Network Working Group J. Dong
Internet-Draft X. Wei
Intended status: Standards Track Q. Wu
Expires: September 12, 2020 Huawei
M. Boucadair
Orange
A. Liu
Tecent
March 11, 2020
A YANG Data Model for Layer-2 Network Topologies
draft-ietf-i2rs-yang-l2-network-topology-13
Abstract
This document defines a YANG data model for Layer 2 network
topologies.
Editorial Note (To be removed by RFC Editor)
Please update these statements within the document with the RFC
number to be assigned to this document:
o "This version of this YANG module is part of RFC XXXX;"
o "RFC XXXX: A YANG Data Model for Layer-2 Network Topologies";
o reference: RFC XXXX
Please update the "revision" date of the YANG module.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 12, 2020.
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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
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Layer 2 Topology Model . . . . . . . . . . . . . . . . . . . 3
4. Layer 2 Topology YANG Module . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
6. Security Considerations . . . . . . . . . . . . . . . . . . . 21
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 23
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
8.1. Normative References . . . . . . . . . . . . . . . . . . 23
8.2. Informative References . . . . . . . . . . . . . . . . . 24
Appendix A. Companion YANG Module for Non-NMDA Compliant
Implementations . . . . . . . . . . . . . . . . . . 25
Appendix B. An Example . . . . . . . . . . . . . . . . . . . . . 29
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34
1. Introduction
[RFC8345] defines the YANG [RFC6020] [RFC7950] data models of the
abstract (generic) network and network topology. Such models can be
augmented with technology-specific details to build more specific
topology models.
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. A sample example is
provided in Appendix B.
This document uses the common YANG types defined in [RFC6991] and
adopts the Network Management Datastore Architecture (NMDA
[RFC8342]).
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The terminology for describing YANG modules is defined in [RFC7950].
The meanings of the symbols used in the tree diagram are defined in
[RFC8340].
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.
3. Layer 2 Topology Model
The Layer 2 network topology YANG module is designed to be generic
and applicable to Layer 2 networks built with different L2
technologies. It can be used to describe both the physical and the
logical (virtual) L2 network topologies.
The relationship between the Layer 2 topology module and the generic
network and network topology module is shown in Figure 1. In order
to represent a Layer 2 network topology, the generic network and
topology models are augmented with Layer-2 specific information, such
as the identifiers, identities (e.g., Provider Backbone
Bridging[IEEE802.1ah] or QinQ[IEEE802.1ad]), attributes, and states
of the Layer-2 networks, nodes, links, and termination points. Some
of the information may be collected via Link Layer Discovery Protocol
(LLDP) [IEEE802.1AB] or other Layer-2 protocols, and some of them may
be locally configured.
+---------------------+
| ietf-network |
+----------^----------+
|
|
+---------------------+
|ietf-network-topology|
+----------^----------+
|
|
+----------^----------+
| ietf-l2-topology |
+---------------------+
Figure 1: Layer-2 Topology YANG Module Structure
The structure of "ietf-l2-topology" YANG module is depicted in the
following tree diagram:
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module: ietf-l2-topology
augment /nw:networks/nw:network/nw:network-types:
+--rw l2-network!
augment /nw:networks/nw:network:
+--rw l2-network-attributes
+--rw name? string
+--rw flag* l2-flag-type
augment /nw:networks/nw:network/nw:node:
+--rw l2-node-attributes
+--rw name? string
+--rw description? string
+--rw management-address* inet:ip-address
+--rw sys-mac-address? yang:mac-address
+--rw management-vid? dot1q-types:vlanid {VLAN}?
+--rw flag* node-flag-type
augment /nw:networks/nw:network/nt:link:
+--rw l2-link-attributes
+--rw name? string
+--rw flag* link-flag-type
+--rw rate? decimal64
+--rw delay? uint32
+--rw srlg* uint32
augment /nw:networks/nw:network/nw:node/nt:termination-point:
+--rw l2-termination-point-attributes
+--rw description? string
+--rw maximum-frame-size? uint32
+--rw (l2-termination-point-type)?
| +--:(ethernet)
| | +--rw mac-address? yang:mac-address
| | +--rw eth-encapsulation? identityref
| | +--rw lag? boolean
| | +--rw member-link-tp* leafref
| | +--rw mode? neg-mode
| | +--rw port-vlan-id? dot1q-types:vlanid {VLAN}?
| | +--rw vlan-id-name* [vlan-id] {VLAN}?
| | | +--rw vlan-id dot1q-types:vlanid
| | | +--rw vlan-name? string
| | +--rw qinq* [svlan-id cvlan-id] {QinQ}?
| | | +--rw svlan-id dot1q-types:vlanid
| | | +--rw cvlan-id dot1q-types:vlanid
| | +--rw vxlan {VXLAN}?
| | +--rw vni-id? vni
| +--:(legacy)
| +--rw layer-2-address? yang:phys-address
| +--rw encapsulation? identityref
+--ro tp-state? enumeration
notifications:
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+---n l2-node-event
| +--ro event-type? l2-network-event-type
| +--ro node-ref? leafref
| +--ro network-ref? -> /nw:networks/network/network-id
| +--ro l2-network!
| +--ro l2-node-attributes
| +--ro name? string
| +--ro description? string
| +--ro management-address* inet:ip-address
| +--ro sys-mac-address? yang:mac-address
| +--ro management-vid? dot1q-types:vlanid {VLAN}?
| +--ro flag* node-flag-type
+---n l2-link-event
| +--ro event-type? l2-network-event-type
| +--ro link-ref? leafref
| +--ro network-ref? -> /nw:networks/network/network-id
| +--ro l2-network!
| +--ro l2-link-attributes
| +--ro name? string
| +--ro flag* link-flag-type
| +--ro rate? decimal64
| +--ro delay? uint32
| +--ro srlg* uint32
+---n l2-termination-point-event
+--ro event-type? l2-network-event-type
+--ro tp-ref? leafref
+--ro node-ref? leafref
+--ro network-ref?
| -> /nw:networks/network/network-id
+--ro l2-network!
+--ro l2-termination-point-attributes
+--ro description? string
+--ro maximum-frame-size? uint32
+--ro (l2-termination-point-type)?
| +--:(ethernet)
| | +--ro mac-address? yang:mac-address
| | +--ro eth-encapsulation? identityref
| | +--ro lag? boolean
| | +--ro member-link-tp* leafref
| | +--ro mode? neg-mode
| | +--ro port-vlan-id? dot1q-types:vlanid
| | | {VLAN}?
| | +--ro vlan-id-name* [vlan-id] {VLAN}?
| | | +--ro vlan-id dot1q-types:vlanid
| | | +--ro vlan-name? string
| | +--ro qinq* [svlan-id cvlan-id] {QinQ}?
| | | +--ro svlan-id dot1q-types:vlanid
| | | +--ro cvlan-id dot1q-types:vlanid
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| | +--ro vxlan {VXLAN}?
| | +--ro vni-id? vni
| +--:(legacy)
| +--ro layer-2-address? yang:phys-address
| +--ro encapsulation? identityref
+--ro tp-state? enumeration
The Layer-2 topology YANG module augments the 'ietf-network' and
'ietf-network-topology' YANG modules as follows:
o A new network type "l2-network-type" is introduced. This is
represented by a container object, and is inserted under the
"network-types" container of the generic 'ietf-network' module
defined in [RFC8345].
o Additional network attributes are introduced in a grouping "l2-
network-attributes", which augments the "network" list of the
'ietf-network' module. The attributes include Layer-2 network
name and a set of flags. Each type of flag is represented by a
separate identity.
o Additional data objects for Layer-2 nodes are introduced by
augmenting the "node" list of the generic 'ietf-network' module.
New objects include Layer-2 node identifier, description,
management address, and a set of flags.
o Additional data objects for Layer-2 termination points are
introduced by augmenting the "termination-point" list of the
'ietf-network-topology' module defined in [RFC8345]. New objects
include Layer-2 termination point descriptions, Layer-2
termination point type specific attributes and Layer-2 termination
point states.
o Links in the 'ietf-network-topology' module are augmented as well
with a set of Layer-2 parameters, allowing to associate a link
with a name, a set of Layer-2 link attributes and flags.
o Some optional L2 technology specific attributes are introduced in
this module as Layer-2 features because these attributes may be
useful to expose to above services/applications. Note that
learning or configuring advanced L2 technology-specific attributes
is not within the scope of the Layer-2 Topology YANG module;
dedicated YANG modules should be used instead (e.g.,
[I-D.ietf-trill-yang]).
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4. Layer 2 Topology YANG Module
This module uses types defined in [RFC6991], [RFC7224],
[IEEE802.1Qcp], and [RFC8345]. It also references [RFC4761],
[RFC4762], and [RFC4202].
<CODE BEGINS> file "ietf-l2-topology@2019-10-15.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
"Section 4 of RFC 6991";
}
import ietf-yang-types {
prefix yang;
reference
"Section 3 of RFC 6991";
}
import iana-if-type {
prefix ift;
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: <http://tools.ietf.org/wg/i2rs/>
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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 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 XXXX: A YANG Data Model for Layer-2 Network Topologies
see the RFC itself for full legal notices.";
revision 2019-10-15 {
description
"Initial revision";
reference
"RFC XXXX: A YANG Data Model for Layer-2 Network
Topologies";
}
/*
* Typedefs
*/
typedef vni {
type uint32 {
range "1..16777215";
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}
description
"VxLAN Network Identifier";
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 trill topology
type.";
}
typedef node-flag-type {
type identityref {
base flag-identity;
}
description
"Node flag attributes.The physical node can be
one example of node flag attribute.";
}
typedef link-flag-type {
type identityref {
base flag-identity;
}
description
"Link flag attributes. One example of link flag
attribute is the pseudowire.";
}
typedef l2-network-event-type {
type enumeration {
enum add {
value 0;
description
"A Layer-2 node or link or termination-point
has been added.";
}
enum remove {
value 1;
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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.";
}
// l2-topology-event-type
typedef neg-mode {
type enumeration {
enum full-duplex {
description
"Indicates full-duplex mode.";
}
enum auto-neg {
description
"Indicates auto-negotiation mode.";
}
enum half-duplex {
description
"Indicates half-duplex mode.";
}
}
description
"Indicates the type of the negotiation mode.";
}
// negotiation mode
/*
* Features
*/
feature VLAN {
description
"Indicates that the system supports the
vlan functions (also known as an IEEE 802.1Q tag).";
}
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feature QinQ {
description
"Indicates that the system supports the
qinq functions (also known as IEEE 802.1ad double tag)";
}
feature VXLAN {
description
"Indicates that the device supports VXLAN functions.";
reference
"RFC 7348: Virtual eXtensible Local Area Network (VXLAN):
A Framework for Overlaying Virtualized Layer 2 Networks
over Layer 3 Networks";
}
/*
* Identities
*/
identity flag-identity {
description
"Base type for flags.";
}
identity eth-encapsulation-type {
base ift: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
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"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
"TRILL encapsulation.";
}
identity vpls {
base eth-encapsulation-type;
description
"Ethernet VPLS interface encapsulation.";
}
identity vxlan {
base eth-encapsulation-type;
description
"VXLAN MAC in UDP encapsulation.";
}
/*
* Groupings
*/
grouping l2-network-type {
description
"Indicates the topology type to be L2.";
container l2-network {
presence "indicates L2 Network";
description
"The presence of the container node indicates
L2 Topology.";
}
}
grouping l2-network-attributes {
description
"L2 Topology scope attributes.";
container l2-network-attributes {
description
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"Contains L2 network attributes.";
leaf name {
type string;
description
"Name of the L2 network.";
}
leaf-list flag {
type l2-flag-type;
description
"L2 network 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 description {
type string;
description
"Node description.";
}
leaf-list management-address {
type inet:ip-address;
description
"System management address.";
}
leaf sys-mac-address {
type yang:mac-address;
description
"System MAC-address.";
}
leaf management-vid {
if-feature "VLAN";
type dot1q-types:vlanid;
description
"System management VID.";
}
leaf-list flag {
type node-flag-type;
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description
"Node operational flags.";
}
}
}
// grouping l2-node-attributes
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 flag {
type link-flag-type;
description
"Link flags.";
}
leaf rate {
type decimal64 {
fraction-digits 2;
}
units "Mbps";
description
"Link rate.";
}
leaf delay {
type uint32;
units "microseconds";
description
"Link delay in microseconds.";
}
leaf-list srlg {
type uint32;
description
"List of Shared Risk Link Groups
this link belongs to.";
reference
"RFC 4202: Routing Extensions in Support of
Generalized Multi-Protocol Label Switching
(GMPLS)";
}
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}
}
// grouping l2-link-attributes
grouping l2-termination-point-attributes {
description
"L2 termination point attributes";
container l2-termination-point-attributes {
description
"Containing L2 termination point attributes.";
leaf description {
type string;
description
"Port description.";
}
leaf maximum-frame-size {
type uint32;
description
"Maximum L2 frame size. If L2 frame is an Ethernet
frame, the Ethernet header should be included;
if L2 frame is other type (e.g.,PPP), the L2
header should be included.";
}
choice l2-termination-point-type {
description
"Indicates termination-point type
specific attributes.";
case ethernet {
leaf mac-address {
type yang:mac-address;
description
"Interface MAC address.";
}
leaf eth-encapsulation {
type identityref {
base eth-encapsulation-type;
}
description
"Encapsulation type of this
termination point.";
}
leaf lag {
type boolean;
default "false";
description
"Defines whether lag is support or not.";
}
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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
"Member link termination points.";
}
leaf mode {
type neg-mode;
default "auto-neg";
description
"Exposes the negotiation mode.";
}
leaf port-vlan-id {
when "derived-from-or-self(../eth-encapsulation"+
", 'l2t:vlan')" {
description
"Only applies when the type of the Ethernet
encapsulation is 'vlan'.";
}
if-feature "VLAN";
type dot1q-types:vlanid;
description
"Port VLAN ID is the VLAN id that
will be assigned to any untagged frames entering
the switch on the specific port.";
}
list vlan-id-name {
when "derived-from-or-self(../eth-encapsulation"+
", 'l2t:vlan')" {
description
"Only applies when the type of the Ethernet
encapsulation is 'vlan'.";
}
if-feature "VLAN";
key "vlan-id";
description
"Interface configured VLANs.";
leaf vlan-id {
type dot1q-types:vlanid;
description
"VLAN ID.";
}
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leaf vlan-name {
type string {
length "1..31";
}
description
"VLAN name.";
}
}
list qinq {
when "derived-from-or-self(../eth-encapsulation"+
", 'l2t:qinq')" {
description
"Only applies when the type of the Ethernet
encapsulation is 'qinq'.";
}
if-feature "QinQ";
key "svlan-id cvlan-id";
description
"Interface configured SVLANs and CVLANs.";
leaf svlan-id {
type dot1q-types:vlanid;
description
"SVLAN ID.";
}
leaf cvlan-id {
type dot1q-types:vlanid;
description
"CVLAN ID.";
}
}
container vxlan {
when "derived-from-or-self(../eth-encapsulation"+
", '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.";
}
}
//case ethernet
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case legacy {
leaf layer-2-address {
type yang:phys-address;
description
"Interface Layer 2 address.";
}
leaf encapsulation {
type identityref {
base ift:iana-interface-type;
}
description
"Other legacy encapsulation type of this
termination point.";
}
}
//case legacy such as atm, ppp, hdlc, etc.
}
//choice termination-point-type
leaf tp-state {
type enumeration {
enum in-use {
value 1;
description
"The termination point is in forwarding state.";
}
enum blocking {
value 2;
description
"The termination point is in blocking state.";
}
enum down {
value 3;
description
"The termination point is in down state.";
}
enum others {
value 4;
description
"The termination point is in other state.";
}
}
config false;
description
"State of the termination point.";
}
}
}
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// grouping l2-termination-point-attributes
/*
* Data nodes
*/
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-network' {
description
"Augmentation parameters apply only for networks
with L2 topology.";
}
description
"Configuration parameters for the L2 network
as a whole.";
uses l2-network-attributes;
}
augment "/nw:networks/nw:network/nw:node" {
when '/nw:networks/nw:network/nw:network-types/l2t:l2-network' {
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-network' {
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-network' {
description
"Augmentation parameters apply only for networks
with L2 topology.";
}
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description
"Augments L2 topology termination point information.";
uses l2-termination-point-attributes;
}
/*
* Notifications
*/
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;
}
}
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<CODE ENDS>
5. IANA Considerations
This document requests IANA to register 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.
This document requests IANA to register 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 XXXX
name: ietf-l2-topology-state
namespace: urn:ietf:params:xml:ns:yang:ietf-l2-topology-state
prefix: l2t-s
reference: RFC XXXX
These modules are not maintained by IANA.
6. Security Considerations
The YANG module specified in this document defines a schema for data
that is designed to be accessed via network management protocols such
as NETCONF [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.
In general, Layer 2 network topologies are system-controlled and
provide ephemeral topology information. In an NMDA-complient server,
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they are only part of <operational> which provides read-only access
to clients, they are less vulnerable. That said, the YANG module
does in principle allow information to be configurable.
The Layer 2 topology module define 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, 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, leading to disruption
of services provided via this topology might be disrupted. For those
reasons, it is important that the NETCONF access control model 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 in the ietf-network module:
o 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.
o l2-node-attributes: A malicious client could attempt to sabotage
the configuration of important node attributes, such as the name
or the management-address.
o 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.
o l2-termination-point-attributes: A malicious client could attempt
to sabotage the configuration of important termination point
attributes, such as the maximum-frame-size.
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7. Acknowledgements
The authors would like to acknowledge the comments and suggestions
received from Susan Hares, Alia Atlas, Juergen Schoenwaelder, Mach
Chen, Alexander Clemm, Sriganesh Kini, and Oscar Gonzalez de Dios.
8. References
8.1. Normative References
[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>.
[RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005,
<https://www.rfc-editor.org/info/rfc4202>.
[RFC4761] Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private
LAN Service (VPLS) Using BGP for Auto-Discovery and
Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007,
<https://www.rfc-editor.org/info/rfc4761>.
[RFC4762] Lasserre, M., Ed. and V. Kompella, Ed., "Virtual Private
LAN Service (VPLS) Using Label Distribution Protocol (LDP)
Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007,
<https://www.rfc-editor.org/info/rfc4762>.
[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>.
[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>.
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[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>.
[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>.
[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>.
8.2. Informative References
[I-D.ietf-trill-yang]
Weiguo, H., Yizhou, L., Kumar, D., Durrani, M., Zhai, H.,
and L. Xia, "TRILL YANG Data Model", draft-ietf-trill-
yang-04 (work in progress), December 2015.
[IEEE802.1AB]
"Station and Media Access Control Connectivity Discovery",
IEEE Std 802.1AB-2016, March 2016.
[IEEE802.1ad]
"Virtual Bridged Local Area Networks Amendment 4: Provider
Bridges", IEEE Std 802.1ad-2005, May 2006.
[IEEE802.1ah]
"Virtual Bridged Local Area Networks Amendment 4: Provider
Bridges", IEEE Std 802.1ah-2008, August 2008.
[IEEE802.1Qcp]
"Bridges and Bridged Networks - Amendment: YANG Data
Model", IEEE Std 802.1Qcp-2018, September 2018.
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[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>.
[RFC6325] Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
Ghanwani, "Routing Bridges (RBridges): Base Protocol
Specification", RFC 6325, DOI 10.17487/RFC6325, July 2011,
<https://www.rfc-editor.org/info/rfc6325>.
[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>.
[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>.
[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>.
Appendix A. Companion YANG Module for Non-NMDA Compliant
Implementations
The YANG module ietf-l2-topology defined in this document augments
two modules, 'ietf-network' and 'ietf-network-topology', that are
designed to be used in conjunction with implementations that support
the Network Management Datastore Architecture (NMDA) defined in
[RFC8342]. In order to allow implementations to use the model even
in cases when NMDA is not supported, a set of companion modules have
been defined that represent a state model of networks and network
topologies, 'ietf-network-state' and 'ietf-network-topology-state',
respectively.
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In order to be able to use the model for layer 2 topologies defined
in this document in conjunction with non-NMDA compliant
implementations, a corresponding companion module is defined that
represent the operational state of layer 2 network topologies. The
module 'ietf-l2-topology-state' mirrors the module 'ietf-l2-topology'
defined earlier in this document. However, it augments 'ietf-
network-state' and 'ietf-network-topology-state' (instead of 'ietf-
network' and 'ietf-network-topology') and all its data nodes are non-
configurable.
The companion module 'ietf-l2-topology' SHOULD NOT be supported by
implementations that support NMDA. It is for this reason that this
module is defined in the informative Appendix.
As the structure of this modules mirrors that of its underlying
modules, the YANG tree is not depicted separately.
<CODE BEGINS> file "ietf-l2-topology-state@2019-06-04.yang"
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 XXXX: 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
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<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
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of
RFC XXXX: A YANG Data Model for Layer-2 Network Topologies
see the RFC itself for full legal notices.";
revision "2019-06-04" {
description "Initial revision";
reference "RFC XXXX: A YANG Data Model for Layer-2 Network
Topologies";
}
/*
* Data nodes
*/
augment "/nw-s:networks/nw-s:network/nw-s:network-types" {
description
"Introduce new network type for L2 topology";
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uses l2t:l2-network-type;
}
augment "/nw-s:networks/nw-s:network" {
when "/nw-s:networks/nw-s:network/nw-s:network-types/"+
"l2t-s:l2-network" {
description
"Augmentation parameters apply only for networks
with L2 topology.";
}
description
"Configuration parameters for the L2 network
as a whole.";
uses l2t:l2-network-attributes;
}
augment "/nw-s:networks/nw-s:network/nw-s:node" {
when "../nw-s:network-types/l2t-s:l2-network" {
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-network" {
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-network" {
description
"Augmentation parameters apply only for networks
with L2 topology.";
}
description
"Augments L2 topology termination point information.";
uses l2t:l2-termination-point-attributes;
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}
/*
* 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 a 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;
}
}
<CODE ENDS>
Appendix B. An Example
This section contains an example of an instance data tree in JSON
encoding [RFC7951]. The example instantiates "ietf-l2- topology" for
the topology that is depicted in the following diagram. There are
three nodes: D1, D2, and D3. D1 has three termination points: 1-0-1,
1-2-1, and 1-3-1. D2 has three termination points as well: 2-1-1,
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2-0-1, and 2-3-1. D3 has two termination points: 3-1-1 and 3-2-1.
In addition, there are six links, two between each pair of nodes,
with one going in each direction.
+------------+ +------------+
| D1 | | D2 |
/-\ /-\ /-\ /-\
| | 1-0-1 | |---------------->| | 2-1-1 | |
| | 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
The corresponding instance data tree is depicted as below. Note that
some lines have been wrapped to adhere to the 72-character line
limitation of RFCs.
{
"ietf-network:networks": {
"network": [
{
"network-types": {
"ietf-l2-topology:l2-network": {}
},
"network-id": "l2-topo-example",
"node": [
{
"node-id": "D1",
"termination-point": [
{
"tp-id": "1-0-1",
"ietf-l2-topology:
l2-termination-point-attributes": {
"mac-address": "00-00-5E-00-53-D0"
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}
},
{
"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"]
}
},
{
"node-id": "D2",
"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"]
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}
},
{
"node-id": "D3",
"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"]
}
}
],
"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",
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"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"
}
},
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Internet-Draft Layer-2 Network Topology Data Model March 2020
{
"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"
}
}
]
}
]
}
}
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
Dong, et al. Expires September 12, 2020 [Page 34]
Internet-Draft Layer-2 Network Topology Data Model March 2020
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
Dong, et al. Expires September 12, 2020 [Page 35]
