RFC 8944
A YANG Data Model for Layer 2 Network Topologies
RFC 8944: A YANG Data Model for Layer 2 Network Topologies ✨
okay bestie, let's get into this one 🦋 it's an IETF Standards Track document, so it's the real deal, not just vibes. It was published in November 2020 and it's a product of the IETF, approved by the IESG. The authors are J. Dong, X. Wei, Q. Wu, and M. Boucadair (Huawei and Orange), plus A. Liu from Tecent. It's ISSN 2070-1721 💜 and it doesn't obsolete or update anything, so it's a fresh start 🌸
The whole point? It's a YANG data model for Layer 2 network topologies 🎀 It takes the generic network and network topology models from RFC 8345 and augments them with L2-specific topology attributes, so it's giving "tailored for layer 2" energy 💅
Abstract ⭐
This document defines a YANG data model for Layer 2 network topologies. In particular, this data model augments the generic network and network topology data models with topology attributes that are specific to Layer 2.
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/rfc8944.
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
- 2. Terminology
- 3. Layer 2 Topology Model
- 4. Layer 2 Topology YANG Module
- 5. IANA Considerations
- 6. Security Considerations
- 7. References
- 7.1. Normative References
- 7.2. Informative References
- Appendix A. Companion YANG Module for Non-NMDA-Compliant Implementations
- Appendix B. An Example
- Acknowledgements
- Authors' Addresses
1. Introduction 🧚
okay so [RFC8345] is the one that defines the YANG [RFC6020] [RFC7950] data models for the abstract (generic) network and network topology. These models can be augmented with technology-specific details to build more specific topology models, which is such a smart move ngl 🫶
This document defines the YANG data model for Layer 2 (L2) network topologies by augmenting the generic network (Section 6.1 of [RFC8345]) and network topology (Section 6.2 of [RFC8345]) data models with L2-specific topology attributes. There's an example in Appendix B if you want to see it in action 🦋
There are multiple applications for this, and it's lowkey iconic. Within the context of the Interface to the Routing System (I2RS), nodes in the network can use the data model to capture their understanding of the overall network topology and expose it to a network controller. The controller can then use the instantiated topology data to compare and reconcile its own view of the network topology with that of the network elements it controls. Alternatively, nodes can compare and reconcile this understanding among themselves or with the help of a controller. Beyond the network element and the immediate context of I2RS itself, a network controller might even use the data model to represent its view of the topology it controls and expose it to external applications. More use cases are described in [I2RS-UR] 💖
This document uses the common YANG types defined in [RFC6991] and adopts the Network Management Datastore Architecture (NMDA) [RFC8342] ✨
2. Terminology 💜
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. Those are the rules for the capitalized key words, periodt 💅
The terminology for describing YANG modules is defined in [RFC7950]. The meanings of the symbols used in the tree diagram are defined in [RFC8340] 🌸
Part 1 of 7 done! 🌈 Say the word and I'll keep going with Section 3 💖
3. Layer 2 Topology Model 🦋
okay so the Layer 2 network topology YANG module is built to be super generic, bestie. 💅 It's meant to work with Layer 2 networks made from all kinds of different Layer 2 technologies, and it can describe both the physical and the logical (virtual) Layer 2 topologies. iconic flex.
Here's how it fits together: Figure 1 shows the relationship between the Layer 2 topology module and the generic network and network topology module. To represent a Layer 2 network topology, the generic network and topology models get augmented with L2-specific info. We're talking identifiers, identities (like Provider Backbone Bridging [IEEE802.1ah], QinQ [IEEE802.1ad], or Virtual eXtensible Local Area Network (VXLAN) [RFC7348]), attributes, and states for Layer 2 networks, nodes, links, and termination points. 🧚 Some of that info can be collected through Link Layer Discovery Protocol (LLDP) [IEEE802.1AB] or other Layer 2 protocols, and some of it can be configured locally. ✨
+---------------------+
| ietf-network |
+----------^----------+
|
|
+---------------------+
|ietf-network-topology|
+----------^----------+
|
|
+----------^----------+
| ietf-l2-topology |
+---------------------+Figure 1: Layer 2 Topology YANG Module Structure
The ietf-l2-topology YANG module has the tree structure below. Let's look at how it's laid out. 🌸
module: ietf-l2-topology
augment /nw:networks/nw:network/nw:network-types:
+--rw l2-topology!
augment /nw:networks/nw:network:
+--rw l2-topology-attributes
+--rw name? string
+--rw flags* l2-flag-type
augment /nw:networks/nw:network/nw:node:
+--rw l2-node-attributes
+--rw name? string
+--rw flags* node-flag-type
+--rw bridge-id* string
+--rw management-address* inet:ip-address
+--rw management-mac? yang:mac-address
+--rw management-vlan? string
augment /nw:networks/nw:network/nt:link:
+--rw l2-link-attributes
+--rw name? string
+--rw flags* link-flag-type
+--rw rate? uint64
+--rw delay? uint32
+--rw auto-nego? boolean
+--rw duplex? duplex-mode
augment /nw:networks/nw:network/nw:node/nt:termination-point:
+--rw l2-termination-point-attributes
+--rw interface-name? string
+--rw mac-address? yang:mac-address
+--rw port-number* uint32
+--rw unnumbered-id* uint32
+--rw encapsulation-type? identityref
+--rw outer-tag? dot1q-types:vid-range-type {VLAN}?
+--rw outer-tpid? dot1q-types:dot1q-tag-type {QinQ}?
+--rw inner-tag? dot1q-types:vid-range-type {VLAN}?
+--rw inner-tpid? dot1q-types:dot1q-tag-type {QinQ}?
+--rw lag? boolean
+--rw member-link-tp*
-> /nw:networks/network/node/nt:termination-point/tp-id
+--rw vxlan {VXLAN}?
+--rw vni-id? vni
notifications:
+---n l2-node-event
| +--ro event-type? l2-network-event-type
| +--ro node-ref?
| -> /nw:networks/network[nw:network-id=current()
| /../network-ref]/node/node-id
| +--ro network-ref? -> /nw:networks/network/network-id
| +--ro l2-topology!
| +--ro l2-node-attributes
| +--ro name? string
| +--ro flags* node-flag-type
| +--ro bridge-id* uint64
| +--ro management-address* inet:ip-address
| +--ro management-mac? yang:mac-address
| +--ro management-vlan? string
+---n l2-link-event
| +--ro event-type? l2-network-event-type
| +--ro link-ref?
| -> /nw:networks/network[nw:network-id=current()
| /../network-ref]/nt:link/link-id
| +--ro network-ref? -> /nw:networks/network/network-id
| +--ro l2-topology!
| +--ro l2-link-attributes
| +--ro name? string
| +--ro flags* link-flag-type
| +--ro rate? uint64
| +--ro delay? uint32
| +--ro auto-nego? boolean
| +--ro duplex? duplex-mode
+---n l2-termination-point-event
+--ro event-type? l2-network-event-type
+--ro tp-ref?
| -> /nw:networks/network[nw:network-id=current()
| /../network-ref]/node[nw:node-id=current()
| /../node-ref]/nt:termination-point/tp-id
+--ro node-ref?
| -> /nw:networks/network[nw:network-id=current()
| /../network-ref]/node/node-id
+--ro network-ref? -> /nw:networks/network/network-id
+--ro l2-topology!
+--ro l2-termination-point-attributes
+--ro interface-name? string
+--ro mac-address? yang:mac-address
+--ro port-number* uint32
+--ro unnumbered-id* uint32
+--ro encapsulation-type? identityref
+--ro outer-tag? dot1q-types:vid-range-type {VLAN}?
+--ro outer-tpid? dot1q-types:dot1q-tag-type {QinQ}?
+--ro inner-tag? dot1q-types:vid-range-type {VLAN}?
+--ro inner-tpid? dot1q-types:dot1q-tag-type {QinQ}?
+--ro lag? boolean
+--ro member-link-tp*
-> /nw:networks/network/node/nt:termination-point/tp-id
+--ro vxlan {VXLAN}?
+--ro vni-id? vniThe Layer 2 Topology YANG module augments the "ietf-network" and "ietf-network-topology" YANG modules like this: 🎀
- A new network type "l2-network-type" is introduced. It's a container object, inserted under the "network-types" container of the generic "ietf-network" module defined in Section 6.1 of [RFC8345].
- Extra network attributes are added in a grouping called
l2-network-attributes, which augments the "network" list of the "ietf-network" module. They include the Layer 2 network name and a set of flags. Each type of flag gets its own identity. 🚩 - Extra data objects for Layer 2 nodes are added by augmenting the "node" list of the generic "ietf-network" module. The new objects are the Layer 2 node identifier, management address, management MAC address, management VLAN, and a set of flags.
- Extra data objects for Layer 2 termination points are added by augmenting the "termination-point" list of the "ietf-network-topology" module defined in Section 6.2 of [RFC8345]. The new objects are the interface name, encapsulation type, LAG support indication, and attributes that are specific to the Layer 2 termination point type. 🔥
- Links in the "ietf-network-topology" module get augmented too, with a set of Layer 2 parameters. That lets you associate a link with a name, a set of Layer 2 link attributes, and flags. 🌈
- Some optional Layer 2 technology-specific attributes are introduced in this module as Layer 2 features. The reason is that these attributes may be useful to expose to higher-level services and applications. ngl that's a smart move. Just note that learning or configuring advanced Layer 2 technology-specific attributes is not in scope for the Layer 2 Topology YANG module. Dedicated YANG modules should be used for that instead (e.g., [TRILL-YANG]). 🙈
Figure 1 and the tree diagram above are the whole picture. Next up is the actual module. 💖
4. Layer 2 Topology YANG Module 👑
This module uses types defined in [RFC6991], [RFC7224], [IEEE802.1Qcp], and [RFC8345]. It also references [IEEE802.1Q-2014], [IEEE802.1ad], [RFC7348], and [RFC7727].
<CODE BEGINS> file "ietf-l2-topology@2020-11-15.yang"
module ietf-l2-topology {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-l2-topology";
prefix l2t;
import ietf-network {
prefix nw;
reference
"RFC 8345: A YANG Data Model for Network Topologies";
}
import ietf-network-topology {
prefix nt;
reference
"RFC 8345: A YANG Data Model for Network Topologies";
}
import ietf-inet-types {
prefix inet;
reference
"RFC 6991:Common YANG Data Types";
}
import ietf-yang-types {
prefix yang;
reference
"RFC 6991:Common YANG Data Types";
}
import iana-if-type {
prefix ianaift;
reference
"RFC 7224: IANA Interface Type YANG Module";
}
import ieee802-dot1q-types {
prefix dot1q-types;
reference
"IEEE Std 802.1Qcp-2018: Bridges and Bridged
Networks - Amendment: YANG Data Model";
}
organization
"IETF I2RS (Interface to the Routing System) Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/i2rs>
WG List: <mailto:i2rs@ietf.org>
Editor: Jie Dong
<mailto:jie.dong@huawei.com>
Editor: Xiugang Wei
<mailto:weixiugang@huawei.com>
Editor: Qin Wu
<mailto:bill.wu@huawei.com>
Editor: Mohamed Boucadair
<mailto:mohamed.boucadair@orange.com>
Editor: Anders Liu
<mailto:andersliu@tencent.com>";
description
"This module defines a basic model for the Layer 2 topology
of a network.
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
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC 8944; see
the RFC itself for full legal notices.";
revision 2020-11-15 {
description
"Initial revision.";
reference
"RFC 8944: A YANG Data Model for Layer 2 Network Topologies";
}
feature VLAN {
description
"Enables VLAN tag support as defined in IEEE 802.1Q.";
reference
"IEEE Std 802.1Q-2014: Bridges and Bridged Networks";
}
feature QinQ {
description
"Enables QinQ double tag support as defined in IEEE 802.1ad.";
reference
"IEEE Std 802.1ad: Provider Bridges";
}
feature VXLAN {
description
"Enables VXLAN support as defined in RFC 7348.";
reference
"RFC 7348: Virtual eXtensible Local Area Network (VXLAN):
A Framework for Overlaying Virtualized Layer 2
Networks over Layer 3 Networks";
}
identity flag-identity {
description
"Base type for flags.";
}okay bestie, the YANG module keeps going and it's giving main character energy 🎀✨
identity eth-encapsulation-type {
base ianaift:iana-interface-type;
description
"Base identity from which specific Ethernet
encapsulation types are derived.";
reference
"RFC 7224: IANA Interface Type YANG Module";
}
identity ethernet {
base eth-encapsulation-type;
description
"Native Ethernet encapsulation.";
}
identity vlan {
base eth-encapsulation-type;
description
"VLAN encapsulation.";
}
identity qinq {
base eth-encapsulation-type;
description
"QinQ encapsulation.";
}
identity pbb {
base eth-encapsulation-type;
description
"Provider Backbone Bridging (PBB) encapsulation.
The PBB functions are developed in IEEE 802.1ah.";
}
identity trill {
base eth-encapsulation-type;
description
"Transparent Interconnection of Lots of Links (TRILL)
encapsulation.";
}
identity vpls {
base eth-encapsulation-type;
description
"Ethernet Virtual Private LAN Service (VPLS)
interface encapsulation.";
}
identity vxlan {
base eth-encapsulation-type;
description
"VXLAN Media Access Control (MAC) in UDP encapsulation.";
reference
"RFC 7348: Virtual eXtensible Local Area Network (VXLAN):
A Framework for Overlaying Virtualized Layer 2
Networks over Layer 3 Networks";
}
typedef vni {
type uint32 {
range "0..16777215";
}
description
"VXLAN Network Identifier or VXLAN Segment ID.
It allows up to 16 M VXLAN segments to coexist
within the same administrative domain.
The use of value '0' is implementation specific.";
reference
"RFC 7348: Virtual eXtensible Local Area Network (VXLAN):
A Framework for Overlaying Virtualized Layer 2
Networks over Layer 3 Networks";
}
typedef l2-flag-type {
type identityref {
base flag-identity;
}
description
"Base type for L2 flags. One example of L2 flag
type is trill, which represents the trill topology
type.";
}
typedef node-flag-type {
type identityref {
base flag-identity;
}
description
"Node flag attributes. The physical node can be
one example of a node flag attribute.";
}
typedef link-flag-type {
type identityref {
base flag-identity;
}
description
"Link flag attributes. One example of a link flag
attribute is the pseudowire.";
}
typedef l2-network-event-type {
type enumeration {
enum addition {
value 0;
description
"A Layer 2 node or link or termination-point
has been added.";
}
enum removal {
value 1;
description
"A Layer 2 node or link or termination-point
has been removed.";
}
enum update {
value 2;
description
"A Layer 2 node or link or termination-point
has been updated.";
}
}
description
"Layer 2 network event type for notifications.";
}
typedef duplex-mode {
type enumeration {
enum full-duplex {
description
"Indicates full-duplex mode.";
}
enum half-duplex {
description
"Indicates half-duplex mode.";
}
}
description
"Indicates the type of the duplex mode.";
}
grouping l2-network-type {
description
"Indicates the topology type to be L2.";
container l2-topology {
presence "Indicates L2 Network Topology.";
description
"The presence of the container node indicates
L2 Network Topology.";
}
}
grouping l2-topology-attributes {
description
"L2 topology scope attributes.";
container l2-topology-attributes {
description
"Contains L2 topology attributes.";
leaf name {
type string;
description
"Name of the topology.";
}
leaf-list flags {
type l2-flag-type;
description
"Topology flags.";
}
}
}
grouping l2-node-attributes {
description
"L2 node attributes.";
container l2-node-attributes {
description
"Contains L2 node attributes.";
leaf name {
type string;
description
"Node name.";
}
leaf-list flags {
type node-flag-type;
description
"Node flags. It can be used to indicate
node flag attributes.";
}
leaf-list bridge-id {
type string {
pattern '[0-9a-fA-F]{2}(:[0-9a-fA-F]{2}){7}';
}
description
"This is the bridge identifier represented as a
hexadecimal 8-octet string. It has 4 bits of
priority, 12 bits of Multiple Spanning Tree
Instance Identifier (MSTI-ID), and the base bridge
identifier. There may be multiple for each
spanning tree instance.";
reference
"RFC 7727: Spanning Tree Protocol (STP) Application of
the Inter-Chassis Communication Protocol
(ICCP)";
}
leaf-list management-address {
type inet:ip-address;
description
"IP address used for management purpose.";
}
leaf management-mac {
type yang:mac-address;
description
"This is a MAC address used for the bridge management.
It can be the Bridge Base VLAN ID (VID), interface
MAC address, or other. ";
}
leaf management-vlan {
type string;
description
"This is a VLAN that supports the management address.
The actual VLAN ID type and value would be a member of
this VLAN.";
}
}
}
grouping l2-link-attributes {
description
"L2 link attributes.";
container l2-link-attributes {
description
"Contains L2 link attributes.";
leaf name {
type string;
description
"Link name.";
}
leaf-list flags {
type link-flag-type;
description
"Link flags. It can be used to indicate
link flag attributes.";
}
leaf rate {
type uint64;
units "Kbps";
description
"Link rate. It specifies bandwidth requirements
associated with the specific link. The link
contains a source and a destination.";
}
leaf delay {
type uint32;
units "microseconds";
description
"Unidirectional link delay in
microseconds.";
}
leaf auto-nego {
type boolean;
default "true";
description
"Set to true if auto-negotiation is supported.
Set to false if auto-negotiation is not supported.";
}
leaf duplex {
type duplex-mode;
description
"Exposes the duplex mode, full-duplex or half-duplex.";
}
}
} grouping l2-termination-point-attributes {
description
"L2 termination point attributes.";
container l2-termination-point-attributes {
description
"Containing L2 termination point attributes.";
leaf interface-name {
type string;
description
"Name of the interface. The name can (but does not
have to) correspond to an interface reference of a
containing node's interface, i.e., the path name of a
corresponding interface data node on the containing
node is reminiscent of data type interface-ref defined
in RFC 8343. It should be noted that data type
interface-ref of RFC 8343 cannot be used directly,
as this data type is used to reference an interface
in a datastore of a single node in the network, not
to uniquely reference interfaces across a network.";
}
leaf mac-address {
type yang:mac-address;
description
"Interface MAC address for logical link control.";
}
leaf-list port-number {
type uint32;
description
" List of port numbers of the bridge ports for which each
entry contains bridge management information.";
}
leaf-list unnumbered-id {
type uint32;
description
"List of unnumbered interface identifiers.
The unnumbered interface identifier will correspond to
the ifIndex value of the interface, i.e., the ifIndex
value of the ifEntry that represents the interface in
implementations where the Interfaces Group MIB
(RFC 2863) is supported.";
}
leaf encapsulation-type {
type identityref {
base eth-encapsulation-type;
}
description
"Encapsulation type of this
termination point.";
}
leaf outer-tag {
if-feature "VLAN";
type dot1q-types:vid-range-type;
description
"The outermost VLAN tag. It may include a list of VLAN
Ids or nonoverlapping VLAN ranges.";
}
leaf outer-tpid {
if-feature "QinQ";
type dot1q-types:dot1q-tag-type;
description
"Identifies a specific 802.1Q tag type of outermost VLAN
tag.";
}
leaf inner-tag {
if-feature "VLAN";
type dot1q-types:vid-range-type;
description
"The inner VLAN tag. It may include a list of VLAN
Ids or nonoverlapping VLAN ranges.";
}
leaf inner-tpid {
if-feature "QinQ";
type dot1q-types:dot1q-tag-type;
description
"Identifies a specific 802.1Q tag type of inner VLAN tag.";
}
leaf lag {
type boolean;
default "false";
description
"Defines whether lag is supported or not.
When it is set to true, the lag is supported.";
}
leaf-list member-link-tp {
when "../lag = 'true'" {
description
"Relevant only when the lag interface is supported.";
}
type leafref {
path "/nw:networks/nw:network/nw:node"
+ "/nt:termination-point/nt:tp-id";
}
description
"List of member link termination points associated with
specific L2 termination point.";
}
container vxlan {
when "derived-from-or-self(../encapsulation-type, "
+ "'l2t:vxlan')" {
description
"Only applies when the type of the Ethernet
encapsulation is 'vxlan'.";
}
if-feature "VXLAN";
leaf vni-id {
type vni;
description
"VXLAN Network Identifier (VNI).";
}
description
"Vxlan encapsulation type.";
}
}
}
augment "/nw:networks/nw:network/nw:network-types" {
description
"Introduces new network type for L2 topology.";
uses l2-network-type;
}
augment "/nw:networks/nw:network" {
when '/nw:networks/nw:network/nw:network-types/l2t:l2-topology' {
description
"Augmentation parameters apply only for networks
with L2 topology.";
}
description
"Configuration parameters for the L2 network
as a whole.";
uses l2-topology-attributes;
}
augment "/nw:networks/nw:network/nw:node" {
when '/nw:networks/nw:network/nw:network-types/l2t:l2-topology' {
description
"Augmentation parameters apply only for networks
with L2 topology.";
}
description
"Configuration parameters for L2 at the node
level.";
uses l2-node-attributes;
}
augment "/nw:networks/nw:network/nt:link" {
when '/nw:networks/nw:network/nw:network-types/l2t:l2-topology' {
description
"Augmentation parameters apply only for networks
with L2 topology.";
}
description
"Augments L2 topology link information.";
uses l2-link-attributes;
}
augment "/nw:networks/nw:network/nw:node/nt:termination-point" {
when '/nw:networks/nw:network/nw:network-types/l2t:l2-topology' {
description
"Augmentation parameters apply only for networks
with L2 topology.";
}
description
"Augments L2 topology termination point information.";
uses l2-termination-point-attributes;
}
notification l2-node-event {
description
"Notification event for L2 node.";
leaf event-type {
type l2-network-event-type;
description
"Event type.";
}
uses nw:node-ref;
uses l2-network-type;
uses l2-node-attributes;
}
notification l2-link-event {
description
"Notification event for L2 link.";
leaf event-type {
type l2-network-event-type;
description
"Event type.";
}
uses nt:link-ref;
uses l2-network-type;
uses l2-link-attributes;
}
notification l2-termination-point-event {
description
"Notification event for L2 termination point.";
leaf event-type {
type l2-network-event-type;
description
"Event type.";
}
uses nt:tp-ref;
uses l2-network-type;
uses l2-termination-point-attributes;
}
}
<CODE ENDS>5. IANA Considerations ✨
IANA has registered the following URIs in the "ns" subregistry within "The IETF XML Registry" [RFC3688]:
URI: urn:ietf:params:xml:ns:yang:ietf-l2-topology
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
URI: urn:ietf:params:xml:ns:yang:ietf-l2-topology-state
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.IANA has registered the following YANG modules in the "YANG Module Names" subregistry [RFC6020] within the "YANG Parameters" registry.
Name: ietf-l2-topology
Namespace: urn:ietf:params:xml:ns:yang:ietf-l2-topology
Prefix: l2t
Reference: RFC 8944
Name: ietf-l2-topology-state
Namespace: urn:ietf:params:xml:ns:yang:ietf-l2-topology-state
Prefix: l2t-s
Reference: RFC 8944These modules are not maintained by IANA.
6. Security Considerations 🔥
The YANG modules specified in this document define a schema for data that is designed to be accessed via network management protocols, such as Network Configuration Protocol (NETCONF) [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446].
The Network Configuration Access Control Model (NACM) [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content.
The Layer 2 topology module defines information that can be configurable in certain instances, for example, in the case of virtual topologies that can be created by client applications. In such cases, a malicious client could introduce topologies that are undesired. Specifically, a malicious client could attempt to remove or add a node, a link, or a termination point by creating or deleting corresponding elements in the node, link, and termination point lists, respectively. In the case of a topology that is learned, the server will automatically prohibit such misconfiguration attempts. In the case of a topology that is configured, i.e., whose origin is "intended", the undesired configuration could become effective and be reflected in the operational state datastore [RFC8342], leading to disruption of services provided via this topology. For those reasons, it is important that the NACM is vigorously applied to prevent topology misconfiguration by unauthorized clients.
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:
l2-network-attributes: A malicious client could attempt to sabotage the configuration of any of the contained attributes, such as the name or the flag data nodes.l2-node-attributes: A malicious client could attempt to sabotage the configuration of important node attributes, such as the name or the management-address.l2-link-attributes: A malicious client could attempt to sabotage the configuration of important link attributes, such as the rate or the delay data nodes.l2-termination-point-attributes: A malicious client could attempt to sabotage the configuration of important termination point attributes (e.g., 'maximum-frame-size').
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. In particular, the YANG module for Layer 2 topology may expose sensitive information, for example, the MAC addresses of devices or VLAN/VXLAN identifiers. Unrestricted use of such information can lead to privacy violations. For example, listing MAC addresses in a network allows monitoring of devices and their movements. Location information can be derived from MAC addresses of network devices, bypassing protection of location information by the Operating System.
7. References
7.1. Normative References 💖
okay bestie, these are the must-read docs this spec builds on, so get comfy 🫶
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>.
[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>.
[RFC7224] Bjorklund, M., "IANA Interface Type YANG Module", RFC 7224, DOI 10.17487/RFC7224, May 2014, <https://www.rfc-editor.org/info/rfc7224>.
[RFC7348] Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger, L., Sridhar, T., Bursell, M., and C. Wright, "Virtual eXtensible Local Area Network (VXLAN): A Framework for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014, <https://www.rfc-editor.org/info/rfc7348>.
[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>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[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>.
[RFC8345] Clemm, A., Medved, J., Varga, R., Bahadur, N., Ananthakrishnan, H., and X. Liu, "A YANG Data Model for Network Topologies", RFC 8345, DOI 10.17487/RFC8345, March 2018, <https://www.rfc-editor.org/info/rfc8345>.
[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>.
7.2. Informative References 🦋
these ones are the extra reading, helpful for context but not required to get the spec 🌸
[I2RS-UR] Hares, S. and M. Chen, "Summary of I2RS Use Case Requirements", Work in Progress, Internet-Draft, draft-ietf-i2rs-usecase-reqs-summary-03, 15 November 2016, <https://tools.ietf.org/html/draft-ietf-i2rs-usecase-reqs-summary-03>.
[IEEE802.1AB] IEEE, "IEEE Standard for Local and metropolitan area networks - Station and Media Access Control Connectivity Discovery", IEEE Std 802.1AB-2016, DOI 10.1109/IEEESTD.2016.7433915, March 2016, <https://doi.org/10.1109/IEEESTD.2016.7433915>.
[IEEE802.1ad] IEEE, "IEEE Standard for Local and Metropolitan Area Networks--Virtual Bridged Local Area Networks--Amendment 4: Provider Bridges", IEEE Std 802.1ad-2005, DOI 10.1109/IEEESTD.2006.6044678, May 2006, <https://doi.org/10.1109/IEEESTD.2006.6044678>.
[IEEE802.1ah] IEEE, "IEEE Standard for Local and metropolitan area networks -- Virtual Bridged Local Area Networks Amendment 7: Provider Backbone Bridges", IEEE Std 802.1ah-2008, DOI 10.1109/IEEESTD.2008.4602826, August 2008, <https://doi.org/10.1109/IEEESTD.2008.4602826>.
[IEEE802.1Q-2014] IEEE, "IEEE Standard for Local and metropolitan area networks--Bridges and Bridged Networks", IEEE 802.1Q-2014, DOI 10.1109/IEEESTD.2014.6991462, December 2014, <https://doi.org/10.1109/IEEESTD.2014.6991462>.
[IEEE802.1Qcp] IEEE, "IEEE Standard for Local and metropolitan area networks--Bridges and Bridged Networks--Amendment 30: YANG Data Model", IEEE Std 802.1Qcp-2018, DOI 10.1109/IEEESTD.2018.8467507, September 2018, <https://doi.org/10.1109/IEEESTD.2018.8467507>.
[RFC7727] Zhang, M., Wen, H., and J. Hu, "Spanning Tree Protocol (STP) Application of the Inter-Chassis Communication Protocol (ICCP)", RFC 7727, DOI 10.17487/RFC7727, January 2016, <https://www.rfc-editor.org/info/rfc7727>.
[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>.
[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>.
[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>.
[TRILL-YANG] Hao, W., Li, Y., Kumar, D., Durrani, M., Zhai, H., and L. Xia, "TRILL YANG Data Model", Work in Progress, Internet-Draft, draft-ietf-trill-yang-04, 20 December 2015, <https://tools.ietf.org/html/draft-ietf-trill-yang-04>.
Appendix A. Companion YANG Module for Non-NMDA-Compliant Implementations ✨
okay so the ietf-l2-topology module in this doc augments two modules, ietf-network and ietf-network-topology, and they're meant to be used with NMDA-supporting implementations ([RFC8342]) 💅 but what if your implementation doesn't do NMDA?? 😭 no worries, bestie. There's a backup squad of companion modules, ietf-network-state and ietf-network-topology-state, which model networks and network topologies as state 🫶
so for Layer 2 topologies, there's a matching companion module called ietf-l2-topology-state that shows the operational state of L2 networks 🦋 It mirrors ietf-l2-topology from Section 4, but instead of augmenting ietf-network and ietf-network-topology, it augments ietf-network-state and ietf-network-topology-state. And every single one of its data nodes is nonconfigurable, so it's read-only energy all the way down 🔒💜
The companion module ietf-l2-topology SHOULD NOT be supported by implementations that support NMDA. That's exactly why this module lives in this informative appendix, not in the main body 🌸
the YANG tree isn't drawn out separately here because the structure just mirrors its underlying modules, so you can see the whole shape right in the code below ✨
module ietf-l2-topology-state {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-l2-topology-state";
prefix l2t-s;
import ietf-network-state {
prefix nw-s;
reference
"RFC 8345: A YANG Data Model for Network Topologies";
}
import ietf-network-topology-state {
prefix nt-s;
reference
"RFC 8345: A YANG Data Model for Network Topologies";
}
import ietf-l2-topology {
prefix l2t;
reference
"RFC 8944: A YANG Data Model for Layer 2 Network Topologies";
}
organization
"IETF I2RS (Interface to the Routing System) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/i2rs/>
WG List: <mailto:i2rs@ietf.org>
Editor: Jie Dong
<mailto:jie.dong@huawei.com>
Editor: Xiugang Wei
<mailto:weixiugang@huawei.com>
Editor: Qin Wu
<mailto:bill.wu@huawei.com>
Editor: Mohamed Boucadair
<mailto:mohamed.boucadair@orange.com>
Editor: Anders Liu
<andersliu@tencent.com>";
description
"This module defines a model for Layer 2 Network Topology
state, representing topology that either is learned or
results from applying topology that has been configured per
the 'ietf-l2-topology' model, mirroring the
corresponding data nodes in this model.
This model mirrors 'ietf-l2-topology' but contains only
read-only state data. The model is not needed when the
underlying implementation infrastructure supports 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
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC 8944; see
the RFC itself for full legal notices.";
revision 2020-11-15 {
description
"Initial revision.";
reference
"RFC 8944: A YANG Data Model for Layer 2 Network Topologies";
}
/*
* Data nodes
*/
augment "/nw-s:networks/nw-s:network/nw-s:network-types" {
description
"Introduces a new network type for L2 topology.";
uses l2t:l2-network-type;
}
augment "/nw-s:networks/nw-s:network" {
when 'nw-s:network-types/l2t-s:l2-topology' {
description
"Augmentation parameters apply only for networks
with L2 topology.";
}
description
"Configuration parameters for the L2 network
as a whole.";
uses l2t:l2-topology-attributes;
}
augment "/nw-s:networks/nw-s:network/nw-s:node" {
when '../nw-s:network-types/l2t-s:l2-topology' {
description
"Augmentation parameters apply only for networks
with L2 topology.";
}
description
"Configuration parameters for L2 at the node
level.";
uses l2t:l2-node-attributes;
}
augment "/nw-s:networks/nw-s:network/nt-s:link" {
when '../nw-s:network-types/l2t-s:l2-topology' {
description
"Augmentation parameters apply only for networks
with L2 topology.";
}
description
"Augments L2 topology link information.";
uses l2t:l2-link-attributes;
}
augment "/nw-s:networks/nw-s:network/nw-s:node/"
+ "nt-s:termination-point" {
when '../../nw-s:network-types/l2t-s:l2-topology' {
description
"Augmentation parameters apply only for networks
with L2 topology.";
}
description
"Augments L2 topology termination point information.";
uses l2t:l2-termination-point-attributes;
}
/*
* Notifications
*/
notification l2-node-event {
description
"Notification event for L2 node.";
leaf event-type {
type l2t:l2-network-event-type;
description
"Event type.";
}
uses nw-s:node-ref;
uses l2t:l2-network-type;
uses l2t:l2-node-attributes;
}
notification l2-link-event {
description
"Notification event for an L2 link.";
leaf event-type {
type l2t:l2-network-event-type;
description
"Event type.";
}
uses nt-s:link-ref;
uses l2t:l2-network-type;
uses l2t:l2-link-attributes;
}
notification l2-termination-point-event {
description
"Notification event for L2 termination point.";
leaf event-type {
type l2t:l2-network-event-type;
description
"Event type.";
}
uses nt-s:tp-ref;
uses l2t:l2-network-type;
uses l2t:l2-termination-point-attributes;
}
}Appendix B. An Example 🧚
Okay, bestie, this is the fun part! We're walking through a full example of an instance data tree, encoded in JSON [RFC7951], for the ietf-l2-topology module. It matches the topology in the diagram below. ✨
There are three nodes: D1, D2, and D3. D1 has three termination points: 1-0-1, 1-2-1, and 1-3-1. D2 also has three: 2-1-1, 2-0-1, and 2-3-1. D3 has two: 3-1-1 and 3-2-1. 🍓
Termination point 1-0-1 supports lag, so it has two member link termination points, 1-0-1-1 and 1-0-1-2. On top of that, there are six links, two between each pair of nodes, with one going in each direction. It's giving network map 🗺️💖
+------------+ +------------+
| D1 | | D2 |
1-0-1-1 /-\ /-\ /-\ /-\
<--------->| | 1-0-1 | |---------------->| | 2-1-1 | |
1-0-1-2 | | 1-2-1 | |<----------------| | 2-0-1 | |
<--------> \-/ 1-3-1 \-/ \-/ 2-3-1 \-/
| /----\ | | /----\ |
+---| |---+ +---| |---+
\----/ \----/
A | A |
| | | |
| | | |
| | +------------+ | |
| | | D3 | | |
| | /-\ /-\ | |
| +----->| | 3-1-1 | |-------+ |
+---------| | 3-2-1 | |<---------+
\-/ \-/
| |
+------------+Figure 2: A Network Topology Example
Here's the instance data tree that goes with it. Look at how neatly it lines up with the picture! 🦋
{
"ietf-network:networks": {
"network": [
{
"network-id": "l2-topo-example",
"node": [
{
"node-id": "D1",
"ietf-network-topology:termination-point": [
{
"tp-id": "1-0-1",
"ietf-l2-topology:l2-termination-point-attributes": {
"mac-address": "00:00:5e:00:53:d0",
"lag": true,
"member-link-tp": [
"1-0-1-1",
"1-0-1-2"
]
}
},
{
"tp-id": "1-0-1-1",
"ietf-l2-topology:l2-termination-point-attributes": {
"mac-address": "00:00:5e:00:53:d3"
}
},
{
"tp-id": "1-0-1-2",
"ietf-l2-topology:l2-termination-point-attributes": {
"mac-address": "00:00:5e:00:53:d4"
}
},
{
"tp-id": "1-2-1",
"ietf-l2-topology:l2-termination-point-attributes": {
"mac-address": "00:00:5e:00:53:d1"
}
},
{
"tp-id": "1-3-1",
"ietf-l2-topology:l2-termination-point-attributes": {
"mac-address": "00:00:5e:00:53:d2"
}
}
],
"ietf-l2-topology:l2-node-attributes": {
"management-address": [
"192.0.2.1",
"2001:db8:0:1::"
]
}
},
{
"node-id": "D2",
"ietf-network-topology:termination-point": [
{
"tp-id": "2-0-1",
"ietf-l2-topology:l2-termination-point-attributes": {
"mac-address": "00:00:5e:00:53:e0"
}
},
{
"tp-id": "2-1-1",
"ietf-l2-topology:l2-termination-point-attributes": {
"mac-address": "00:00:5e:00:53:e1"
}
},
{
"tp-id": "2-3-1",
"ietf-l2-topology:l2-termination-point-attributes": {
"mac-address": "00:00:5e:00:53:e2"
}
}
],
"ietf-l2-topology:l2-node-attributes": {
"management-address": [
"192.0.2.2",
"2001:db8:0:2::"
]
}
},
{
"node-id": "D3",
"ietf-network-topology:termination-point": [
{
"tp-id": "3-1-1",
"ietf-l2-topology:l2-termination-point-attributes": {
"mac-address": "00:00:5e:00:53:f0"
}
},
{
"tp-id": "3-2-1",
"ietf-l2-topology:l2-termination-point-attributes": {
"mac-address": "00:00:5e:00:53:f1"
}
}
],
"ietf-l2-topology:l2-node-attributes": {
"management-address": [
"192.0.2.3",
"2001:db8:0:3::"
]
}
}
],
"ietf-network-topology:link": [
{
"link-id": "D1,1-2-1,D2,2-1-1",
"source": {
"source-node": "D1",
"source-tp": "1-2-1"
},
"destination": {
"dest-node": "D2",
"dest-tp": "2-1-1"
},
"ietf-l2-topology:l2-link-attributes": {
"rate": "1000"
}
},
{
"link-id": "D2,2-1-1,D1,1-2-1",
"source": {
"source-node": "D2",
"source-tp": "2-1-1"
},
"destination": {
"dest-node": "D1",
"dest-tp": "1-2-1"
},
"ietf-l2-topology:l2-link-attributes": {
"rate": "1000"
}
},
{
"link-id": "D1,1-3-1,D3,3-1-1",
"source": {
"source-node": "D1",
"source-tp": "1-3-1"
},
"destination": {
"dest-node": "D3",
"dest-tp": "3-1-1"
},
"ietf-l2-topology:l2-link-attributes": {
"rate": "1000"
}
},
{
"link-id": "D3,3-1-1,D1,1-3-1",
"source": {
"source-node": "D3",
"source-tp": "3-1-1"
},
"destination": {
"dest-node": "D1",
"dest-tp": "1-3-1"
},
"ietf-l2-topology:l2-link-attributes": {
"rate": "1000"
}
},
{
"link-id": "D2,2-3-1,D3,3-2-1",
"source": {
"source-node": "D2",
"source-tp": "2-3-1"
},
"destination": {
"dest-node": "D3",
"dest-tp": "3-2-1"
},
"ietf-l2-topology:l2-link-attributes": {
"rate": "1000"
}
},
{
"link-id": "D3,3-2-1,D2,2-3-1",
"source": {
"source-node": "D3",
"source-tp": "3-2-1"
},
"destination": {
"dest-node": "D2",
"dest-tp": "2-3-1"
},
"ietf-l2-topology:l2-link-attributes": {
"rate": "1000"
}
}
]
}
]
}
}Acknowledgements 💜
The authors would like to thank everyone who sent in comments and suggestions: Susan Hares, Alia Atlas, Juergen Schoenwaelder, Mach Chen, Alexander Clemm, Sriganesh Kini, Oscar Gonzalez de Dios, Stig Venaas, Christian Huitema, Meral Shirazipour, Benjamin Kaduk, and Don Fedyk. 🫶
Huge thanks to Ladislav Lhotka for the yang-doctors review! 🌸
Authors' Addresses 🎀
Jie Dong Huawei Huawei Campus No. 156 Beiqing Rd. Beijing 100095 China
Email: jie.dong@huawei.com
Xiugang Wei Huawei Huawei Campus No. 156 Beiqing Rd. Beijing 100095 China
Email: weixiugang@huawei.com
Qin Wu Huawei 101 Software Avenue Yuhua District Nanjing 210012 China
Email: bill.wu@huawei.com
Mohamed Boucadair Orange Rennes 35000 France
Email: mohamed.boucadair@orange.com
Anders Liu Tecent Yinke Building 38 Haidian St Haidian District Beijing 100080 China
Email: andersliu@tencent.com
That's the whole thing, bestie! 🌈👑 Ily for reading all of it 💅💖
📦 where this page comes from
- ietf: rfc8944 2020-11
- 💖 girlified by claude-haiku-5-5 on : a language model's rewrite of the original, under its terms