2. MPLS Base Model 🎀
This document describes the "ietf-mpls" YANG module, which provides the base components of the MPLS data model 💜. It's expected that other MPLS YANG modules will augment the "ietf-mpls" YANG module for other MPLS extensions that provision LSPs (for example MPLS static, MPLS LDP, or MPLS RSVP-TE LSPs) 🌸.
2.1. Model Overview
This document models MPLS-labeled routes as an augmentation of the generic routing RIB data model defined in [RFC8349]. For example, IP prefix routes (like routes stored in IPv4 or IPv6 RIBs) get augmented with extra data so they can be used for MPLS forwarding 🦋.
This document also defines a new instance of the generic RIB model from [RFC8349] to store one or more native MPLS routes (more on those in Section 2.3). It does this by extending the identity "address-family" defined in [RFC8349] with a new "mpls" identity. See Section 3 of [RFC8349] for that ✨.
2.2. Model Organization
Here's the relationship between the modules, the way the figure shows it 🍓:
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 onlyFigure 1: Relationship between MPLS Modules 🌈
The "ietf-mpls" YANG module defines the following identities 💅:
mpls: Identity that extends the "address-family" identity of RIB instances, as defined in [RFC8349], 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 [RFC3031]. 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:
- a. Replace the label at the top of the label stack with one or more specified new labels.
- b. Pop the label stack.
- c. 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.
- d. 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.
More groupings in the "ietf-mpls" module 💖:
nhlfe-multiple-contents: A YANG grouping that describes a set of NHLFEs and their associated parameters as described in the MPLS architecture document [RFC3031]. 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 [RFC3031].rib-active-route-mpls-input: A YANG grouping for the augmentation to the "active-route" RPC that is specific to the MPLS RIB instance. 🌸
2.3. Model Design ✨
okay so the MPLS routing model is built on top of the core routing data model in [RFC8349], which is the foundation everything else here stands on 🫶 Figure 2 shows what the MPLS base model adds to the RIBs it touches.
+-----------------+
| 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
Figure 2: Relationship between MPLS Model and RIB Instancesso as you can see in Figure 2, the MPLS base YANG data model augments the existing AF RIB instances 💅 with extra data that lets MPLS forwarding work for the destination prefixes living in those RIBs. for example, an IPv4 prefix in RIB(v4) gets glowed up with an MPLS local label and one or more per-next-hop remote labels, so it can be forwarded with MPLS 🦋
the MPLS base model also creates its own separate instance of the generic RIB model from [RFC8349] 🌈 this one stores MPLS native routes. these are routes that are enabled for MPLS forwarding but aren't stored in any other AF RIB.
some examples of these native MPLS routes:
- 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 [RFC8402].
2.4. Model Tree Diagram 🌸
the MPLS base tree diagram is next 🧚 it follows the notation defined in [RFC8340], and you can see it in Figure 3. it's giving very organized ngl 💜
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
Figure 3: MPLS Base Tree Diagram2.5. MPLS Base YANG Module 💖
this section is where we meet the "ietf-mpls" YANG module 🎀 it gives you the base pieces of the MPLS data model, and other YANG modules can import and augment it to add their own feature-specific data. main character energy for sure ✨
the "ietf-mpls" module imports these YANG modules:
"ietf-routing"as defined in [RFC8349]"ietf-routing-types"as defined in [RFC8294]"ietf-yang-types"as defined in [RFC6991]"ietf-interfaces"as defined in [RFC8343]
the module also references these RFCs while it defines its types, YANG groupings, and other features: [RFC3031], [RFC3032], [RFC4090], [RFC5714], and [RFC7424] 📚
here's the full module, verbatim, bestie 🫶 (don't touch a single character, implementers rely on every bit of this 😭)
<CODE BEGINS> file "ietf-mpls@2020-12-18.yang"
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;
}Okay bestie, the YANG module keeps going and it is SO good 🎀 Here's the rest, every line, no cuts 💅
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;
}
}
<CODE ENDS>Figure 4: MPLS Base YANG Module 🌈
3. IANA Considerations 🦋
Okay so IANA gets a little homework here 📝 We're registering a brand new URI in the "ns" subregistry of the "IETF XML Registry" [RFC3688] 💜
- 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.
And we also register the YANG module in the "YANG Module Names" registry [RFC6020] 🧚♀️
- Name:
ietf-mpls - Namespace:
urn:ietf:params:xml:ns:yang:ietf-mpls - Prefix:
mpls - Reference:
RFC 8960
4. Security Considerations 🔐
Okay bestie, security time, and it's serious 😭 This YANG module defines a schema for data that's meant to be reached through network management protocols like NETCONF [RFC6241] or RESTCONF [RFC8040]. For NETCONF, the lowest layer is the secure transport layer, and the one every implementation has to support is Secure Shell (SSH) [RFC6242]. For RESTCONF, the lowest layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446]. 🔒✨
The Network Configuration Access Control Model (NACM) [RFC8341] is the bouncer here 💅 It lets you restrict particular NETCONF or RESTCONF users to a preset subset of protocol operations and content. Iconic gatekeeping energy.
Now the spicy part. A bunch of the data nodes in this module are writable, creatable, and deletable (that's config true, which is the default) 🚨 These nodes might be sensitive or vulnerable depending on the network. If someone writes to them (like with edit-config) without proper protection, it can really mess with network operations. Here are the subtrees and why they're sensitive:
"/rt:routing/mpls:mpls/mpls:label-blocks":- There are writable nodes under this path, like
"start-label"and"end-label". Writing to those can disrupt existing traffic. Not me panicking 💀
- There are writable nodes under this path, like
Some of the readable data nodes in this module might also be sensitive or vulnerable in some environments, so it's important to control read access to them (via get, get-config, or notification). Here's the list:
"/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 get augmented with extra MPLS leafs defined in this model. Access to them can reveal next-hop information for the prefix route, and maybe other info too 👀
Some RPC operations in this module might be sensitive or vulnerable too, so controlling access to them matters just as much 🔥 Here are the operations:
"/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 with extra MPLS data nodes from this model. Access to them can disclose info about per-prefix routes and other stuff, and that disclosure can be used for further attacks. Literally a red flag 🚩
Also, the security considerations in [RFC3031] and [RFC3032] apply to this document too 🫶
5. References 📚
5.1. Normative References
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001, https://www.rfc-editor.org/info/rfc3032.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, https://www.rfc-editor.org/info/rfc3688.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010, https://www.rfc-editor.org/info/rfc6020.
[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, https://www.rfc-editor.org/info/rfc6241.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, https://www.rfc-editor.org/info/rfc6242.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, https://www.rfc-editor.org/info/rfc6991.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, https://www.rfc-editor.org/info/rfc7950.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, https://www.rfc-editor.org/info/rfc8040.
[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, https://www.rfc-editor.org/info/rfc8294.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, https://www.rfc-editor.org/info/rfc8340.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, March 2018, https://www.rfc-editor.org/info/rfc8341.
[RFC8342] Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K., and R. Wilton, "Network Management Datastore Architecture (NMDA)", RFC 8342, DOI 10.17487/RFC8342, March 2018, https://www.rfc-editor.org/info/rfc8342.
[RFC8343] Bjorklund, M., "A YANG Data Model for Interface Management", RFC 8343, DOI 10.17487/RFC8343, March 2018, https://www.rfc-editor.org/info/rfc8343.
[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, https://www.rfc-editor.org/info/rfc8349.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., Decraene, B., Litkowski, S., and R. Shakir, "Segment Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, July 2018, https://www.rfc-editor.org/info/rfc8402.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, https://www.rfc-editor.org/info/rfc8446.
5.2. Informative References
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol Label Switching Architecture", RFC 3031, DOI 10.17487/RFC3031, January 2001, https://www.rfc-editor.org/info/rfc3031.
[RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, DOI 10.17487/RFC4090, May 2005, https://www.rfc-editor.org/info/rfc4090.
[RFC5714] Shand, M. and S. Bryant, "IP Fast Reroute Framework", RFC 5714, DOI 10.17487/RFC5714, January 2010, https://www.rfc-editor.org/info/rfc5714.
[RFC7424] Krishnan, R., Yong, L., Ghanwani, A., So, N., and B. Khasnabish, "Mechanisms for Optimizing Link Aggregation Group (LAG) and Equal-Cost Multipath (ECMP) Component Link Utilization in Networks", RFC 7424, DOI 10.17487/RFC7424, January 2015, https://www.rfc-editor.org/info/rfc7424.
[RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", RFC 7951, DOI 10.17487/RFC7951, August 2016, https://www.rfc-editor.org/info/rfc7951.
Okay so bestie, we're in the home stretch, and this part is the appendix where the whole model finally comes alive with a real example. 🎀✨
Appendix A. Data Tree Instance Example
A simple network setup is shown in Figure 5. 🌸 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). 💅 So R1 is basically the main character here, and it's learning all the label stuff through IS-IS. Iconic.
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 16004Okay, and here's the RSVP tunnel, which is giving "I have my own plans" energy 🦋
RSVP MPLS LSPv4-Tunnel:
Source: 198.51.100.3
Destination: 198.51.100.4
Tunnel-ID: 10
LSP-ID: 1Here's the topology. R1 sits in the middle with two interfaces, eth0 and eth1, so it has two ways out. 🧚
192.0.2.5/30
2001:db8:0:1::1/64
eth0
+---
/
+-----+
| R1 |
+-----+
\
+---
eth1
192.0.2.13/30
2001:db8:0:2::1/64Figure 5: Example of Network Configuration
The instance data tree could then be illustrated as shown in Figure 6, using JSON format [RFC7951]: 🍓
{
"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
}
]
}
}
}
}Figure 6: Instance Data Tree Example
Acknowledgments
The authors would like to thank Xia Chen for her contributions to the early draft revisions of this document. 🫶 Huge shoutout to Xia, who helped with the early drafts, periodt.
Contributors
Igor Bryskin Huawei Technologies
Email: i_bryskin@yahoo.com
Himanshu Shah Ciena
Email: hshah@ciena.com
Authors' Addresses
Tarek Saad Juniper Networks
Email: tsaad@juniper.net
Kamran Raza Cisco Systems, Inc.
Email: skraza@cisco.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
And that's the whole thing, bestie! 🌈 You now know how a YANG-modelled MPLS base config shows up as real data, and honestly that's so iconic of you for sticking with it. 👑💜
📦 where this page comes from
- ietf: rfc8960 2020-12
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms