Transport Northbound Interface Applicability Statement
draft-ietf-ccamp-transport-nbi-app-statement-15
| Document | Type | Active Internet-Draft (ccamp WG) | |
|---|---|---|---|
| Authors | Italo Busi , Daniel King , Haomian Zheng , Yunbin Xu | ||
| Last updated | 2022-07-04 | ||
| Replaces | draft-ietf-ccamp-transport-nbi-use-cases | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Informational | ||
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| Stream | WG state | Waiting for WG Chair Go-Ahead | |
| Associated WG milestone |
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| Document shepherd | Daniele Ceccarelli | ||
| Shepherd write-up | Show Last changed 2021-03-25 | ||
| IESG | IESG state | I-D Exists (IESG: Dead) | |
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| Responsible AD | John Scudder | ||
| Send notices to | daniele.ceccarelli@ericsson.com |
draft-ietf-ccamp-transport-nbi-app-statement-15
CCAMP Working Group I. Busi, Ed.
Internet-Draft Huawei
Intended status: Informational D. King, Ed.
Expires: 5 January 2023 Old Dog Consulting
H. Zheng, Ed.
Huawei
Y. Xu, Ed.
CAICT
4 July 2022
Transport Northbound Interface Applicability Statement
draft-ietf-ccamp-transport-nbi-app-statement-15
Abstract
This document provides an analysis of the applicability of the YANG
models defined by the IETF (in particular in the Traffic Engineering
Architecture and Signaling (TEAS) and Common Control and Measurement
Plane (CCAMP) working groups) to support ODU transit services,
transparent client services, and Ethernet Private Line/Ethernet
Virtual Private Line (EPL/EVPL) services over Optical Transport
Network (OTN) in single and multi-domain network scenarios.
This document also describes how existing YANG models can be used
through several worked examples and JSON fragments.
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 5 January 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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 Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. The Scope of this Document . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Conventions Used in this Document . . . . . . . . . . . . . . 7
3.1. Topology and Traffic Flow Processing . . . . . . . . . . 7
4. Scenarios Description . . . . . . . . . . . . . . . . . . . . 8
4.1. Reference Network . . . . . . . . . . . . . . . . . . . . 8
4.2. Topology Abstractions . . . . . . . . . . . . . . . . . . 12
4.3. Service Configuration . . . . . . . . . . . . . . . . . . 14
4.3.1. ODU Transit . . . . . . . . . . . . . . . . . . . . . 14
4.3.2. EPL over ODU . . . . . . . . . . . . . . . . . . . . 15
4.3.3. Transparent Client Services . . . . . . . . . . . . . 16
4.3.4. EVPL over ODU . . . . . . . . . . . . . . . . . . . . 17
4.4. Multi-Function Access Links . . . . . . . . . . . . . . . 18
4.5. Protection and Restoration Configuration . . . . . . . . 19
4.5.1. Linear Protection (End-to-End) . . . . . . . . . . . 20
4.5.2. Segmented Protection . . . . . . . . . . . . . . . . 21
4.6. Event Notifications and Alarms . . . . . . . . . . . . . 21
4.7. Path Computation with Constraints . . . . . . . . . . . . 22
5. YANG Model Analysis . . . . . . . . . . . . . . . . . . . . . 23
5.1. YANG Models for Topology Abstraction . . . . . . . . . . 23
5.1.1. Domain 1 Black Topology Abstraction . . . . . . . . . 24
5.1.2. Domain 2 Black Topology Abstraction . . . . . . . . . 28
5.1.3. Domain 3 White Topology Abstraction . . . . . . . . . 29
5.1.4. Multi-domain Topology Merging . . . . . . . . . . . . 29
5.2. YANG Models for Service Configuration . . . . . . . . . . 32
5.2.1. ODU Transit Service . . . . . . . . . . . . . . . . . 35
5.2.2. EPL over ODU Service . . . . . . . . . . . . . . . . 37
5.2.3. Other OTN Client Services . . . . . . . . . . . . . . 40
5.2.4. EVPL over ODU Service . . . . . . . . . . . . . . . . 41
5.3. YANG Models for Protection Configuration . . . . . . . . 42
5.3.1. Linear Protection (end-to-end) . . . . . . . . . . . 42
5.3.2. Segmented Protection . . . . . . . . . . . . . . . . 44
5.4. Notifications . . . . . . . . . . . . . . . . . . . . . . 45
5.5. Path Computation with Constraints . . . . . . . . . . . . 46
6. Security Considerations . . . . . . . . . . . . . . . . . . . 46
6.1. OTN Security . . . . . . . . . . . . . . . . . . . . . . 47
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7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 47
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 47
8.1. Normative References . . . . . . . . . . . . . . . . . . 47
8.2. Informative References . . . . . . . . . . . . . . . . . 49
Appendix A. Validating a JSON fragment against a YANG Model . . 51
A.1. JSON CODE . . . . . . . . . . . . . . . . . . . . . . . . 51
A.2. Manipulation of JSON fragments . . . . . . . . . . . . . 52
A.3. Comments in JSON fragments . . . . . . . . . . . . . . . 53
A.4. Validation of JSON fragments: DSDL-based approach . . . . 53
A.5. Validation of JSON fragments: why not using an XSD-based
approach . . . . . . . . . . . . . . . . . . . . . . . . 54
Appendix B. Detailed JSON Examples . . . . . . . . . . . . . . . 54
B.1. JSON Examples for Topology Abstractions . . . . . . . . . 54
B.1.1. JSON Code: mpi1-otn-topology.json . . . . . . . . . . 55
B.1.2. JSON Code: mpi1-eth-topology.json . . . . . . . . . . 77
B.2. JSON Examples for Service Configuration . . . . . . . . . 82
B.2.1. JSON Code: mpi1-odu2-service-config.json . . . . . . 82
B.2.2. JSON Code: mpi1-odu2-tunnel-config.json . . . . . . . 85
B.2.3. JSON Code: mpi1-epl-service-config.json . . . . . . . 88
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 89
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 91
1. Introduction
Transport network domains, including Optical Transport Network (OTN)
and Wavelength Division Multiplexing (WDM) networks are typically
deployed based on a single vendor or a single technology platform.
They are often managed using proprietary interfaces to dedicated
Element Management Systems (EMS), Network Management Systems (NMS)
and increasingly Software Defined Network (SDN) controllers.
Support of packet connectivity services over a transport network
domain is critical for a wide range of applications and services,
including data center and LAN interconnects, Internet service
backhauling, mobile backhaul and enterprise Carrier Ethernet
services. An explicit goal of operators is to automate the setup of
these connectivity services across multiple transport network
domains, that may utilize different technologies.
A well-defined common open interface to each domain controller or a
management system is required for network operators to control multi-
vendor and multi-domain networks and also enable coordination and
automation of service provisioning. This is facilitated by using
standardized data models (e.g., YANG models), and an appropriate
protocol (e.g., RESTCONF [RFC8040]).
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This document examines the applicability of the YANG models defined
by the IETF (in particular in the Traffic Engineering Architecture
and Signaling (TEAS) and Common Control and Measurement Plane (CCAMP)
working groups) to support OTN in a single and multi-domain network
scenarios.
1.1. The Scope of this Document
This document assumes a reference architecture, including interfaces,
based on the Framework for Abstraction and Control of Traffic-
Engineered Networks (ACTN), defined in [RFC8453].
The focus of this document is on the interface between the Multi
Domain Service Coordinator (MDSC) and a Provisioning Network
Controller (PNC), controlling a transport network domain, called
MDSC-PNC Interface (MPI) in [RFC8453].
It is worth noting that the same MPI analyzed in this document could
be used between hierarchical MDSC controllers, as shown in Figure 4
of [RFC8453].
A detailed analysis of the interface between the Customer Network
Controller (CNC) and the MDSC, called CNC-MDSC Interface (CMI) in
[RFC8453], as well as the interface between service and network
orchestrators are outside the scope of this document. However, when
needed, this document describes some considerations and assumptions
about the information which needs to be provided at these interfaces.
The list of the IETF YANG models which apply to the ACTN MPI can be
found in [ACTN-YANG].
The Functional Requirements for the transport API as described in the
Optical Networking Foundation (ONF) document [ONF_TR-527] have been
taken as input for defining the reference scenarios analyzed in this
document.
The analysis provided in this document confirms that the IETF YANG
models defined in [RFC8453], [RFC8795], [OTN-TOPO], [CLIENT-TOPO],
[TE-TUNNEL], [PATH-COMPUTE], [OTN-TUNNEL], and [CLIENT-SIGNAL] can be
used together to control a multi-domain OTN network to support
different types of multi-domain services, such as Optical Data Unit
(ODU) transit services, Transparent client services and EPL/EVPL
Ethernet Private Line/Ethernet Virtual Private Line (EPL/EVPL)
services, over a multi-domain OTN connection, satisfying also the
requirements in [ONF_TR-527].
2. Terminology
Domain A domain, as defined in [RFC4655], is "any collection of
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network elements within a common sphere of address management or
path computation responsibility". Specifically, within this
document, we mean a part of an operator's network that is under
common management (i.e., under shared operational management using
the same instances of a tool and the same policies). Network
elements will often be grouped into domains based on technologies,
vendor profiles, or geographic proximity.
CNC Customer Network Controller
Connection The data plane configuration of an LSP: within this
document it is typically an ODU LSP. An end-to-end connection/LSP
represents an entire connection between the connection node end-
points. A connection/LSP segment represents a portion of the end-
to-end connection.
Connectivity Service A connectivity service, in the context of this
document, can be considered as a connection between customer
sites, across the network operator's network [RFC8309].
E-LINE Ethernet Line
EPL Ethernet Private Line
EVPL Ethernet Virtual Private Line
ILL Inter-Layer Lock
Link It is used to represent the adjacency between two nodes.
The term physical link represents a link between two physical
nodes. The term OTN link represents a link between two OTN nodes.
LSP Label Switched Path
LTP Link Termination Point
MDSC Multi-Domain Service Coordinator
Network Configuration As described in [RFC8309] it describes the
instructions provided to a controller on how to configure parts of
a network.
ODU Optical Channel Data Unit
OTU Optical Channel Transport Unit
OTN Optical Transport Network
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PNC Provisioning Network Controller
Protection Switching Protection switching, as defined in
[ITU-T_G.808.1] and [RFC4427], provides the capability to switch
the traffic in case of network failures over pre-allocated
networks resources. Typically linear protection methods would be
used and configured to operate as 1+1 unidirectional, 1+1
bidirectional or 1:n bidirectional. This ensures fast and simple
service survivability.
Protection Transport Entity/LSP A protection transport entity/LSP,
as defined in [ITU-T_G.808.1] and [RFC4427], represents the path
where the "normal" user traffic is transported during protection
switching events (e.g., when the working transport entity/LSP
fails).
Restoration Restoration methods, as defined in [RFC4427], provide
the capability to reroute and restore traffic around network
failures without the necessity to allocate network resources as
required for dedicated 1+1 protection schemes. On the other hand,
restoration times are typically longer than protection switching
times.
Service Model As described in [RFC8309] it describes a service and
the parameters of the service in a portable way that can be used
uniformly and independent of the equipment and operating
environment.
TE Link As defined in [RFC8795], is an element of a TE topology,
presented as an edge on TE graph.
TE Tunnel As defined in [TE-TUNNEL], it is a connection-oriented
service provided by a layered network of delivery of a client's
data between source and destination tunnel termination points.
See also [TE-TUTORIAL].
TE Tunnel Segment As defined in [TE-TUNNEL], it is a part of a
multi-domain TE tunnel that spans. See also [TE-TUTORIAL].
TE Tunnel Hand-off It is an access or inter-domain LTP by which a
multi-domain TE tunnel enters or exits a given network domain.
See also [TE-TUTORIAL].
Note - The three definitions above are currently in [TE-TUTORIAL] but
it is expected that they will be moved to [TE-TUNNEL]. When this
happens, the reference will be updated and the [TE-TUTORIAL]
reference will be downgraded to Informative.
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TPN Tributary Port Number
TTP Tunnel Termination Point
Termination and Adaptation It represents the termination of a
server-layer connection at the node edge-point and the adaptation/
mapping of the client layer traffic over the terminated server-
layer connection.
Transparent Client As defined in [CLIENT-SIGNAL], it represents a
client-layer signal, such as Ethernet physical interfaces, FC,
STM- n, that cannot be switched but only mapped over a server-
layer TE Tunnel.
Working Transport Entity/LSP A working transport entity/LSP, as
defined in [ITU-T_G.808.1] and [RFC4427], represents the path
where the "normal" user traffic is transported.
UNI User Network Interface
3. Conventions Used in this Document
3.1. Topology and Traffic Flow Processing
The traffic flow between different nodes is specified as an ordered
list of nodes, separated with commas, indicating within the brackets
the processing within each node:
<node> [<processing>]{, <node> [<processing>]}
The order represents the order of traffic flow being forwarded
through the network.
The <processing> represents the type of processing performed by the
node, which can be just switching at a given layer "(switching-
layer)" or it can also include an adaptation of a client layer into a
server layer: "(client-layer) -> server-layer" or "client-layer ->
(server-layer)", where the round brackets are used to represent at
which layer (client layer or server layer) the node is switching.
For example, the following traffic flow:
R1 [(PKT) -> ODU2], S3 [(ODU2)], S5 [(ODU2)], S6 [(ODU2)],
R3 [ODU2 -> (PKT)]
Node R1 is switching at the packet (PKT) layer and mapping packets
into an ODU2 before transmission to node S3. Nodes S3, S5 and S6,
are switching at the ODU2 layer: S3 sends the ODU2 traffic to S5,
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which then sends it to S6 which finally sends to R3. Node R3
terminates the ODU2 from S6 before switching at the packet (PKT)
layer.
The paths of working and protection transport entities are specified
as an ordered list of nodes, separated with commas:
<node> {, <node>}
The order represents the order of traffic flow being forwarded
through the network in the forward direction. In the case of
bidirectional paths, the forward and backward directions are selected
arbitrarily, but the convention is consistent between working/
protection path pairs, as well as across multiple domains.
The use of curly brackets denotes multiple nodes in a list.
4. Scenarios Description
4.1. Reference Network
The physical topology of the reference network is shown in Figure 1.
It represents an OTN network composed of three transport network
domains that provide connectivity services to an IP customer network
through nine access links:
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........................
......... : :
: : Network domain 1 : .............
Customer: : : : :
domain : : S1 -------+ : : Network :
: : / \ : : domain 3 : ..........
R1 ------- S3 ----- S4 \ : : : :
: : \ \ S2 --------+ : :Customer
: : \ \ | : : \ : : domain
: : S5 \ | : : \ : :
R2 ------+ / \ \ | : : S31 --------- R5
: : \ / \ \ | : : / \ : :
R3 ------- S6 ---- S7 ---- S8 ------ S32 S33 ------ R6
: : / | | : : / \ / : :.......
R4 ------+ | | : :/ S34 : :
: :..........|.......|...: / / : :
........: | | /:.../.......: :
| | / / :
...........|.......|..../..../... :
: | | / / : ..............
: Network | | / / : :
: domain 2 | | / / : :Customer
: S11 ---- S12 / : : domain
: / | \ / : :
: S13 S14 | S15 ------------- R7
: | \ / \ | \ : :
: | S16 \ | \ : :
: | / S17 -- S18 --------- R8
: | / \ / : :
: S19 ---- S20 ---- S21 ------------ R9
: : :
:...............................: :.............
Figure 1: Reference network
This document assumes that all the Si transport network switching
nodes are capable of switching in the electrical domain (ODU
switching) moreover, all the Si-Sj OTN links within the transport
network (intra-domain or inter-domain) are 100G links while the
access Ri-Sj links are 10G links.
This document also assumes that within the transport network, the
physical/optical connections supporting the Si-Sj OTN links (up to
the OTU4 trail), are pre-provisioned using mechanisms that are
outside the scope of this document and are not exposed at the MPIs to
the MDSC.
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Different transmission technologies can be used on the access links
(e.g., Ethernet, Synchronous Transport Module (STM) and OTU).
Section 4.3 provides more details about the different assumptions on
the access links for different types of connectivity services, and
Section 4.4 describes the control of access links that can support
different technology configurations (e.g., STM-64, 10GE or OTU2)
depending on the type of service being configured (multi-function
access links).
To carry client signals (e.g., Ethernet or STM-N) over OTN, some ODU
termination and adaptation resources need to be available on the
physical edge nodes (e.g., node S3 and S18). The location of these
resources within the physical node is implementation-specific and
outside the scope of standardization. This document assumes that
these termination and adaptation resources are located on the
physical interfaces of the edge nodes terminating the access links.
In other words, each physical access link has a set of dedicated ODU
termination and adaptation resources.
The transport network control architecture, shown in Figure 2,
follows the ACTN architecture as defined in the ACTN framework
document [RFC8453], and uses the same functional components:
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--------------
| |
| CNC |
| |
--------------
|
....................|....................... CMI
|
----------------
| |
| MDSC |
| |
----------------
/ | \
/ | \
............../.....|......\................ MPIs
/ | \
/ ---------- \
/ | PNC2 | \
/ ---------- \
---------- | \
| PNC1 | ----- \
---------- ( ) ----------
| ( ) | PNC3 |
----- ( Network ) ----------
( ) ( Domain 2 ) |
( ) ( ) -----
( Network ) ( ) ( )
( Domain 1 ) ----- ( )
( ) ( Network )
( ) ( Domain 3 )
----- ( )
( )
-----
Figure 2: Controlling Hierarchies
The NEs within network domains 1, 2 and 3 of Figure 1 are controlled,
respectively, by PNC1, PNC2 and PNC3 of Figure 2. The MDSC control
the end-to-end network through the MPIs toward the underlying PNCs.
The ACTN framework facilitates separating the network and service
control from the underlying technology. It helps the customer to
define the network as desired by business needs. The CMI is defined
to keep a minimal level of dependency (or no dependency at all) from
the underlying network technologies. The MPI instead requires some
specialization according to the domain technology.
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The control interfaces within the scope of this document are the
three MPIs, as shown in Figure 2.
The split of functionality at the MPI in the ACTN architecture
between the MDSC and the PNCs, is equivalent to separation
functionality assumed in the ONF T-API interface, as described in the
ONF T-API multi-domain use cases [ONF_TR-527]. Furthermore, this
functional separation is similarly defined in the MEF PRESTO
interface between the Service Orchestration Functionality (SOF) and
the Infrastructure Control and Management (ICM) in the MEF LSO
Architecture [MEF55].
This document does not make any assumption about the control
architecture of the customer IP network: in line with [RFC8453], the
CNC is just a functional component within the customer control
architecture which is capable of requesting connectivity services on
demand between IP routers at the CMI.
The CNC can request connectivity services between IP routers which
can be attached to different transport network domains (e.g., between
R1 and R8 in Figure 1) or to the same transport network domain (e.g.,
between R1 and R3 in Figure 1). Since the CNC is not aware of the
transport network controller hierarchy, the mechanisms used by the
CNC to request connectivity services at the CMI is also unaware
whether the requested service spans a single-domain or multi-domains.
It is assumed that the CMI allows the CNC to provide all the
necessary information needed by the MDSC to understand the
connectivity service request and to determine the network
configurations to be requested, at the MPIs, to its underlying PNCs
to support the requested connectivity service.
The MDSC, after having received a single-domain service request from
the CNC at the CMI (e.g., between R1 and R3 in Figure 1), can follow
the same procedures, described above for the multi-domain service,
and decide the network configuration to request only at the MPI of
the PNC controlling that domain (e.g., MPI1 of PNC1 in Figure 2).
4.2. Topology Abstractions
Abstraction provides a selective method for representing connectivity
information within a domain. There are multiple methods to abstract
a network topology. This document assumes the abstraction method
defined in [RFC7926]:
Abstraction is the process of applying policy to the available TE
information within a domain, to produce selective information that
represents the potential ability to connect across the domain.
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Thus, abstraction does not necessarily offer all possible
connectivity options, but it presents a general view of potential
connectivity according to the policies that determine how the
domain's administrator wants to allow the domain resources to be
used.
[RFC8453] Provides the context of topology abstraction in the ACTN
architecture and discusses a few alternatives for the abstraction
methods for both packet and optical networks. This is an important
consideration since the choice of the abstraction method impacts
protocol design and the information it carries. According to
[RFC8453], there are three types of topologies:
* White topology: This is a case where the PNC provides the actual
network topology to the MDSC without any hiding or filtering. In
this case, the MDSC has the full knowledge of the underlying
network topology;
* Black topology: The entire domain network is abstracted as a
single virtual node with the access links and inter-domain links
without disclosing any node internal connectivity information;
* Grey topology: This abstraction level is between black topology
and white topology from a granularity point of view.
Each PNC should provide the MDSC a network topology abstraction
hiding the internal details of the physical domain network topology
controlled by the PNC. As described in section 3 of [RFC8453], the
level of abstraction provided by each PNC is based on the PNC
configuration parameters and it is independent of the abstractions
provided by other PNCs. Therefore, it is possible that different
PNCs provides different topology abstractions. The MDSC can operate
on each MPI abstract topology regardless of, and independently from,
the type of abstraction provided by its underlying PNC.
For analyzing how the MDSC can operate on an abstract topology
provided by several PNCs that independently applied different
abstraction policies and therefore provided different types of
abstract topologies, the following assumptions are made for the
reference network in Figure 1:
* PNC1 and PNC2 provide black topology abstractions which expose at
MPI1, and MPI2 respectively, a single virtual node (representing
the whole network domain 1, and domain 2 respectively).
* PNC3 provides a white topology abstraction which exposes at MPI3
all the physical nodes and links within network domain 3.
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The MDSC should be capable of stitching together the abstracted
topologies provided by each PNC to build its view of the multi-
domain network topology. This topology knowledge may require proper
oversight, including the application of local policy, configuration
methods, and the application of a trust model. Methods of how to
manage these aspects are out of scope for this document, but
recomandations are provided in the Security section of this document.
The MDSC can also provide topology abstraction of its view of the
multi-domain network topology at its CMIs depending on the customers'
needs and policies: it can provide different topology abstractions at
different CMIs. Analyzing the topology abstractions provided by the
MDSC to its CMIs is outside the scope of this document.
4.3. Service Configuration
In the following scenarios, it is assumed that the CNC is capable of
requesting connectivity services from the MDSC, for example, to
interconnect IP routers.
The type of connectivity services depends on the type of physical
links (e.g. OTN link, ETH link or SDH link) between the routers and
transport network.
The packet processing inside IP routers, including packet
encapsualation and decapsulation, Ri (PKT -> foo) and Rj (foo ->
PKT), are assumed to be performed by means that are not under the
control of, and not visible to, the MDSC or to the PNCs. Therefore,
these mechanisms are outside the scope of this document.
4.3.1. ODU Transit
The physical links interconnecting the IP routers and the transport
network can be 10G OTN links.
In this case, it is assumed that the physical/optical
interconnections below the ODU layer (up to the OTU2 trail) are pre-
provisioned using mechanisms which are outside the scope of this
document and not exposed at the MPIs between the PNCs and the MDSC.
For simplicity of the description, it is also assumed that these
interfaces are not channelized (i.e., they can only support one
ODU2).
When a 10Gb IP connectivity service between R1 and R8 is needed, an
ODU2 end-to-end connection needs to be created, passing through
transport network nodes S3, S1, S2, S31, S33, S34, S15 and S18, which
belong to different PNC domains (multi-domain service request):
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R1 [(PKT) -> ODU2], S3 [(ODU2]), S1 [(ODU2]), S2 [(ODU2]),
S31 [(ODU2)], S33 [(ODU2)], S34 [(ODU2)],
S15 [(ODU2)], S18 [(ODU2)], R8 [ODU2 -> (PKT)]
The MDSC receives, at the CMI, the request to create an ODU2 transit
service between the access links on S3 and S18, which belong to
different PNC domains (multi-domain service request). The MDSC also
determines the network configuration requests to be sent to its
underlying PNCs, at the MPIs, to coordinate the setup of a multi-
domain ODU2 connection segment between the access links on S3 and
S18.
When a 10Gb IP connectivity service between R1 and R3 is needed, an
ODU2 end-to-end connection needs to be created, passing through
transport network nodes S3, S5 and S6 which belong to the same PNC
domain (single- domain service request):
R1 [(PKT) -> ODU2], S3 [(ODU2)], S5 [(ODU2)], S6 [(ODU2)],
R3 [ODU2 -> (PKT)]
As described in Section 4.1, the mechanisms, used by the CNC at the
CMI, are independent on whether the service request is single-domain
service or multi-domain.
The MDSC can figure out that it needs to setup an ODU2 transit
service between the access links on S3 and S6, which belong to the
same PNC domain (single-domain service request) and it decides the
proper network configuration to request PNC1.
4.3.2. EPL over ODU
The physical links interconnecting the IP routers and the transport
network can be 10G Ethernet physical links (10GE).
In this case, it is assumed that the Ethernet physical interfaces (up
to the MAC layer) are pre-provisioned using mechanisms which are
outside the scope of this document and not exposed at the MPIs
between the PNCs and the MDSC.
When a 10Gb IP connectivity service between R1 and R8 is needed, an
EPL service needs to be created, supported by an ODU2 end-to-end
connection, between transport network nodes S3 and S18, passing
through transport network nodes S1, S2, S31, S33, S34 and S15, which
belong to different PNC domains (multi-domain service request):
R1 [(PKT) -> ETH], S3 [ETH -> (ODU2)], S1 [(ODU2)],
S2 [(ODU2)], S31 [(ODU2)), S33 [(ODU2)], S34 [(ODU2)],
S15 [(ODU2)], S18 [(ODU2) -> ETH], R8 [ETH -> (PKT)]
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The MDSC receives, at the CMI, the request to create an EPL service
between the access links on S3 and S18, which belong to different PNC
domains (multi-domain service request). The MDSC determines the
network configurations to request, at the MPIs, to its underlying
PNCs, to coordinate the setup of an end-to-end ODU2 connection
between the nodes S3 and S8, including the configuration of the
adaptation functions inside these edge nodes, such as S3 [ETH ->
(ODU2)] and S18 [(ODU2) -> ETH].
When a 10Gb IP connection between R1 and R2 is needed, an EPL service
needs to be created, supported by a ODU2 end-to-end connection
between transport network nodes S3 and S6, passing through the
transport network node S5, which belong to the same PNC domain
(single-domain service request):
R1 [(PKT) -> ETH], S3 [ETH -> (PKT)] S5 [(ODU2)],
S6 [(ODU2) -> ETH], R2 [ETH -> (PKT)]
As described in Section 4.1, the mechanisms used by the CNC at the
CMI are independent on whether the service request is single-domain
service or multi-domain.
Based on the assumption above, in this case, the MDSC can figure out
that it needs to setup an EPL service between the access links on S3
and S6, that belong to the same PNC domain (single-domain service
request) and it decides the proper network configuration to request
PNC1.
4.3.3. Transparent Client Services
[ITU-T_G.709] defines mappings of different Transparent Client layers
into ODU. Most of them are used to provide Private Line services
over an OTN transport network supporting a variety of types of
physical access links (e.g., Ethernet, SDH STM-N, Fibre Channel,
InfiniBand, etc.) interconnect the IP routers and the transport
network.
When a 10Gb IP connectivity service between R1 and R8 is needed,
using, for example SDH physical links between the IP routers and the
transport network, an STM-64 Private Line service needs to be
created, supported by a ODU2 end-to-end connection, between transport
network nodes S3 and S18, passing through transport network nodes S1,
S2, S31, S33, S34 and S15, which belong to different PNC domains
(multi-domain service request):
R1 [(PKT) -> STM-64], S3 [STM-64 -> (ODU2)], S1 [(ODU2)],
S2 [(ODU2)], S31 [(ODU2)], S33 [(ODU2)], S34[(ODU2)],
S15 [(ODU2)], S18 [(ODU2) -> STM-64], R8 [STM-64 -> (PKT)]
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As described (Section 4.1) the CNC provides the essential information
to permit the MDSC to compute which type of service is needed, in
this case, an STM-64 Private Line Service between the access links on
S3 and S8, and it also decides the network configurations, including
the configuration of the adaptation functions inside these edge
nodes, such as S3 [STM-64 -> (ODU2)] and S18 [(ODU2) -> STM-64].
When a 10Gb IP connectivity service between R1 and R3 is needed, an
STM-64 Private Line service needs to be created between R1 and R3
(single-domain service request):
R1 [(PKT) -> STM-64], S3[STM-64 -> (ODU2)], S5 [(ODU2)],
S6 [(ODU2) -> STM-64], R3[STM-64 -> (PKT)]
As described in Section 4.1, the mechanisms, used by the CNC at the
CMI, are independent on whether the service request is single-domain
service or multi-domain.
Based on the assumption above, in this case, the MDSC can figure out
that it needs to setup an STM-64 Private Line service between the
access links on S3 and S6, which belong to the same PNC domain
(single-domain service request), and it decides the proper network
configuration to request PNC1.
4.3.4. EVPL over ODU
When the physical links interconnecting the IP routers and the
transport network are Ethernet physical links, it is also possible
that different Ethernet services (e.g., EVPL) can share the same
physical access link using different VLANs.
As described in Section 4.3.2, it is assumed that the Ethernet
physical interfaces (up to the MAC layer) are pre-provisioned.
When two 1Gb IP links between R1 to R2 and between R1 and R8 are
needed, two EVPL services need to be created, supported by two ODU0
end-to-end connections:
R1 [(PKT) -> VLAN], S3 [VLAN -> (ODU0)], S5 [(ODU0)],
S6 [(ODU0) -> VLAN], R2 [VLAN -> (PKT)]
R1 [(PKT) -> VLAN], S3[VLAN -> (ODU0)], S1 [(ODU0)],
S2 [(ODU0)], S31 [(ODU0)], S33 [(ODU0)], S34 [(ODU0)],
S15 [(ODU0)], S18 [(ODU0) -> VLAN], R8[VLAN -> (PKT)]
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It is worth noting that the first EVPL service is required between
access links which belong to the same PNC domain (single-domain
service request) while the second EVPL service is required between
access links which belong to different PNC domains (multi-domain
service request).
Since the two EVPL services share the same Ethernet physical link
between R1 and S3, different VLAN IDs are associated with different
EVPL services: for example, VLAN IDs 10 and 20 respectively.
Based on the assumptions described in Section 4.3.2, the CNC sends a
request to the MDSC, at the CMI, to set up these EVPL services. The
MDSC will determine the network configurations to request to the
underlying PNCs, as described in Section 4.3.2.
4.4. Multi-Function Access Links
Some physical links interconnecting the IP routers and the transport
network can be configured in different modes, e.g., as OTU2 trail or
STM-64 or 10GE physical links.
This configuration can be pre-provisioned by means which are outside
the scope of this document. In this case, these links will appear at
the MPI as links supporting only one mode (depending on how the link
has been pre-provisioned) and will be controlled at the MPI as
discussed in Section 4.3: for example, a 10G multi-function access
link can be pre-provisioned as an OTU2 trail (Section 4.3.1), a 10GE
physical link (Section 4.3.2) or an STM-64 physical link
(Section 4.3.3).
It is also possible not to configure these links a-priori and let the
MDSC (or, in case of a single-domain service request, the PNC) decide
how to configure these links, based on the service configuration.
For example, if the physical link between R1 and S3 is a multi-
functional access link while the physical links between R4 and S6 and
between R8 and S18 are STM-64 and 10GE physical links respectively,
it is possible to configure either an STM-64 Private Line service
between R1 and R4 or an EPL service between R1 and R8.
The traffic flow between R1 and R4 can be summarized as:
R1 [(PKT) -> STM-64], S3 [STM-64 -> (ODU2)], S5 [(ODU2)],
S6 [(ODU2) -> STM-64], R4 [STM-64 -> (PKT)]
The traffic flow between R1 and R8 can be summarized as:
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R1 [(PKT) -> ETH], S3 [ETH -> (ODU2)], S1 [(ODU2)],
S2 [(ODU2)], S31 [(ODU2)), S33 [(ODU2)], S34 [(ODU2)],
S15 [(ODU2)], S18 [(ODU2) -> ETH], R8 [ETH -> (PKT)]
The CNC is capable of requesting, via the CMI, the setup of either an
STM-64 Private Line service, between R1 and R4, or an EPL service,
between R1 and R8.
The MDSC, based on the service being requested, decides the network
configurations to request, at the MPIs, to its underlying PNCs, to
coordinate the setup of an end-to-end ODU2 connection, either between
nodes S3 and S6, or between nodes S3 and S18, including the
configuration of the adaptation functions on these edge nodes, and in
particular whether the multi-function access link between R1 and S3
should operate as an STM-64 or as a 10GE physical link.
Assumptions used in this example, as well as the service scenarios of
Section 4.3, include:
* the R1-S3 and R8-S18 access links will be multi-function access
links, which can be configured as an OTU2 trail or as an STM-64 or
a 10GE physical link;
* the R3-S6 access link will be a multi-function access link which
can be configured as an OTU2 trail or as an STM-64 physical link;
* the R4-S6 access link is pre-provisioned as an STM-64 physical
link;
* all the other access links (and, in particular, the R2-S6 access
links) are pre-provisioned as 10GE physical links, up to the MAC
layer.
4.5. Protection and Restoration Configuration
As described in [RFC4427], recovery can be performed by either
protection switching or restoration mechanisms. This section
describes only services which are protected with linear protection,
considering both end-to-end and segment protection, as defined in
[ITU-T_G.808.1] and [RFC4427]. The description of services using
dynamic restoration is outside the scope of this document.
The MDSC needs to be capable of determining the network
configurations to request different PNCs to coordinate the protection
switching configuration to support protected connectivity services
described in Section 4.3.
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In the service examples described in Section 4.3, switching within
the transport network domain is only performed at the OTN ODU layer.
Therefore, it is also assumed that protection switching within the
transport network also occurs at the OTN ODU layer, using the
mechanisms defined in [ITU-T_G.873.1].
4.5.1. Linear Protection (End-to-End)
To protect the connectivity services described in Section 4.3 from
failures within the OTN multi-domain transport network, the MDSC can
decide to request its underlying PNCs to configure ODU2 linear
protection between the transport network edge nodes (e.g., nodes S3
and S18 for the services setup between R1 and R8).
It is assumed that the OTN linear protection is configured as 1+1
unidirectional protection switching type according to the definition
in [ITU-T_G.808.1] and [ITU-T_G.873.1], as well as in [RFC4427].
In these scenarios, a working transport entity and a protection
transport entity, as defined in [ITU-T_G.808.1], (or a working LSP
and a protection LSP, as defined in [RFC4427]) should be configured
in the data plane.
Two cases can be considered:
* In one case, the working and protection transport entities pass
through the same PNC domains:
Working transport entity: S3, S1, S2,
S31, S33, S34,
S15, S18
Protection transport entity: S3, S4, S8,
S32,
S12, S17, S18
* In another case, the working and protection transport entities can
pass through different PNC domains:
Working transport entity: S3, S5, S7,
S11, S12, S17, S18
Protection transport entity: S3, S1, S2,
S31, S33, S34,
S15, S18
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The PNCs should be capable of reporting to the MDSC which, is the
active transport entity, as defined in [ITU-T_G.808.1], in the data
plane.
Given the fast dynamic of protection switching operations in the data
plane (e.g., 50ms switching time), this reporting is not expected to
be in real-time.
It is also worth noting that with unidirectional protection
switching, e.g., 1+1 unidirectional protection switching, the active
transport entity may be different in the two directions.
4.5.2. Segmented Protection
To protect the connectivity services defined in Section 4.3 from
failures within the OTN multi-domain transport network, the MDSC can
decide to request its underlying PNCs to configure ODU2 linear
protection between the edge nodes of each domain.
For example, the MDSC can request PNC1 to configure linear protection
between its edge nodes S3 and S2:
Working transport entity: S3, S1, S2
Protection transport entity: S3, S4, S8, S2
MDSC can also request PNC2 to configure linear protection between
its edge nodes S15 and S18:
Working transport entity: S15, S18
Protection transport entity: S15, S12, S17, S18
MDSC can also request PNC3 to configure linear protection between its
edge nodes S31 and S34:
Working transport entity: S31, S33, S34
Protection transport entity: S31, S32, S34
4.6. Event Notifications and Alarms
To realize the three functions of topology update, service update,
and restoration, the following notification types need to be
supported:
1. Object create
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2. Object delete
3. Object state change
4. Alarm
There are three types of topology abstraction types defined in
Section 4.2, and the notifications should also be abstracted. The
PNC and MDSC should coordinate together to determine the notification
policy. This will include information such as when an intra-domain
alarm occurred. The PNC may not report the alarm, but it should
provide notification of the service state change to the MDSC.
Detailed analysis and methods of how event alarms are triggered,
managed and propagated are outside the scope of this document.
4.7. Path Computation with Constraints
It is possible to define constraints to be taken into account during
path computation procedures (e.g., Include Route Object (IRO) and
Exclude Route Object (XRO) [RFC5521]).
For example, the CNC can request, at the CMI, an ODU transit service,
as described in Section 4.3.1, between R1 and R8 with the constraint
to pass through the link from S2 to S31 (IRO), such that a qualified
path could be:
R1 [(PKT) -> ODU2], S3 [(ODU2]), S1 [(ODU2]), S2 [(ODU2]),
S31 [(ODU2)], S33 [(ODU2)], S34 [(ODU2)],
S15 [(ODU2)], S18 [(ODU2)], R8 [ODU2 -> (PKT)]
If the CNC instead requested to pass through the link from S8 to S12,
then the above path would not be qualified, while the following would
be:
R1 [(PKT) -> ODU2], S3[(ODU2]), S1 [(ODU2]), S2[(ODU2]),
S8 [(ODU2]), S12[(ODU2]), S15 [(ODU2]), S18[(ODU2]), R8 [ODU2 ->
(PKT)]
The mechanisms used by the CNC to provide path constraints at the
CMI, are outside the scope of this document. It is assumed that the
MDSC can satisfy these constraints and take them into account in its
path computation procedures (which would decide at least which
domains and inter-domain links) and in the path computation
constraints to provide to its underlying PNCs, to be taken into
account in the path computation procedures implemented by the PNCs
(with a more detailed view of topology).
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Further detailed analysis is outside the scope of this document.
5. YANG Model Analysis
This section analyses how the IETF YANG models can be used at the
MPIs, between the MDSC and the PNCs, to support the scenarios
described in Section 4.
The YANG models described in [ACTN-YANG] are assumed to be used at
the MPI.
Section 5.1 describes the different topology abstractions provided to
the MDSC by each PNC via its own MPI.
Section 5.2 describes how the MDSC can request different PNCs, via
their own MPIs, the network configuration needed to setup the
different services described in Section 4.3.
Section 5.3 describes how the protection scenarios can be deployed,
including end-to-end protection and segment protection, for both
intra-domain and inter-domain scenario.
5.1. YANG Models for Topology Abstraction
This section analyses how each PNC can report its respective abstract
topology to the MDSC, as described in Section 4.2, using the Topology
YANG models, defined in [RFC8345], with the TE Topology YANG
augmentations, provided in [RFC8795], and the OTN technology-specific
YANG augmentations, defined in [OTN-TOPO] or the Ethernet client
technology-specific YANG augmentations, defined in [CLIENT-TOPO].
As described in Section 4.1, the OTU4 trails on inter-domain and
intra-domain physical links are pre-provisioned and, therefore, not
exposed at the MPIs. Only the TE Links they support can be exposed
at the MPI, depending on the topology abstraction performed by the
PNC.
The access links can be multi-function access links, as described in
Section 4.4.
As described in Section 4.1, each physical access link has a
dedicated set of ODU termination and adaptation resources.
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The [OTN-TOPO] model allows reporting within the OTN abstract
topology also the access links which are capable of supporting the
transparent client layers, defined in Section 4.3.3 and in
[CLIENT-SIGNAL]. These links can also be multi-function access links
that can be configured as transparent client physical links (e.g.,
STM-64 physical link) or as an OTUk trail.
In order to support the EPL and EVPL services, described in
Section 4.3.2 and Section 4.3.4, the access links, which are capable
of being configured as Ethernet physical links, are reported by each
PNC within its respective Ethernet abstract topology, using the
Topology YANG models, defined in [RFC8345], with the TE Topology YANG
augmentations, defined in [RFC8795], and the Ethernet client
technology-specific YANG augmentations, defined in [CLIENT-TOPO].
These links can also be multi-function access links that can be
configured as an Ethernet physical link, an OTUk trail, or as a
transparent client physical links (e.g., STM-64 physical link). In
this case, these physical access links are represented in both the
OTN and Ethernet abstract topologies.
The PNC reports the capabilities of the access or inter-domain link
ends it can control. It is the MDSC responsibility to request
configuration of these links matching the capabilities of both link
ends.
It is worth noting that in the network scenarios analyzed in this
document (where switching is performed only at the ODU layer), the
Ethernet abstract topologies reported by the PNCs describes only the
Ethernet client access links: no Ethernet TE switching capabilities
are reported in these Ethernet abstract topologies, to report that
the underlying networt domain is not capable supporting Ethernet TE
Tunnels/LSPs.
5.1.1. Domain 1 Black Topology Abstraction
PNC1 provides the required black topology abstraction, as described
in Section 4.2. It exposes at MPI1 to the MDSC, two TE Topology
instances with only one TE node each.
The first TE Topology instance reports the domain 1 OTN abstract
topology view (MPI1 OTN Topology), using the OTN technology-specific
augmentations [OTN-TOPO], with only one abstract TE node (i.e., AN1)
moreover, only inter-domain and access abstract TE links (which
represent the inter-domain physical links and the access physical
links that can support ODU, or transparent client layers, both), as
shown in Figure 3 below.
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...................................
: :
: +-----------------+ :
: | | :
(R1)- - --------| |-------- - -(S31)
: AN1-1 | | AN1-7 :
: | | :
(R3)- - --------| | :
: AN1-2 | AN1 | :
: | | :
(R4)- - --------| |-------- - -(S32)
: AN1-3 | | AN1-6 :
: | | :
: +-----------------+ :
: | | :
: AN1-4 | | AN1-5 :
:..........|..........|...........:
| |
(S11) (S12)
Figure 3: OTN Abstract Topology exposed at MPI1 (MPI1 OTN Topology)
The second TE Topology instance reports the domain 1 Ethernet
abstract topology view (MPI1 ETH Topology), using the Ethernet
technology-specific augmentations [CLIENT-TOPO], with only one
abstract TE node (i.e., AN1) and only access abstract TE links (which
represent the access physical links which can support Ethernet client
layers), as shown in Figure 4 below.
...................................
: :
: +-----------------+ :
: | | :
(R1)- - --------| | :
: AN1-1 | | :
: | | :
(R2)- - --------| | :
: AN1-8 | AN1 | :
: | | :
: | | :
: | | :
: | | :
: +-----------------+ :
: :
:.................................:
Figure 4: ETH Abstract Topology exposed at MPI1 (MPI1 ETH Topology)
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The OTU4 trails on the inter-domain physical links (e.g., the link
between S2 and S31) are pre-provisioned and exposed as external TE
Links, within the MPI1 OTN topology (e.g., the external TE Link
terminating on AN1-7 TE Link Termination Point (LTP) abstracting the
OTU4 trail between S2 and S31).
The PNC1 exports at MPI1 the following external TE Links, within the
MPI1 OTN topology, representing the multi-function access links under
its control:
* two abstract TE Links, terminating on LTP AN1-1 and AN1-2
respectively, abstracting the physical access link between S3 and
R1 and the access link between S6 and R3 respectively, reporting
that they can support STM-64 client signals as well as ODU2
connections;
* one abstract TE Link, terminating on LTP AN1-3, abstracting the
physical access link between S6 and R4, reporting that it can
support STM-64 client signals but no ODU2 connections.
The information about the 10GE access link between S6 and R2 as well
as the fact that the access link between S3 and R1 can also be
configured as a 10GE link cannot be exposed by PNC1 within the MPI1
OTN topology.
Therefore, PNC1 exports at MPI1, within the MPI1 ETH topology, two
abstract TE Links, terminating on LTP AN1-1 and AN1-8 respectively,
abstracting the physical access link between S3 and R1 and the access
link between S6 and R2 respectively, reporting that they can support
Ethernet client signal with port-based and VLAN-based
classifications.
PNC1 should expose at MPI1 also the ODU termination and adaptation
resources that are available to carry client signals (e.g., Ethernet
or STM-N) over OTN. This information is reported by the Tunnel
Termination Points (TTPs) within the MPI1 OTN Topology.
In particular, PNC1 will report, within the MPI1 OTN Topology, one
TTP for each access link (i.e., AN1-1, AN1-2, AN1-3 and AN1-8) and
will assign a transition link or an inter-layer lock identifier,
which is unique across all the TE Topologies PNC1 is exposing at
MPI1, to each TTP and access link's LTP pair.
For simplicity purposes, this document assigns the same number to the
LTP-ID, TTP-ID and ILL-ID that corresponds to the same access link
(i.e., 1, 2, 3 and 8 respectively for the LTP, TTP and Inter-Layer
Lock (IIL) corresponding with the access links AN1-1, AN1-2, AN1-3
and AN1-8).
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The PNC1 native topology would represent the physical network
topology of the domain controlled by the PNC, as shown in Figure 5.
..................................
: :
: Physical Topology @ PNC1 :
: :
: +----+ +----+ :
: | |S1-1 | |S2-3:
: | S1 |--------| S2 |----- - -(S31)
: +----+ S2-1+----+ :
: S1-2/ |S2-2 :
: S3-4/ | :
: +----+ +----+ | :
: | |3 1| | | :
(R1)- - -----| S3 |---| S4 | | :
:S3-1+----+ +----+ | :
: S3-2 \ \S4-2 | :
: \S5-1 \ | :
: +----+ \ | :
: | | \S8-2| :
: | S5 | \ | :
: +----+ \ |S8-1 :
(R2)- - ------ 2/ \3 \ | :
:S6-1 \ /5 \1 \| :
: +----+ +----+ +----+ :
: | | | | | |S8-5:
(R3)- - -----| S6 |---| S7 |---| S8 |----- - -(S32)
:S6-2+----+4 2+----+4 3+----+ :
: / | | :
(R3)- - ------ S7-3 | | S8-4 :
:S6-3 | | :
:...............|........|.......:
| |
(S11) (S12)
Figure 5: Physical Topology controlled by PNC1
The PNC1 native topology is not exposed, and therefore it is the
PNC's responsibility to abstract the whole domain physical topology
as a single TE node and to maintain a mapping between the LTPs
exposed at MPI abstract topologies and the associated physical
interfaces controlled by the PNC:
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Physical Interface OTN Topology LTP ETH Topology LTP
(Figure 5) (Figure 3) (Figure 4)
S2-3 AN1-7
S3-1 AN1-1 AN1-1
S6-1 AN1-8
S6-2 AN1-2
S6-3 AN1-3
S7-3 AN1-4
S8-4 AN1-5
S8-5 AN1-6
Appendix B.1.1 provides the detailed JSON code example ("mpi1-otn-
topology.json") describing how the MPI1 ODU Topology is reported by
the PNC1, using the [RFC8345], [RFC8795] and [OTN-TOPO] YANG models,
at MPI1.
Appendix B.1.2 provides the detailed JSON code example ("mpi1-eth-
topology.json") describing how the MPI1 ETH Topology is reported by
the PNC1, using the [RFC8345], [RFC8795] and [CLIENT-TOPO] YANG
models, at MPI1.
It is worth noting that this JSON code example does not provide all
the attributes defined in the relevant YANG models, including:
* YANG attributes that are outside the scope of this document are
not shown;
* The attributes describing the set of label values that are
available at the inter-domain links (label-restriction container)
are also not shown to simplify the JSON code example;
* The comments describing the rationale for not including some
attributes in this JSON code example even if in the scope of this
document are identified with the prefix "// comment" and included
only in the first object instance (e.g., in the Access Link from
the AN1-1 description or in the AN1-1 LTP description).
5.1.2. Domain 2 Black Topology Abstraction
PNC2 provides the required black topology abstraction, as described
in Section 4.2, to expose to the MDSC, at MPI2, two TE Topology
instances with only one TE node each:
* the first instance reports the domain 2 OTN abstract topology view
(MPI2 OTN Topology), with only one abstract node (i.e., AN2) and
only inter-domain and access abstract TE links (which represent
the inter-domain physical links and the access physical links that
can support ODU, transparent client layers, or both);
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* the instance reports the domain 2 Ethernet abstract topology view
(MPI2 ETH Topology), with only one abstract TE node (i.e., AN2)
and only access abstract TE links (which represent the access
physical links which can support Ethernet client layers).
PNC2 also reports the ODU termination and adaptation resources which
are available to carry client signals (e.g., Ethernet or STM-N) over
OTN in the TTPs within the MPI2 OTN Topology.
In particular, PNC2 reports in both the MPI2 OTN Topology and MPI2
ETH Topology an access link that abstracts the multi-function
physical access link between S18 and R8, and terminates on the AN2-1
LTP that corresponds to the S18-3 physical interface, within the PNC2
native topology. It also reports in the MPI2 ODU Topology an AN2-1
TTP which abstracts the ODU termination and adaptation resources
dedicated to this physical access link and the inter-layer lock
between the AN2-1 TTP, and the AN2-1 LTPs reported within the MPI2
OTN Topology and the MPI2 ETH Topology.
5.1.3. Domain 3 White Topology Abstraction
PNC3 provides the required white topology abstraction, as described
in Section 4.2, to expose to the MDSC, at MPI3, two TE Topology
instances with multiple TE nodes, one for each physical node:
* the first instance reports the domain 3 OTN topology view (MPI3
OTN Topology), with four TE nodes, which represent the four
physical nodes (i.e. S31, S32, S33 and S34), and abstract TE
links, which represent the inter-domain and internal physical
links;
* the second instance reports the domain 3 Ethernet abstract
topology view (MPI3 ETH Topology), with only two TE nodes, which
represent the two edge physical nodes (i.e., S31 and S33) and only
the two access TE links which represent the access physical links.
PNC3 also reports the ODU termination and adaptation resources which
are available to carry client signals (e.g., Ethernet or STM-N) over
OTN in the TTPs within the MPI3 OTN Topology.
5.1.4. Multi-domain Topology Merging
MDSC does not have any knowledge of the topologies of each domain
until each PNC reports its abstract topologies, so the MDSC needs to
merge these abstract topologies, provided by different PNCs, to build
its topology view of the multi-domain network (MDSC multi-domain
native topology), as described in section 4.3 of [RFC8795].
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The topology of each domain may be in an abstracted shape (refer to
section 5.2 of [RFC8453] for a different level of abstraction), while
the inter-domain link information must be complete and fully
configured by the MDSC.
The inter-domain link information is reported to the MDSC by the two
PNCs, controlling the two ends of the inter-domain link.
The MDSC needs to know how to merge these inter-domain links. One
possibility is to use the plug-id information, defined in [RFC8795]:
two inter-domain TE links, within two different MPI abstract
topologies, terminating on two LTPs reporting the same plug-id value
can be merged as a single intra-domain link, within any MDSC native
topology.
The value of the reported plug-id information can be either assigned
by a central network authority and configured within the two PNC
domains. Alternatively, it may be discovered using an automatic
discovery mechanisms (e.g., LMP-based, as defined in [RFC6898]).
In case the plug-id values are assigned by a central authority, it is
under the central authority's responsibility to assign unique values.
In case the plug-id values are automatically discovered, the
information discovered by the automatic discovery mechanisms needs to
be encoded as a bit string within the plug-id value. This encoding
is implementation-specific, but the encoding rules need to be
consistent across all the PNCs.
In case of co-existence within the same network of multiple sources
for the plug-id (e.g., central authority and automatic discovery or
even different automatic discovery mechanisms), it is needed that the
plug-id namespace is partitioned to avoid that different sources
assign the same plug-id value to different inter-domain links. Also,
the encoding of the plug-id namespace within the plug-id value is
implementation-specific and will need to be consistent across all the
PNCs.
This document assumes that the plug-id is assigned by a central
authority, with the first octet set to 0x00 to represent the central
authority namespace. The configuration method used, within each PNC
domain, are outside the scope of this document.
For example, this document assumes that the following plug-id values
are assigned, by administrative configuration, to the inter-domain
links shown in Figure 1:
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Inter-Domain Link Plug-ID Value
S2-S31 0x000231
S7-S11 0x000711
S8-S12 0x000812
S8-S32 0x000832
S12-S32 0x001232
S15-S34 0x001534
Based on the plug-id values, the MDSC can merge the abstract
topologies exposed by the underlying PNCs, as described in
Section 5.1.1, Section 5.1.2 and Section 5.1.3 above, into its multi-
domain native TE topology, as shown in Figure 6.
........................
: :
: Network domain 1 : .............
: Black Topology : : :
: Abstraction : : Network :
: AN1-1 : : domain 3 :
(R1)- - ----------+ : : (White) :
: \ +--------------+ :
(R2)- - ---------+ + / : : \ :
: \| / : : \ :
(R3)- - --------- AN1 --+ : : S31 ---- - (R5)
: /|\ \ : : / \ : :
(R4)- - ---------+ | \ +--------- S32 S33 - - (R6)
: | \ : :/ \ / :
: | +---+ : / S34 :
:..........|.......|...: /: / :
| | / :../........:
| | / /
...........|.......|.../..../....
: | | / / :
: Network | + / / :
: domain 2 | / / / :
: | / / / :
: | + / +--+ :
: | |/ / :
: Black +--- AN2 ------------- - -(R7)
: Topology | | AN2-1 :
: Abstraction | +-------------- - -(R8)
: | :
: +---------------- - -(R9)
: :
:...............................:
Figure 6: Multi-domain Abstract Topology controlled by an MDSC
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5.2. YANG Models for Service Configuration
This section analyses how the MDSC can request the different PNCs to
setup different multi-domains services, as described in Section 4.3,
using the TE Tunnel YANG model, defined in [TE-TUNNEL], with the OTN
technology-specific augmentations, defined in [OTN-TUNNEL] with the
client service YANG model defined in [CLIENT-SIGNAL].
The service configuration procedure is assumed to be initiated (step
1 in Figure 7) at the CMI from CNC to MDSC. Analysis of the CMI
models (e.g., L1CSM, L2SM, VN) are outside the scope of this
document, but it is assumed that the CMI YANG models provide all the
information that allows the MDSC to understand that it needs to
coordinate the setup of a multi-domain ODU data plane connection
(which can be either an end-to-end connection or a segment
connection) and, when needed, also the configuration of the
adaptation functions in the edge nodes belonging to different
domains.
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|
| {1}
V
----------------
| {2} |
| {3} MDSC |
| |
----------------
^ ^ ^
{3.1} | | |
+---------+ |{3.2} |
| | +----------+
| V |
| ---------- |{3.3}
| | PNC2 | |
| ---------- |
| ^ |
V | {4.2} |
---------- V |
| PNC1 | ----- V
---------- (Network) ----------
^ ( Domain 2) | PNC3 |
| {4.1} ( _) ----------
V ( ) ^
----- C==========D | {4.3}
(Network) / ( ) \ V
( Domain 1) / ----- \ -----
( )/ \ (Network)
A===========B \ ( Domain 3)
/ ( ) \( )
AP-1 ( ) X===========Z
----- ( ) \
( ) AP-2
-----
Figure 7: Multi-domain Service Setup
As an example, the objective in this section is to configure a
connectivity service between R1 and R8, such as one of the services
described in Section 4.3. The inter-domain path is assumed to be R1
<-> S3 <-> S1 <-> S2 <-> S31 <-> S33 <-> S34 <->S15 <-> S18 <-> R8
(see the physical topology in Figure 1).
According to the different client signal types, different adaptations
can be required to be configured at the edge nodes (i.e., S3 and
S18).
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After receiving such request, MDSC determines the domain sequence,
i.e., domain 1 <-> domain 3 <-> domain 2, with corresponding PNCs and
the inter-domain links (step 2 in Figure 7).
As described in [PATH-COMPUTE], the domain sequence can be determined
by running the MDSC own path computation on the MDSC native topology,
defined in Section 5.1.4, if and only if the MDSC has enough topology
information. Otherwise, the MDSC can send path computation requests
to the different PNCs (steps 2.1, 2.2 and 2.3 in Figure 7) and use
this information to determine the optimal path on its internal
topology and, therefore, the domain sequence.
The MDSC will then decompose the tunnel request into a few TE tunnel
segments and request different PNCs to setup each intra-domain TE
tunnel segment (steps 3, 3.1, 3.2 and 3.3 in Figure 7).
The MDSC will take care of the configuration of both the intra-
domain TE tunnel segments and inter-domain TE tunnel hand-off via
corresponding MPI (using the TE tunnel YANG model defined in
[TE-TUNNEL] and the OTN tunnel YANG model augmentations defined in
[OTN-TUNNEL]) through all the PNCs controlling the domains selected
during path computation. More specifically, for the inter-domain TE
tunnel hand-off, taking into account that the inter-domain links are
all OTN links, the list of timeslots and the TPN value assigned to
that ODUk connection at the inter-domain link needs to be configured
by the MDSC.
The configuration of the timeslots and the TPN value used by the ODU2
connection on the internal links within a PNC domain (i.e., on the
internal links within domain1) is outside the scope of this document,
since it is a matter of the PNC domain internal implementation.
However, the configuration of the timeslots used by the ODU2
connection at the transport network domain boundaries (e.g., on the
inter-domain links) needs to take into account the timeslots
available on physical nodes belonging to different PNC domains (e.g.,
on node S2 within PNC1 domain and node S31 within PNC3 domain). Each
PNC provides to the MDSC, at the MPI, the list of available timeslots
on the inter-domain links using the TE Topology
YANG model and OTN Topology augmentation. The TE Topology YANG model
in [RFC8795] is being updated to report the label set information.
See section 1.7 of [TE-TUTORIAL] for more details.
The MDSC, when coordinating the setup of a multi-domain ODU
connection, also configures the data plane resources (i.e., the list
of timeslots and the TPN) to be used on the inter-domain links. The
MDSC can know the timeslots which are available on the physical OTN
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nodes terminating the inter-domain links (e.g., S2 and S31) from the
OTN Topology information exposed, at the MPIs, by the PNCs
controlling the OTN physical nodes (e.g., PNC1 and PNC3 controlling
the physical nodes S2 and S31, respectively).
In any case, the access link configuration is done only on the PNCs
that control the access links (e.g., PNC-1 and PNC-3) and not on the
PNCs of transit domain(s) (e.g., PNC-2). An access link will be
configured by MDSC after the OTN tunnel is set up.
Access configuration will vary and will be dependent on each type of
service. Further discussion and examples are provided in the
following sub-sections.
5.2.1. ODU Transit Service
In this scenario, described in Section 4.3.1, the physical access
links are configured as 10G OTN links and, as described in
Section 5.1, reported by each PNC as TE Links within the OTN abstract
topologies they expose to the MDSC.
When an IP link, between R1 and R8 is needed, the CNC requests, at
the CMI, the MDSC to setup an ODU transit service.
From its native topology, shown in Figure 6, the MDSC understands, by
means which are outside the scope of this document, that R1 is
attached to the access link terminating on AN1-1 LTP in the MPI1 OTN
Abstract Topology (Figure 3), exposed by PNC1, and that R8 is
attached to the access link terminating on AN2-1 LTP in the MPI2
Abstract Topology, exposed by PNC2.
MDSC then performs multi-domain path computation (step 2 in Figure 7)
and requests PNC1, PNC2 and PNC3, at MPI1, MPI2 and MPI3
respectively, to setup ODU2 (Transit Segment) Tunnels within the OTN
Abstract Topologies they expose (MPI1 OTN Abstract Topology, MPI2 OTN
Abstract Topology and MPI3 OTN Abstract Topology, respectively).
The MDSC requests, at MPI1, PNC1 to setup an ODU2 (Transit Segment)
Tunnel with one primary path between AN-1 and AN1-7 LTPs, within the
MPI1 OTN Abstract Topology (Figure 3), using the TE Tunnel YANG
model, defined in [TE-TUNNEL], with the OTN technology-specific
augmentations, defined in [OTN-TUNNEL]:
* Source and Destination TTPs are not specified (since it is a
Transit Tunnel): i.e., the source, src-tp-id, destination and dst-
tp-id attributes of the TE tunnel instance are empty
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* Ingress and egress points are indicated in the route-object-
include-exclude list of the explicit-route-objects of the primary
path:
- The first element references the access link terminating on
AN1-1 LTP
- The last two element reference respectively the inter-domain
link terminating on AN1-7 LTP and the data plane resources
(i.e., the list of timeslots and the TPN) used by the ODU2
connection over that link.
Appendix B.2.1 provides the detailed JSON code ("mpi1-odu2-service-
config.json") describing how the setup of this ODU2 (Transit Segment)
Tunnel can be requested by the MDSC, using the [TE-TUNNEL] and
[OTN-TUNNEL] YANG models at MPI1.
PNC1 knows, as described in the mapping table in Section 5.1.1, that
AN-1 and AN1-7 LTPs within the MPI1 OTN Abstract Topology it exposes
at MPI1 correspond to the S3-1 and S2-3 LTPs, respectively, within
its native topology. Therefore it performs path computation for an
ODU2 connection between these LTPs within its native topology, and
sets up the ODU2 cross-connections within the physical nodes S3, S1
and S2.
Since the R1-S3 access link is a multi-function access link, PNC1
also configures the OTU2 trail before setting up the ODU2 cross-
connection in node S3.
As part of the OUD2 cross-connection configuration in node S2, PNC1
configures the data plane resources (i.e., the list of timeslots and
the TPN), to be used by this ODU2 connection on the S2-S31 inter-
domain link, as requested by the MDSC.
Following similar requests from MDSC to setup ODU2 (Transit Segment)
Tunnels within the OTN Abstract Topologies they expose, PNC2 then
sets up ODU2 cross-connections on nodes S31 and S33 while PNC3 sets
up ODU2 cross-connections on nodes S15 and S18. PNC2 also configures
the OTU2 trail on the S18-R8 multi-function access link.
5.2.1.1. Single Domain Example
To setup an ODU2 end-to-end connection, supporting an IP link,
between R1 and R3, the CNC requests, at the CMI, the MDSC to setup an
ODU transit service.
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Following the procedures described in Section 5.2.1, MDSC requests
only PCN1 to setup the ODU2 (Transit Segment) Tunnel between the
access links terminating on AN-1 and AN1-2 LTPs within the MPI1
Abstract Topology and PNC1 sets up ODU2 cross-connections on nodes
S3, S5 and S6. PNC1 also configures the OTU2 trails on the R1-S3 and
R3-S6 multi-function access links.
5.2.2. EPL over ODU Service
In this scenario, described in Section 4.3.2, the access links are
configured as 10GE Links and, as described in Section 5.1, reported
by each PNC as TE Links within the ETH abstract topologies they
expose to the MDSC.
When this IP link, between R1 and R8, is needed, the CNC requests, at
the CMI, the MDSC to setup an EPL service.
From its native topology, shown in Figure 6, the MDSC understands, by
means which are outside the scope of this document, that R1 is
attached to the access link terminating on AN1-1 LTP in the MPI1 ETH
Abstract Topology, exposed by PNC1, and that R8 is attached to the
access link terminating on AN2-1 LTP in the MPI2 ETH Abstract
Topology, exposed by PNC2.
As described in Section 5.1.1 and Section 5.1.2:
* the AN1-1 LTP, within the MPI1 ETH Abstract Topology, and the
AN1-1 TTP, within the MPI1 OTN Abstract Topology, have the same
IIL identifier (within the scope of MPI1);
* the AN2-1 LTP, within the MPI2 ETH Abstract Topology, and the
AN2-1 TTP, within the MPI2 OTN Abstract Topology, have the same
IIL identifier (within the scope of MPI2).
Therefore, the MDSC also understands that it needs to coordinate the
setup of a multi-domain ODU2 Tunnel between AN1-1 and AN2-1 TTPs,
abstracting the ODU termination and adaptation resources on S3-1 and
S18-3 physical interfaces, within the OTN Abstract Topologies exposed
by PNC1 and PNC2, respectively.
MDSC then performs multi-domain path computation (step 2 in Figure 7)
and then requests:
* PNC1, at MPI1, to setup an ODU2 (Head Segment) Tunnel within the
MPI1 OTN Abstract Topology;
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* PNC1, at MPI1, to steer the Ethernet client traffic from/to AN1-1
LTP, within the MPI1 ETH Abstract Topology, thought that ODU2
(Head Segment) Tunnel;
* PNC3, at MPI3, to setup an ODU2 (Transit Segment) Tunnel within
the MPI3 OTN Abstract Topology;
* PNC2, at MPI2, to setup ODU2 (Tail Segment) Tunnel within the MPI2
OTN Abstract Topology;
* PNC2, at MPI2, to steer the Ethernet client traffic to/from AN2-1
LTP, within the MPI2 ETH Abstract Topology, through that ODU2
(Tail Segment) Tunnel.
MDSC requests, at MPI1, PNC1 to setup an ODU2 (Head Segment) Tunnel
with one primary path between the AN1-1 TTP and AN1-7 LTP, within the
MPI1 OTN Abstract Topology (Figure 3), using the TE Tunnel YANG
model, defined in [TE-TUNNEL], with the OTN technology-specific
augmentations, defined in [OTN-TUNNEL]:
* Only the Source TTP (i.e., AN1 TE-Node and AN1-1 TTP) is specified
(since it is a Head Segment Tunnel): therefore the Destination TTP
is not specified
* The egress point in indicated in the route-object-include-exclude
list of the explicit-route-objects of the primary path:
- The last two element reference respectively the inter-domain
link terminating on AN1-7 LTP and the data plane resources
(i.e., the list of timeslots and the TPN) used by the ODU2
connection over that link.
Since there is not enough information about which client traffic
should be steered to the OTN Tunnel, the ODU2 (Head Segment) Tunnel
is setup with the administrative auto state, as defined in
[TE-TUNNEL].
Appendix B.2.2 provides the detailed JSON code ("mpi1-odu2-tunnel-
config.json") describing how the setup of this ODU2 (Head Segment)
Tunnel can be requested by the MDSC, using the [TE-TUNNEL] and
[OTN-TUNNEL] YANG models at MPI1.
MDSC requests, at MPI1, PNC1 to steer the Ethernet client traffic
from/to AN1-2 LTP, within the MPI1 ETH Abstract Topology (Figure 4),
thought the MPI1 ODU2 (Head Segment) Tunnel, using the Ethernet
Client YANG model, defined in [CLIENT-SIGNAL].
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Appendix B.2.3 provides the detailed JSON code ("mpi1-epl-service-
config.json") describing how the setup of this EPL service using the
ODU2 Tunnel can be requested by the MDSC, using the [CLIENT-SIGNAL]
YANG model at MPI1.
PNC1 knows, as described in the table in Section 5.1.1, that the
AN1-1 TTP and the AN1-7 LTP, within the MPI1 OTN Abstract Topology it
exposes at MPI1, correspond to S3-1 TTP and S2-3 LTP, respectively,
within its native topology. Therefore it performs path computation,
for an ODU2 connection between S3-1 TTP and S2-3 LTP within its
native topology, and sets up the ODU2 cross-connections within the
physical nodes S3, S1 and S2, as shown in Section 4.3.2.
As part of the OUD2 cross-connection configuration in node S2, PNC1
configures the data plane resources (i.e., the list of timeslots and
the TPN), to be used by this ODU2 connection on the S2-S31 inter-
domain link, as requested by the MDSC.
After the configuration of the ODU2 cross-connection in node S3, PNC1
also configures the [ETH -> (ODU)] and [(ODU2) -> ETH] adaptation
functions, within node S3, as shown in Section 4.3.2.
Since the R1-S3 access link is a multi-function access link, PNC1
also configures the 10GE link before this step.
Following similar requests from MDSC to setup ODU2 (Segment) Tunnels
within the OTN Abstract Topologies, they expose as well as the
steering of the Ethernet client traffic, PNC3 then sets up ODU2
cross-connections on nodes S31 and S33 while PNC2 sets up ODU2 cross-
connections on nodes S15 and S18 as well as the [ETH -> (ODU2)] and
[(ODU2) -> ETH] adaptation functions in node S18, as shown in
Section 4.3.2. PNC2 also configures the 10GE link on the S18-R8
multi-function access link.
5.2.2.1. Single Domain Example
When this IP link, between R1 and R2, is needed, the CNC requests, at
the CMI, the MDSC to setup an EPL service.
Following the procedures described in Section 5.2.2, the MDSC
requests PCN1 to:
* Setup an ODU2 (end-to-end) Tunnel between the AN1-1 and AN1-2
TTPs, abstracting S3-1 and S6-1 TTPs, within the MPI1 OTN Abstract
Topology exposed by PNC1 at MPI1;
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* Steer the Ethernet client traffic between the AN1-1 and AN1-8
LTPs, exposed by PNC1 within MPI1 ETH Abstract Topology, through
that ODU2 (end-to-end) Tunnel.
Then PNC1 sets up ODU2 cross-connections on nodes S3, S5 and S6 as
well as the [ETH -> (ODU)] and [(ODU2) -> ETH] adaptation functions
in nodes S3 and S6, as shown in Section 4.3.2. PNC1 also configures
the 10GE link on the R1-S3 multi-function access link (the R2-S6
access link has been pre-provisioned as a 10GE link, as described in
Section 4.4).
5.2.3. Other OTN Client Services
In this scenario, described in Section 4.3.3, the access links are
configured as STM-64 links and, as described in Section 5.1, reported
by each PNC as TE Links within the OTN Abstract Topologies they
expose to the MDSC.
The CNC requests, at the CMI, MDSC to setup an STM-64 Private Line
service between R1 and R8.
Following similar procedures as described in Section 5.2.2, the MDSC
understands that:
* R1 is attached to the access link terminating on AN1-1 LTP in the
MPI1 OTN Abstract Topology, exposed by PNC1, and that R8 is
attached to the access link terminating on AN2-1 LTP in the MPI2
OTN Abstract Topology, exposed by PNC2;
* it needs to coordinate the setup of a multi-domain ODU2 Tunnel
between the AN1-1 and AN2-1 TTPs, abstracting the ODU termination
and adaptation resources on S3-1 and S18-3 physical interfaces,
within the OTN Abstract Topologies exposed by PNC1 and PNC2,
respectively.
The MDSC then performs multi-domain path computation (step 2 in
Figure 7) and then requests:
* PNC1, at MPI1, to setup an ODU2 (Head Segment) Tunnel within the
MPI1 OTN Abstract Topology;
* PNC1, at MPI1, to steer the STM-64 transparent client traffic
from/to AN1-1 LTP, within the MPI1 OTN Abstract Topology, thought
that ODU2 (Head Segment) Tunnel;
* PNC3, at MPI3, to setup an ODU2 (Transit Segment) Tunnel within
the MPI3 OTN Abstract Topology;
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* PNC2, at MPI2, to setup ODU2 (Tail Segment) Tunnel within the MPI2
OTN Abstract Topology;
* PNC2, at MPI2, to steer the STM-64 transparent client traffic to/
from AN2-1 LTP, within the MPI2 ETH Abstract Topology, through
that ODU2 (Tail Segment) Tunnel.
PNC1, PNC2 and PNC3 then sets up the ODU2 cross-connections within
the physical nodes S3, S1, S2, S31, S33, S15 and S18 as well as the
[STM-64 -> (ODU)] and [(ODU2) -> STM-64] adaptation functions in
nodes S3 and S18, as shown in Section 4.3.3. PNC1 and PNC2 also
configure the STM-64 links on the R1-S3 and R8-S18 multi-function
access links, respectively.
5.2.3.1. Single Domain Example
When an IP link, between R1 and R3, is needed, the CNC requests, at
the CMI, the MDSC to setup an STM-64 Private Line service.
The MDSC and PNC1 follows similar procedures as described in
Section 5.2.2.1 to set up ODU2 cross-connections on nodes S3, S5 and
S6 as well as the [STM-64 -> (ODU)] and [(ODU2) -> STM-64] adaptation
functions in nodes S3 and S6, as shown in Section 4.3.3. PNC1 also
configures the STM-64 links on the R1-S3 and R3-S6 multi-function
access links.
5.2.4. EVPL over ODU Service
In this scenario, described in Section 4.3.2, the access links are
configured as 10GE links, as described in Section 5.2.2 above.
The CNC requests, at the CMI, the MDSC to setup two EVPL services:
one between R1 and R2, and another between R1 and R8.
Following similar procedures as described in Section 5.2.2 and
Section 5.2.2.1, MDSC understands that:
* R1 and R2 are attached to the access links terminating
respectively on AN1-1 and AN1-8 LTPs in the MPI1 ETH Abstract
Topology, exposed by PNC1, and that R8 is attached to the access
link terminating on AN2-1 LTP in the MPI2 ETH Abstract Topology,
exposed by PNC2;
* To setup the first (single-domain) EVPL service, between R1 and
R2, it needs to coordinate the setup of a single-domain ODU0
Tunnel between the AN1-1 and AN1-8 TTPs, abstracting S3-1 and S6-1
TTPs, within the OTN Abstract Topology exposed by PNC1;
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* To setup the second (multi-domain) EPVL service, between R1 and
R8, it needs to coordinate the setup of a multi-domain ODU0 Tunnel
between the AN1-1 and AN2-1 TTPs, abstracting the ODU termination
and adaptation resources on S3-1 and S18-3 physical interfaces,
within the OTN Abstract Topologies exposed by PNC1 and PNC2,
respectively.
To setup the first (single-domain) EVPL service between R1 and R2,
the MDSC and PNC1 follows similar procedures as described in
Section 5.2.2.1 to set up ODU0 cross-connections on nodes S3, S5 and
S6 as well as the [VLAN -> (ODU0)] and [(ODU0) -> VLAN] adaptation
functions, in nodes S3 and S6, as shown in Section 4.3.2. PNC1 also
configures the 10GE link on the R1-S3 multi-function access link.
As part of the [VLAN -> (ODU0)] and [(ODU0) -> VLAN] adaptation
functions configurations in nodes S2 and S6, PNC1 configures also the
classification rules required to associate only the Ethernet client
traffic received with VLAN ID 10 on the R1-S3 and R2-S6 access links
with this EVPL service. The MDSC provides this information to PNC1
using the [CLIENT-SIGNAL] model.
To setup the second (multi-domain) EVPL service between R1 and R8,
the MDSC, PNC1, PNC2 and PNC3 follows similar procedures as described
in Section 5.2.2 to setup the ODU0 cross-connections within the
physical nodes S3, S1, S2, S31, S33, S15 and S18 as well as the [VLAN
-> (ODU0)] and [(ODU0) -> VLAN] adaptation functions in nodes S3 and
S18, as shown in Section 4.3.2. PNC2 also configures the 10GE link
on the R8-S18 multi-function access link (the R1-S3 10GE link has
been already configured when the first EVPL service has been setup).
As part of the [VLAN -> (ODU0)] and [(ODU0) -> VLAN] adaptation
functions configurations in nodes S3 and S18, PNC1 and, respectively,
PNC2 configure also the classification rules required to associated
only the Ethernet client traffic received with VLAN ID 20 on the
R1-S3 and R8-S18 access links with this EVPL service. The MDSC
provides this information to PNC1 and PNC2 using the [CLIENT-SIGNAL]
model.
5.3. YANG Models for Protection Configuration
5.3.1. Linear Protection (end-to-end)
As described in Section 4.5.1, the MDSC can decide to protect a
multi-domain connectivity service by setting up ODU linear protection
switching between edge nodes controlled by different PNCs (e.g.,
nodes S3 and S8, controlled by PNC1 and PNC2 respectively, to protect
services between R1 and R8).
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MDSC performs path computation, as described in Section 5.2, to
compute both the paths for working and protection transport entities:
the computed paths can pass through these exact PNC domains or
through different transit PNC domains.
Considering the case, described in Section 4.5.1, where the working
and protection transport entities pass through the same domain, MDSC
would perform the same steps described in Section 5.2 to setup the
ODU Tunnel and to configure the steering of the client traffic
between the access links and the ODU Tunnel. The only differences
are in the configuration of the ODU Tunnels.
MDSC requests at the MPI1, PNC1 to setup an ODU2 (Head Segment)
Tunnel within the MPI1 OTN Abstract Topology (Figure 3), using the TE
Tunnel YANG model, defined in [TE-TUNNEL], with the OTN technology-
specific augmentations, defined in [OTN-TUNNEL], with one primary
path and one secondary path with 1+1 protection switching enabled:
* Only the Source TTP (i.e., AN1-1 TTP) is specified (since it is a
Head Segment Tunnel), as described in Section 5.2.2;
* The egress point for the working transport entity in indicated in
the route-object-include-exclude list of the explicit-route-
objects of the primary path, as described in Section 5.2.2;
* The protection switching end-point in indicated in the route-
object-include-exclude list of the explicit-route-objects of the
secondary path:
- The first element references the TE-Node of the Source TTP
(i.e., AN1 TE-Node);
* The egress point for the protection transport entity in indicated
in the route-object-include-exclude list of the explicit-route-
objects of the secondary path:
- The last two element reference respectively the inter-domain
link terminating on AN1-6 LTP and the data plane resources
(i.e., the list of timeslots and the TPN) used by the ODU2
connection over that link.
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PNC1 knows, as described in the table in Section 5.1.1, that the
AN1-1 TTP, AN1-7 LTP and the AN1-6 LTP, within the MPI1 OTN Abstract
Topology it exposes at MPI1, correspond to S3-1 TTP, S2-3 LTP and the
S8-5 LTP, respectively, within its native topology. It also
understands, from the route-object-include-exclude list of the
explicit-route-objects of the secondary path configuration (whose
last two elements represent an inter-domain link), that node S3 is
the end-point of the protection group while the other end-point is
outside of its control domain.
PNC1 can perform path computation within its native topology and
setup the ODU connections in nodes S3, S1, S2, S4 and S8 as well as
configure the protection group in node S3.
5.3.2. Segmented Protection
Under specific policies, it is possible to deploy a segmented
protection for multi-domain services. The configuration of the
segmented protection can be divided into a few steps, considering the
example in Section 4.5.2, the following steps would be used.
MDSC performs path computation, as described in Section 5.2, to
compute all the paths for working and protection transport entities,
which pass through the same PNC domains and inter-domain links: the
MDSC would perform the same steps described in Section 5.2 to setup
the ODU Tunnel and to configure the steering of the client traffic
between the access links and the ODU Tunnel. The only differences
are in the configuration of the ODU Tunnels.
MDSC requests at the MPI1, PNC1 to setup an ODU2 (Head Segment)
Tunnel within the MPI1 OTN Abstract Topology (Figure 3), using the TE
Tunnel YANG model, defined in [TE-TUNNEL], with the OTN technology-
specific augmentations, defined in [OTN-TUNNEL], with one primary
path and one secondary path with 1+1 protection switching enabled:
* Only the Source TTP (i.e., AN1-1 TTP) is specified (since it is a
Head Segment Tunnel), as described in Section 5.2.2;
* The egress point (i.e., AN1-7 LTP) is indicated in the route-
object-include-exclude list of the explicit-route-objects of the
primary path, as described in Section 5.2.2;
* The protection switching end-points are indicated in the route-
object-include-exclude list of the explicit-route-objects of the
secondary path:
- The first element references the TE-Node of the Source TTP
(i.e., AN1 TE-Node);
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- The last element references the TE-Node of the egress point
(i.e., AN1 TE-Node).
As described in Section 5.2.2, PNC1 knows that the AN1-1 TTP and the
AN1-7 LTP, within the MPI1 OTN Abstract Topology it exposes at MPI1,
correspond to S3-1 TTP and the S2-3 LTP, respectively, within its
native topology. It also understands, from the route-object-include-
exclude list of the explicit-route-objects of the secondary path
configuration (whole last element represent an abstract node
terminating the inter-domain link used for the primary path), that
the protection group should be terminated in nodes S3 and S2.
PNC1 will perform path computations using its native topology and
setup the ODU connections in nodes S3, S1, S2, S4 and S8 as well as
configure the protection group in nodes S3 and S2.
Following similar requests from MDSC to setup ODU2 (Segment) Tunnels,
with segment protection, within the OTN Abstract Topologies they
expose. PNC3 then sets up ODU2 cross-connections on nodes S31, S32,
S33 and S34 and segment protection between nodes S31 and D34. PNC2
sets up ODU2 cross-connections on nodes S15, S12, S17 and S18 and
segment protection between nodes S15 and S18.
MDSC stitch the configuration above to form its internal view of the
end-to-end tunnel with segmented protection.
Given the configuration above, the protection capability has been
deployed on the tunnels. The head-end node of each domain can do the
switching once there is a failure on one of the tunnel segments. For
example, in Network domain 1, when there is a failure on the S1-S2
lin, the head-end nodes S2 and S3 will automatically do the switching
to S3-S4-S8-S2. This switching will be reported to the corresponding
PNC (PNC1 in this example) and then MDSC. Other PNCs (PNC2 and PNC3
in this example) will not be aware of the failure and switching, nor
do the nodes in network domains 2 and 3.
5.4. Notifications
Notification mechanisms are required for the scenarios analyzed in
this draft, as described in Section 4.6.
The notification mechanisms are protocol-dependent. It is assumed
that the RESTCONF protocol, defined in [RFC8040] is optional, and may
be used at the MPIs mentioned in this document.
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From the perspective of MPI, the MDSC is the client while the PNC is
acting as the server of the notification. The essential event
streams, subscription and processing rules after receiving
notification can be found in section 6 of [RFC8040].
Additional alarm reporting functions and alarm report management may
be found in [ITU-T_X.733] and [ITU-T_X.734]
Further detailed analysis of notification management is outside the
scope of this document.
5.5. Path Computation with Constraints
The path computation constraints that can be supported at the MPI
using the IETF YANG models defined in [TE-TUNNEL] and [PATH-COMPUTE].
When there is a technology-specific network (e.g., OTN), the
corresponding technology (e.g., OTN) model should also be used to
specify the tunnel information on MPI, with the constraint included
in TE Tunnel model.
Further detailed analysis is outside the scope of this document.
6. Security Considerations
This document analyses the applicability of the YANG models being
defined by the IETF to support OTN single and multi-domain scenarios.
When deploying ACTN functional components the securing of external
interfaces and hardening of resource datastores, the protection of
confidential information, and limit the access of function, should
all be carefully considered. Section 9 of [RFC8453] highlights that
implementations should consider encrypting data that flows between
key components, especially when they are implemented at remote nodes.
Further discussion on securing the interface between the MDSC and
PNCs via the MDSC-PNC Interface (MPI) is discussed in section 9.2 of
[RFC8453].
The YANG modules highlighted in this document are designed to be
accessed via network configuration protocols such as NETCONF
[RFC6241] or RESTCONF [RFC8040]. When using NETCONF, utilizing a
secure transport via Secure Shell (SSH) [RFC6242] is mandatory. If
using RESTCONF, then secure transport via TLS [RFC8446] is mandatory.
When using either NETCONF or RESTCONF, the use of Network
Configuration Access Control Model (NACM) [RFC8341] may be used to
restrict access to specific protocol operations and content.
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6.1. OTN Security
Inherently OTN networks ensure privacy and security via hard
partitioning of traffic onto dedicated circuits. The separation of
network traffic makes it difficult to intercept data transferred
between nodes over OTN-channelized links.
Within OTN environments, the (General Communication Channel) GCC is
used for OAM functions such as performance monitoring, fault
detection, and signaling. The GCC control channel should be secured
using a suitable mechanism.
7. IANA Considerations
This document requires no IANA actions.
8. References
8.1. Normative References
[CLIENT-SIGNAL]
Zheng, H., Guo, A., Busi, I., Snitser, A., and F. Lazzeri,
"A YANG Data Model for Transport Network Client Signals",
Work in Progress, Internet-Draft, draft-ietf-ccamp-client-
signal-yang-06, 5 January 2022,
<https://www.ietf.org/archive/id/draft-ietf-ccamp-client-
signal-yang-06.txt>.
[CLIENT-TOPO]
Zheng, H., Guo, A., Busi, I., Xu, Y., Zhao, Y., and X.
Liu, "A YANG Data Model for Ethernet TE Topology", Work in
Progress, Internet-Draft, draft-ietf-ccamp-eth-client-te-
topo-yang-02, 7 March 2022,
<https://www.ietf.org/archive/id/draft-ietf-ccamp-eth-
client-te-topo-yang-02.txt>.
[ITU-T_G.709]
ITU-T Recommendation G.709, "Interfaces for the optical
transport network", ITU-T G.709 , March 2020.
[ITU-T_G.808.1]
International Telecommunication Union, "Generic protection
switching - Linear trail and subnetwork protection", ITU-T
Recommendation G.808.1 , May 2014.
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[ITU-T_G.873.1]
International Telecommunication Union, "Optical transport
network (OTN): Linear protection", ITU-T Recommendation
G.873.1 , October 2017.
[OTN-TOPO] Zheng, H., Busi, I., Liu, X., Belotti, S., and O. G. D.
Dios, "A YANG Data Model for Optical Transport Network
Topology", Work in Progress, Internet-Draft, draft-ietf-
ccamp-otn-topo-yang-14, 7 March 2022,
<https://www.ietf.org/archive/id/draft-ietf-ccamp-otn-
topo-yang-14.txt>.
[OTN-TUNNEL]
Zheng, H., Busi, I., Belotti, S., Lopez, V., and Y. Xu,
"OTN Tunnel YANG Model", Work in Progress, Internet-Draft,
draft-ietf-ccamp-otn-tunnel-model-16, 8 April 2022,
<https://www.ietf.org/archive/id/draft-ietf-ccamp-otn-
tunnel-model-16.txt>.
[PATH-COMPUTE]
Busi, I., Belotti, S., Dios, O. G. D., Sharma, A., and D.
Ceccarelli, "A YANG Data Model for requesting path
computation", Work in Progress, Internet-Draft, draft-
ietf-teas-yang-path-computation-18, 22 March 2022,
<https://www.ietf.org/archive/id/draft-ietf-teas-yang-
path-computation-18.txt>.
[RFC4427] Mannie, E., Ed. and D. Papadimitriou, Ed., "Recovery
(Protection and Restoration) Terminology for Generalized
Multi-Protocol Label Switching (GMPLS)", RFC 4427,
DOI 10.17487/RFC4427, March 2006,
<https://www.rfc-editor.org/info/rfc4427>.
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>.
[RFC5521] Oki, E., Takeda, T., and A. Farrel, "Extensions to the
Path Computation Element Communication Protocol (PCEP) for
Route Exclusions", RFC 5521, DOI 10.17487/RFC5521, April
2009, <https://www.rfc-editor.org/info/rfc5521>.
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[RFC7926] Farrel, A., Ed., Drake, J., Bitar, N., Swallow, G.,
Ceccarelli, D., and X. Zhang, "Problem Statement and
Architecture for Information Exchange between
Interconnected Traffic-Engineered Networks", BCP 206,
RFC 7926, DOI 10.17487/RFC7926, July 2016,
<https://www.rfc-editor.org/info/rfc7926>.
[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>.
[RFC8453] Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for
Abstraction and Control of TE Networks (ACTN)", RFC 8453,
DOI 10.17487/RFC8453, August 2018,
<https://www.rfc-editor.org/info/rfc8453>.
[RFC8795] Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and
O. Gonzalez de Dios, "YANG Data Model for Traffic
Engineering (TE) Topologies", RFC 8795,
DOI 10.17487/RFC8795, August 2020,
<https://www.rfc-editor.org/info/rfc8795>.
[TE-TUNNEL]
Saad, T., Gandhi, R., Liu, X., Beeram, V. P., Bryskin, I.,
and O. G. D. Dios, "A YANG Data Model for Traffic
Engineering Tunnels, Label Switched Paths and Interfaces",
Work in Progress, Internet-Draft, draft-ietf-teas-yang-te-
29, 7 February 2022, <https://www.ietf.org/archive/id/
draft-ietf-teas-yang-te-29.txt>.
8.2. Informative References
[ACTN-YANG]
Lee, Y., Zheng, H., Ceccarelli, D., Yoon, B. Y., and S.
Belotti, "Applicability of YANG models for Abstraction and
Control of Traffic Engineered Networks", Work in Progress,
Internet-Draft, draft-ietf-teas-actn-yang-09, 7 March
2022, <https://www.ietf.org/archive/id/draft-ietf-teas-
actn-yang-09.txt>.
[ITU-T_X.733]
International Telecommunication Union, "Information
technology - Open Systems Interconnection - Systems
Management: Alarm reporting function", ITU-T
Recommendation X.733 , February 1992.
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[ITU-T_X.734]
International Telecommunication Union, "Information
technology - Open Systems Interconnection - Systems
Management: Event report management function", ITU-T
Recommendation X.734 , September 1992.
[MEF55] MEF Forum, "Lifecycle Service Orchestration (LSO):
Reference Architecture and Framework", MEF 55 , March
2016,
<https://www.mef.net/Assets/Technical_Specifications/PDF/
MEF_55.pdf>.
[ONF_TR-527]
Open Networking Foundation, "Functional Requirements for
Transport API", ONF Technical Recommendation TR-527 , May
2014.
[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>.
[RFC6898] Li, D., Ceccarelli, D., and L. Berger, "Link Management
Protocol Behavior Negotiation and Configuration
Modifications", RFC 6898, DOI 10.17487/RFC6898, March
2013, <https://www.rfc-editor.org/info/rfc6898>.
[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>.
[RFC8309] Wu, Q., Liu, W., and A. Farrel, "Service Models
Explained", RFC 8309, DOI 10.17487/RFC8309, January 2018,
<https://www.rfc-editor.org/info/rfc8309>.
[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>.
[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>.
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[RFC8792] Watsen, K., Auerswald, E., Farrel, A., and Q. Wu,
"Handling Long Lines in Content of Internet-Drafts and
RFCs", RFC 8792, DOI 10.17487/RFC8792, June 2020,
<https://www.rfc-editor.org/info/rfc8792>.
[TE-TUTORIAL]
Bryskin, I., Beeram, V. P., Saad, T., and X. Liu, "TE
Topology and Tunnel Modeling for Transport Networks", Work
in Progress, Internet-Draft, draft-ietf-teas-te-topo-and-
tunnel-modeling-06, 12 July 2020,
<https://www.ietf.org/archive/id/draft-ietf-teas-te-topo-
and-tunnel-modeling-06.txt>.
Appendix A. Validating a JSON fragment against a YANG Model
The objective is to have a tool that allows validating whether a
piece of JSON code embedded in an Internet-Draft is compliant with a
YANG model without using a client/server.
A.1. JSON CODE
This document provides some detailed JSON code examples to describe
how the YANG models being developed by the IETF (TEAS and CCAMP WG in
particular) may be used. The scenario examples are provided using
JSON to facilitate readability.
Different objects need to have an identifier. The convention used to
create mnemonic identifiers is to use the object name (e.g., S3 for
node S3), followed by its type (e.g., NODE), separated by a "-",
followed by "-ID". For example, the mnemonic identifier for AN1
would be AN1-NODE-ID.
The JSON language does not inherently support the insertion of
comments. This document will insert comments into the JSON code as
JSON name/value pair with the JSON name string starting with the "//"
characters. For example, when describing the example of a TE
Topology instance representing the ODU Abstract Topology exposed by
the Transport PNC, the following comment has been added to the JSON
code:
"// comment": "ODU Abstract Topology @ MPI",
The JSON code examples provided in this document have been validated
against the YANG models following the validation process described in
Appendix A, which would not consider the comments.
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To have successful validation of the examples, some numbering scheme
has been defined to assign identifiers to the different entities
which would pass the syntax checks. In that case, to simplify the
reading, another JSON name/value pair formatted as a comment and
using the mnemonic identifiers is also provided. For example, the
identifier of AN1 (AN1-NODE-ID) has been assumed to be "192.0.2.1"
and would be shown in the JSON code example using the two JSON name/
value pair:
"// te-node-id": "AN1-NODE-ID",
"te-node-id": "192.0.2.1",
The first JSON name/value pair will be automatically removed in the
first step of the validation process, while the second JSON name/
value pair will be validated against the YANG model definitions.
A.2. Manipulation of JSON fragments
This section describes the various ways JSON fragments are used in
the I-D processing and how to manage them.
Let's call "folded-JSON" the JSON embedded in the I-D: it fits the 72
chars width and it is acceptable for it to be invalid JSON.
We then define "unfolded-JSON" a valid JSON fragment having the same
contents of the "folded-JSON " without folding, i.e. limits on the
text width. The folding/unfolding operation may be done according to
[RFC8792]. The "unfolded-JSON" can be edited by the authors using
JSON editors with the advantages of syntax validation and pretty-
printing.
Both the "folded" and the "unfolded" JSON fragments can include
comments having descriptive fields and directives we'll describe
later to facilitate the reader and enable some automatic processing.
The presence of comments in the "unfolded-JSON" fragment makes it an
invalid JSON encoding of YANG data. Therefore we call "naked JSON"
the JSON where the comments have been stripped out: not only it is
valid JSON but it is a valid JSON encoding of YANG data.
The following schema resumes these definitions:
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unfold_it --> stripper -->
Folded-JSON Unfolded-JSON Naked JSON
<-- fold_it <-- author edits
<=72-chars? must may may
valid JSON? may must must
JSON-encoding
of YANG data? may may must
The validation toolchain has been designed to take a JSON in any of
the three formats and validate it automatically against a set of
relevant YANG modules using available open-source tools.
The tool used to validate the JSON examples in this document can be
found at: https://github.com/ietf-ccamp-wg/json-yang/tree/2.2
A.3. Comments in JSON fragments
We found it useful to introduce two kinds of comments, both defined
as key-value pairs where the key starts with "//":
* free-form descriptive comments, e.g."// comment" : "refine this"
to describe properties of JSON fragments.
* machine-usable directives e.g. "// header" : {"reference-drafts" :
{ "ietf-routing-types@2017-12-04": "rfc8294",}} which can be used
to automatically download from the network the relevant I-Ds or
RFCs and extract from them the YANG models of interest. This is
particularly useful to keep consistency when the drafting work is
rapidly evolving.
A.4. Validation of JSON fragments: DSDL-based approach
The idea is to generate a JSON driver file (JTOX) from YANG, then use
it to translate JSON to XML and validate it against the DSDL schemas,
as shown in Figure 8.
Useful link: https://github.com/mbj4668/pyang/wiki/XmlJson
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(2)
YANG-module ---> DSDL-schemas (RNG,SCH,DSRL)
| |
| (1) |
| |
Config/state JTOX-file | (4)
\ | |
\ | |
\ V V
JSON-file------------> XML-file ----------------> Output
(3)
Figure 8: DSDL-based approach for JSON code validation
In order to allow the use of comments following the convention
defined in Section 3, without impacting the validation process, these
comments will be automatically removed from the JSON-file that will
be validated.
A.5. Validation of JSON fragments: why not using an XSD-based approach
This approach has been analyzed and discarded because no longer
supported by pyang.
The idea is to convert YANG to XSD, JSON to XML and validate it
against the XSD, as shown in Figure 9:
(1)
YANG-module ---> XSD-schema - \ (3)
+--> Validation
JSON-file------> XML-file ----/
(2)
Figure 9: XSD-based approach for JSON code validation
The pyang support for the XSD output format was deprecated in 1.5 and
removed in 1.7.1. However, pyang 1.7.1 is necessary to work with
YANG 1.1 so the process shown in Figure 9 will stop just at step (1).
Appendix B. Detailed JSON Examples
The JSON code examples provided in this appendix have been validated
using the tools in Appendix A and folded using the tool in [RFC8792].
B.1. JSON Examples for Topology Abstractions
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B.1.1. JSON Code: mpi1-otn-topology.json
This is the JSON code reporting the OTN Topology @ MPI1:
=============== NOTE: '\\' line wrapping per RFC 8792 ===============
{
"// header": {
"last-update": "March 15, 2022",
"title": "ODU Black Topology @ MPI1",
"missing-attributes": true,
"reference-drafts": {
"ietf-routing-types@2017-12-04": "rfc8294",
"ietf-te-types@2020-06-10": "rfc8776",
"ietf-layer1-types@2021-02-19": "draft-ietf-ccamp-layer1-types\
\-10",
"ietf-network@2018-02-26": "rfc8345",
"ietf-network-topology@2018-02-26": "rfc8345",
"ietf-te-topology@2020-08-06": "rfc8795",
"ietf-otn-topology@2021-07-08": "draft-ietf-ccamp-otn-topo-yan\
\g-13"
}
},
"ietf-network:networks": {
"network": [
{
"network-id": "providerId/201/clientId/300/topologyId/otn-bl\
\ack-topology",
"network-types": {
"ietf-te-topology:te-topology": {
"ietf-otn-topology:otn-topology": {}
}
},
"ietf-te-topology:te-topology-identifier": {
"provider-id": 201,
"client-id": 300,
"topology-id": "otn-black-topology"
},
"// comment ietf-te-topology:te": "presence container requir\
\es: provider-id, client-id and te-topology-id",
"ietf-te-topology:te": {
"name": "OTN Black Topology @ MPI1"
},
"ietf-network:node": [
{
"// node description": {
"name": "AN1",
"identifier": "192.0.2.1",
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"type": "Abstract Node",
"physical node(s)": "The whole network domain 1"
},
"node-id": "192.0.2.1",
"ietf-te-topology:te-node-id": "192.0.2.1",
"ietf-te-topology:te": {
"te-node-attributes": {
"name": "AN11",
"is-abstract": [
null
],
"admin-status": "up"
},
"oper-status": "up",
"tunnel-termination-point": [
{
"// comment tunnel-tp-id": "AN1-1 TTP-ID (1 -> 0x0\
\1 -> 'AQ==' in base64)",
"tunnel-tp-id": "AQ==",
"name": "AN1-1 OTN TTP",
"// comment encoding and switching-capability": "O\
\TN (ODU)",
"switching-capability": "ietf-te-types:switching-o\
\tn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"// comment inter-layer-lock-id": "{ AN1-1 ILL-ID \
\(1) }",
"inter-layer-lock-id": [
1
],
"admin-status": "up",
"oper-status": "up"
},
{
"// comment tunnel-tp-id": "AN1-2 TTP-ID (2 -> 0x0\
\2 -> 'Ag==' in base64)",
"tunnel-tp-id": "Ag==",
"name": "AN1-2 OTN TTP",
"// comment encoding and switching-capability": "O\
\TN (ODU)",
"switching-capability": "ietf-te-types:switching-o\
\tn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"// comment inter-layer-lock-id": "{ AN1-2 ILL-ID \
\(2) }",
"inter-layer-lock-id": [
2
],
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"admin-status": "up",
"oper-status": "up"
},
{
"// comment tunnel-tp-id": "AN1-3 TTP-ID (3 -> 0x0\
\3 -> 'Awo=' in base64)",
"tunnel-tp-id": "Awo=",
"name": "AN1-3 OTN TTP",
"// comment encoding and switching-capability": "O\
\TN (ODU)",
"switching-capability": "ietf-te-types:switching-o\
\tn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"// comment inter-layer-lock-id": "{ AN1-3 ILL-ID \
\(3) }",
"inter-layer-lock-id": [
3
],
"admin-status": "up",
"oper-status": "up"
},
{
"// comment tunnel-tp-id": "AN1-8 TTP-ID (8 -> 0x0\
\8 -> 'CA==' in base64)",
"tunnel-tp-id": "CA==",
"name": "AN1-8 OTN TTP",
"// comment encoding and switching-capability": "O\
\TN (ODU)",
"switching-capability": "ietf-te-types:switching-o\
\tn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"// comment inter-layer-lock-id": "{ AN1-8 ILL-ID \
\(1) }",
"inter-layer-lock-id": [
8
],
"admin-status": "up",
"oper-status": "up"
}
]
},
"ietf-network-topology:termination-point": [
{
"// ltp description": {
"name": "AN1-1 LTP",
"link type(s)": "Multi-function (OTU2, STM-64 and \
\10GE)",
"physical node": "S3",
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"unnumberd/ifIndex": 1,
"port type": "tributary port",
"connected to": "R1"
},
"tp-id": "1",
"ietf-te-topology:te-tp-id": 1,
"ietf-te-topology:te": {
"name": "AN1-1 LTP",
"interface-switching-capability": [
{
"// comment encoding and switching-capability"\
\: "OTN (ODU)",
"switching-capability": "ietf-te-types:switchi\
\ng-otn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"max-lsp-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:otn": {
"odu-type": "ietf-layer1-types:ODU2"
}
}
}
]
}
],
"// not-present inter-domain-plug-id": "Use of plu\
\g-id for access Link is outside the scope of this document",
"// comment inter-layer-lock-id": "{ AN1-1 ILL-ID \
\(1) }",
"inter-layer-lock-id": [
1
],
"admin-status": "up",
"oper-status": "up",
"ietf-otn-topology:client-svc": {
"client-facing": true,
"supported-client-signal": [
"ietf-layer1-types:STM-64"
]
}
}
},
{
"// ltp description": {
"name": "AN1-2 LTP",
"link type(s)": "Multi-function (OTU2 and STM-64)"\
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\,
"physical node": "S6",
"unnumberd/ifIndex": 2,
"port type": "tributary port",
"connected to": "R3"
},
"tp-id": "2",
"ietf-te-topology:te-tp-id": 2,
"ietf-te-topology:te": {
"name": "AN1-2 LTP",
"interface-switching-capability": [
{
"// comment encoding and switching-capability"\
\: "OTN (ODU)",
"switching-capability": "ietf-te-types:switchi\
\ng-otn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"max-lsp-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:otn": {
"odu-type": "ietf-layer1-types:ODU2"
}
}
}
]
}
],
"// not-present inter-domain-plug-id": "Use of plu\
\g-id for access Link is outside the scope of this document",
"// comment inter-layer-lock-id": "{ AN1-2 ILL-ID \
\(2) }",
"inter-layer-lock-id": [
2
],
"admin-status": "up",
"oper-status": "up",
"ietf-otn-topology:client-svc": {
"client-facing": true,
"supported-client-signal": [
"ietf-layer1-types:STM-64"
]
}
}
},
{
"// ltp description": {
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"name": "AN1-3 LTP",
"link type(s)": "STM-64",
"physical node": "S6",
"unnumberd/ifIndex": 3,
"port type": "tributary port",
"connected to": "R4"
},
"tp-id": "3",
"ietf-te-topology:te-tp-id": 3,
"ietf-te-topology:te": {
"name": "AN1-3 LTP",
"// not-present interface-switching-capability": "\
\STM-64 Access Link only (no ODU switching)",
"// not-present inter-domain-plug-id": "Use of plu\
\g-id for access Link is outside the scope of this document",
"// comment inter-layer-lock-id": "{ AN1-3 ILL-ID \
\(3) }",
"inter-layer-lock-id": [
3
],
"admin-status": "up",
"oper-status": "up",
"ietf-otn-topology:client-svc": {
"client-facing": true,
"supported-client-signal": [
"ietf-layer1-types:STM-64"
]
}
}
},
{
"// ltp description": {
"name": "AN1-4 LTP",
"link type(s)": "OTU4",
"physical node": "S7",
"unnumberd/ifIndex": 3,
"port type": "inter-domain port",
"connected to": "S11"
},
"tp-id": "4",
"ietf-te-topology:te-tp-id": 4,
"ietf-te-topology:te": {
"name": "AN1-4 LTP",
"interface-switching-capability": [
{
"// comment encoding and switching-capability"\
\: "OTN (ODU)",
"switching-capability": "ietf-te-types:switchi\
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\ng-otn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"max-lsp-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:otn": {
"odu-type": "ietf-layer1-types:ODU4"
}
}
}
]
}
],
"// comment inter-domain-plug-id": "S7-S11 Plug-id\
\ (0x000711 -> AAcR)",
"inter-domain-plug-id": "AAcR",
"// not-present inter-layer-lock-id": "ODU Server \
\Layer topology not exposed",
"admin-status": "up",
"oper-status": "up",
"// not-present ietf-otn-topology:client-svc": "OT\
\N inter-domain link"
}
},
{
"// ltp description": {
"name": "AN1-5 LTP",
"link type(s)": "OTU4",
"physical node": "S8",
"unnumberd/ifIndex": 4,
"port type": "inter-domain port",
"connected to": "S12"
},
"tp-id": "5",
"ietf-te-topology:te-tp-id": 5,
"ietf-te-topology:te": {
"name": "AN1-5 LTP",
"interface-switching-capability": [
{
"// comment encoding and switching-capability"\
\: "OTN (ODU)",
"switching-capability": "ietf-te-types:switchi\
\ng-otn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"max-lsp-bandwidth": [
{
"priority": 0,
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"te-bandwidth": {
"ietf-otn-topology:otn": {
"odu-type": "ietf-layer1-types:ODU4"
}
}
}
]
}
],
"// comment inter-domain-plug-id": "S8-S12 Plug-id\
\ (0x000812 -> AAgS)",
"inter-domain-plug-id": "AAgS",
"// not-present inter-layer-lock-id": "ODU Server \
\Layer topology not exposed",
"admin-status": "up",
"oper-status": "up",
"// not-present ietf-otn-topology:client-svc": "OT\
\N inter-domain link"
}
},
{
"// ltp description": {
"name": "AN1-6 LTP",
"link type(s)": "OTU4",
"physical node": "S8",
"unnumberd/ifIndex": 5,
"port type": "inter-domain port",
"connected to": "S32"
},
"tp-id": "6",
"ietf-te-topology:te-tp-id": 6,
"ietf-te-topology:te": {
"name": "AN1-6 LTP",
"interface-switching-capability": [
{
"// comment encoding and switching-capability"\
\: "OTN (ODU)",
"switching-capability": "ietf-te-types:switchi\
\ng-otn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"max-lsp-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:otn": {
"odu-type": "ietf-layer1-types:ODU4"
}
}
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}
]
}
],
"// comment inter-domain-plug-id": "S8-S32 Plug-id\
\ (0x000832 -> AAgy)",
"inter-domain-plug-id": "AAgy",
"// not-present inter-layer-lock-id": "ODU Server \
\Layer topology not exposed",
"admin-status": "up",
"oper-status": "up",
"// not-present ietf-otn-topology:client-svc": "OT\
\N inter-domain link"
}
},
{
"// ltp description": {
"name": "AN1-7 LTP",
"link type(s)": "OTU4",
"physical node": "S2",
"unnumberd/ifIndex": 3,
"port type": "inter-domain port",
"connected to": "S31"
},
"tp-id": "7",
"ietf-te-topology:te-tp-id": 7,
"ietf-te-topology:te": {
"name": "AN1-7 LTP",
"interface-switching-capability": [
{
"// comment encoding and switching-capability"\
\: "OTN (ODU)",
"switching-capability": "ietf-te-types:switchi\
\ng-otn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"max-lsp-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:otn": {
"odu-type": "ietf-layer1-types:ODU4"
}
}
}
]
}
],
"// comment inter-domain-plug-id": "S2-S31 Plug-id\
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\ (0x000231 -> AAIx)",
"inter-domain-plug-id": "AAIx",
"// not-present inter-layer-lock-id": "ODU Server \
\Layer topology not exposed",
"admin-status": "up",
"oper-status": "up",
"// not-present ietf-otn-topology:client-svc": "OT\
\N inter-domain link"
}
}
]
}
],
"ietf-network-topology:link": [
{
"// link description": {
"name": "Access Link from AN1-1",
"type": "Multi-function access link (OTU2, STM-64 and \
\10GE)",
"physical link": "Link from S3-1 to R1"
},
"link-id": "teNodeId/192.0.2.1/teLinkId/1",
"source": {
"source-node": "192.0.2.1",
"source-tp": "1"
},
"// not-present destination": "access link",
"ietf-te-topology:te": {
"te-link-attributes": {
"name": "Access Link from AN1-1",
"// not-present external-domain": "The plug-id is us\
\ed instead of this container",
"// not-present is-abstract": "The access link is no\
\t abstract",
"interface-switching-capability": [
{
"// comment encoding and switching-capability": \
\"OTN (ODU)",
"switching-capability": "ietf-te-types:switching\
\-otn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"max-lsp-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:otn": {
"odu-type": "ietf-layer1-types:ODU4"
}
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}
}
]
}
],
"// comment label-restrictions": "Outside the scope \
\of this JSON example",
"max-link-bandwidth": {
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 1
}
]
}
},
"max-resv-link-bandwidth": {
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 1
}
]
}
},
"unreserved-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 1
}
]
}
}
],
"// not-present ietf-otn-topology:tsg": "Access Link\
\ with no HO-ODU termination and LO-ODU switching",
"admin-status": "up"
},
"oper-status": "up",
"// not-present is-transitional": "It is not a transit\
\ional link"
}
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},
{
"// link description": {
"name": "Access Link from AN1-2",
"type": "Multi-function access link (OTU2 and STM-64)"\
\,
"physical link": "Link from S6-2 to R3"
},
"link-id": "teNodeId/192.0.2.1/teLinkId/2",
"source": {
"source-node": "192.0.2.1",
"source-tp": "2"
},
"// not-present destination": "access link",
"ietf-te-topology:te": {
"te-link-attributes": {
"name": "Access Link from AN1-2",
"// not-present external-domain": "The plug-id is us\
\ed instead of this container",
"// not-present is-abstract": "The access link is no\
\t abstract",
"interface-switching-capability": [
{
"// comment encoding and switching-capability": \
\"OTN (ODU)",
"switching-capability": "ietf-te-types:switching\
\-otn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"max-lsp-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:otn": {
"odu-type": "ietf-layer1-types:ODU2"
}
}
}
]
}
],
"// comment label-restrictions": "Outside the scope \
\of this JSON example",
"max-link-bandwidth": {
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 1
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}
]
}
},
"max-resv-link-bandwidth": {
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 1
}
]
}
},
"unreserved-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 1
}
]
}
}
],
"// not-present ietf-otn-topology:tsg": "Access Link\
\ with no HO-ODU termination and LO-ODU switching",
"admin-status": "up"
},
"oper-status": "up",
"// not-present is-transitional": "It is not a transit\
\ional link"
}
},
{
"// link description": {
"name": "Access Link from AN1-3",
"type": "STM-64 Access link",
"physical link": "Link from S6-3 to R4"
},
"link-id": "teNodeId/192.0.2.1/teLinkId/3",
"source": {
"source-node": "192.0.2.1",
"source-tp": "3"
},
"// not-present destination": "access link",
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"ietf-te-topology:te": {
"te-link-attributes": {
"name": "Access Link from AN1-3",
"// not-present external-domain": "The plug-id is us\
\ed instead of this container",
"// not-present is-abstract": "The access link is no\
\t abstract",
"// not-present interface-switching-capability": "ST\
\M-64 Access Link only (no ODU switching)",
"// not-present max-link-bandwidth": "STM-64 Access \
\Link only (no ODU switching)",
"// not-present max-resv-link-bandwidth": "STM-64 Ac\
\cess Link only (no ODU switching)",
"// not-present unreserved-bandwidth": "STM-64 Acces\
\s Link only (no ODU switching)",
"// not-present ietf-otn-topology:tsg": "STM-64 Acce\
\ss Link only (no HO-ODU termination and LO-ODU switching)",
"admin-status": "up"
},
"oper-status": "up",
"// not-present is-transitional": "It is not a transit\
\ional link"
}
},
{
"// link description": {
"name": "Inter-domain Link from AN1-4",
"type": "OTU4 inter-domain link",
"physical link": "Link from S7-3 to S11"
},
"link-id": "teNodeId/192.0.2.1/teLinkId/4",
"source": {
"source-node": "192.0.2.1",
"source-tp": "4"
},
"// not-present destination": "inter-domain link",
"ietf-te-topology:te": {
"te-link-attributes": {
"name": "Inter-domain Link from AN1-4",
"// not-present external-domain": "The plug-id is us\
\ed instead of this container",
"// not-present is-abstract": "The access link is no\
\t abstract",
"interface-switching-capability": [
{
"// comment encoding and switching-capability": \
\"OTN (ODU)",
"switching-capability": "ietf-te-types:switching\
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\-otn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"max-lsp-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:otn": {
"odu-type": "ietf-layer1-types:ODU2"
}
}
}
]
}
],
"// comment label-restrictions": "Outside the scope \
\of this JSON example",
"max-link-bandwidth": {
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU4",
"number": 1
},
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 10
},
{
"odu-type": "ietf-layer1-types:ODU0",
"number": 80
}
]
}
},
"max-resv-link-bandwidth": {
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU4",
"number": 1
},
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 10
},
{
"odu-type": "ietf-layer1-types:ODU0",
"number": 80
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}
]
}
},
"unreserved-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU4",
"number": 1
},
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 10
},
{
"odu-type": "ietf-layer1-types:ODU0",
"number": 80
}
]
}
}
],
"ietf-otn-topology:tsg": "ietf-layer1-types:tsg-1.25\
\G",
"admin-status": "up"
},
"oper-status": "up",
"// not-present is-transitional": "It is not a transit\
\ional link"
}
},
{
"// link description": {
"name": "Inter-domain Link from AN1-5",
"type": "OTU4 inter-domain link",
"physical link": "Link from S8-4 to S12"
},
"link-id": "teNodeId/192.0.2.1/teLinkId/5",
"source": {
"source-node": "192.0.2.1",
"source-tp": "5"
},
"// not-present destination": "inter-domain link",
"ietf-te-topology:te": {
"te-link-attributes": {
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"name": "Inter-domain Link from AN1-5",
"// not-present external-domain": "The plug-id is us\
\ed instead of this container",
"// not-present is-abstract": "The access link is no\
\t abstract",
"interface-switching-capability": [
{
"// comment encoding and switching-capability": \
\"OTN (ODU)",
"switching-capability": "ietf-te-types:switching\
\-otn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"max-lsp-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:otn": {
"odu-type": "ietf-layer1-types:ODU4"
}
}
}
]
}
],
"// comment label-restrictions": "Outside the scope \
\of this JSON example",
"max-link-bandwidth": {
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU4",
"number": 1
},
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 10
},
{
"odu-type": "ietf-layer1-types:ODU0",
"number": 80
}
]
}
},
"max-resv-link-bandwidth": {
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
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"odu-type": "ietf-layer1-types:ODU4",
"number": 1
},
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 10
},
{
"odu-type": "ietf-layer1-types:ODU0",
"number": 80
}
]
}
},
"unreserved-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU4",
"number": 1
},
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 10
},
{
"odu-type": "ietf-layer1-types:ODU0",
"number": 80
}
]
}
}
],
"ietf-otn-topology:tsg": "ietf-layer1-types:tsg-1.25\
\G",
"admin-status": "up"
},
"oper-status": "up",
"// not-present is-transitional": "It is not a transit\
\ional link"
}
},
{
"// link description": {
"name": "Inter-domain Link from AN1-6",
"type": "OTU4 inter-domain link",
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"physical link": "Link from S8-5 to S32"
},
"link-id": "teNodeId/192.0.2.1/teLinkId/6",
"source": {
"source-node": "192.0.2.1",
"source-tp": "6"
},
"// not-present destination": "inter-domain link",
"ietf-te-topology:te": {
"te-link-attributes": {
"name": "Inter-domain Link from AN1-6",
"// not-present external-domain": "The plug-id is us\
\ed instead of this container",
"// not-present is-abstract": "The access link is no\
\t abstract",
"interface-switching-capability": [
{
"// comment encoding and switching-capability": \
\"OTN (ODU)",
"switching-capability": "ietf-te-types:switching\
\-otn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"max-lsp-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:otn": {
"odu-type": "ietf-layer1-types:ODU4"
}
}
}
]
}
],
"// comment label-restrictions": "Outside the scope \
\of this JSON example",
"max-link-bandwidth": {
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU4",
"number": 1
},
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 10
},
{
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"odu-type": "ietf-layer1-types:ODU0",
"number": 80
}
]
}
},
"max-resv-link-bandwidth": {
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU4",
"number": 1
},
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 10
},
{
"odu-type": "ietf-layer1-types:ODU0",
"number": 80
}
]
}
},
"unreserved-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU4",
"number": 1
},
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 10
},
{
"odu-type": "ietf-layer1-types:ODU0",
"number": 80
}
]
}
}
],
"ietf-otn-topology:tsg": "ietf-layer1-types:tsg-1.25\
\G",
"admin-status": "up"
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},
"oper-status": "up",
"// not-present is-transitional": "It is not a transit\
\ional link"
}
},
{
"// link description": {
"name": "Inter-domain Link from AN1-7",
"type": "OTU4 inter-domain link",
"physical link": "Link from S2-3 to S31"
},
"link-id": "teNodeId/192.0.2.1teLinkId/7",
"source": {
"source-node": "192.0.2.1",
"source-tp": "7"
},
"// not-present destination": "inter-domain link",
"ietf-te-topology:te": {
"te-link-attributes": {
"name": "Inter-domain Link from AN1-7",
"// not-present external-domain": "The plug-id is us\
\ed instead of this container",
"// not-present is-abstract": "The access link is no\
\t abstract",
"interface-switching-capability": [
{
"// comment encoding and switching-capability": \
\"OTN (ODU)",
"switching-capability": "ietf-te-types:switching\
\-otn",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"max-lsp-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:otn": {
"odu-type": "ietf-layer1-types:ODU4"
}
}
}
]
}
],
"// comment label-restrictions": "Outside the scope \
\of this JSON example",
"max-link-bandwidth": {
"te-bandwidth": {
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"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU4",
"number": 1
},
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 10
},
{
"odu-type": "ietf-layer1-types:ODU0",
"number": 80
}
]
}
},
"max-resv-link-bandwidth": {
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU4",
"number": 1
},
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 10
},
{
"odu-type": "ietf-layer1-types:ODU0",
"number": 80
}
]
}
},
"unreserved-bandwidth": [
{
"priority": 0,
"te-bandwidth": {
"ietf-otn-topology:odulist": [
{
"odu-type": "ietf-layer1-types:ODU4",
"number": 1
},
{
"odu-type": "ietf-layer1-types:ODU2",
"number": 10
},
{
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"odu-type": "ietf-layer1-types:ODU0",
"number": 80
}
]
}
}
],
"ietf-otn-topology:tsg": "ietf-layer1-types:tsg-1.25\
\G",
"admin-status": "up"
},
"oper-status": "up",
"// not-present is-transitional": "It is not a transit\
\ional link"
}
}
]
}
]
}
}
B.1.2. JSON Code: mpi1-eth-topology.json
This is the JSON code reporting the ETH Topology @ MPI1:
=============== NOTE: '\\' line wrapping per RFC 8792 ===============
{
"// header": {
"last-update": "March 15, 2022",
"title": "ETH Black Topology @ MPI1",
"reference-drafts": {
"ietf-routing-types@2017-12-04": "rfc8294",
"ietf-te-types@2020-06-10": "rfc8776",
"ietf-network@2018-02-26": "rfc8345",
"ietf-network-topology@2018-02-26": "rfc8345",
"ietf-te-topology@2020-08-06": "rfc8795",
"ietf-eth-tran-types@2021-07-07": "draft-ietf-ccamp-client-sig\
\nal-yang-05",
"ietf-eth-te-topology@2019-11-18": "draft-ietf-ccamp-eth-clien\
\t-te-topo-yang-00"
}
},
"ietf-network:networks": {
"network": [
{
"network-id": "providerId/201/clientId/300/topologyId/eth-bl\
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\ack-topology",
"network-types": {
"ietf-te-topology:te-topology": {
"ietf-eth-te-topology:eth-tran-topology": {}
}
},
"ietf-te-topology:te-topology-identifier": {
"provider-id": 201,
"client-id": 300,
"topology-id": "eth-black-topology"
},
"// comment ietf-te-topology:te": "presence container requir\
\es: provider-id, client-id and te-topology-id",
"ietf-te-topology:te": {
"name": "ETH Black Topology @ MPI1"
},
"ietf-network:node": [
{
"// node description": {
"name": "AN1",
"identifier": "192.0.2.1",
"type": "Abstract Node",
"physical node(s)": "The whole network domain 1"
},
"node-id": "192.0.2.1",
"ietf-te-topology:te-node-id": "192.0.2.1",
"// comment supporting-node": "Not used because topology\
\ hierarchy is outside the scope of this JSON example",
"ietf-te-topology:te": {
"te-node-attributes": {
"name": "AN11",
"is-abstract": [
null
],
"admin-status": "up"
},
"oper-status": "up",
"// not-present tunnel-termination-point": "ETH Access\
\ Links only (no ETH TE switching)"
},
"ietf-network-topology:termination-point": [
{
"// ltp description": {
"name": "AN1-1 LTP",
"link type(s)": "Multi-function (OTU2, STM-64 and \
\10GE)",
"physical node": "S3",
"unnumberd/ifIndex": 1,
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"port type": "tributary port",
"connected to": "R1"
},
"tp-id": "1",
"ietf-te-topology:te-tp-id": 1,
"ietf-te-topology:te": {
"name": "AN1-1 LTP",
"// not-present interface-switching-capability": "\
\ETH Access Link only (no ETH TE switching)",
"// comment inter-domain-plug-id": "Use of plug-id\
\ for access Link is outside the scope of this document",
"// comment inter-layer-lock-id": "AN1-1 ILL-ID (1\
\)",
"inter-layer-lock-id": [
1
],
"admin-status": "up",
"oper-status": "up"
},
"// comment ietf-eth-te-topology:ingress-bandwidth-p\
\rofile": "Outside the scope of this JSON example",
"ietf-eth-te-topology:eth-svc": {
"client-facing": true,
"supported-classification": {
"port-classification": true,
"vlan-classification": {
"vlan-tag-classification": true,
"outer-tag": {
"supported-tag-types": [
"ietf-eth-tran-types:classify-c-vlan"
],
"vlan-range": "1-4094"
}
}
},
"supported-vlan-operations": {
"transparent-vlan-operations": true
}
}
},
{
"// ltp description": {
"name": "AN1-8 LTP",
"link type(s)": "10GE",
"physical node": "S6",
"unnumberd/ifIndex": 1,
"port type": "tributary port",
"connected to": "R2"
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},
"tp-id": "8",
"ietf-te-topology:te-tp-id": 8,
"ietf-te-topology:te": {
"name": "AN1-8 LTP",
"// comment inter-layer-lock-id": "AN1-8 ILL-ID (8\
\)",
"// not-present interface-switching-capability": "\
\ETH Access Link only (no ETH TE switching)",
"// comment inter-domain-plug-id": "Use of plug-id\
\ for access Link is outside the scope of this document",
"inter-layer-lock-id": [
8
],
"admin-status": "up",
"oper-status": "up"
},
"// comment ingress-bandwidth-profile": "Outside the\
\ scope of this JSON example",
"ietf-eth-te-topology:eth-svc": {
"client-facing": true,
"supported-classification": {
"port-classification": true,
"vlan-classification": {
"vlan-tag-classification": true,
"outer-tag": {
"supported-tag-types": [
"ietf-eth-tran-types:classify-c-vlan"
],
"vlan-range": "1-4094"
}
}
},
"supported-vlan-operations": {
"transparent-vlan-operations": true
}
}
}
]
}
],
"ietf-network-topology:link": [
{
"// link description": {
"name": "Access Link from AN1-1",
"type": "Multi-function access link (OTU2, STM-64 and \
\10GE)",
"physical link": "Link from S3-1 to R1"
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},
"link-id": "teNodeId/192.0.2.1/teLinkId/1",
"source": {
"source-node": "192.0.2.1",
"source-tp": "1"
},
"// not-present destination": "access link",
"ietf-te-topology:te": {
"te-link-attributes": {
"name": "Access Link from AN1-1",
"// not-present external-domain": "The plug-id is us\
\ed instead of this container",
"// not-present is-abstract": "The access link is no\
\t abstract",
"// not-present interface-switching-capability": "ET\
\H Access Link only (no ETH TE switching)",
"// not-present label-restrictions": "ETH Access Lin\
\k only (no ETH TE switching)",
"// not-present max-link-bandwidth": "ETH Access Lin\
\k only (no ETH TE switching)",
"// not-present max-resv-link-bandwidth": "ETH Acces\
\s Link only (no ETH TE switching)",
"// not-present unreserved-bandwidth": "ETH Access L\
\ink only (no ETH TE switching)",
"admin-status": "up"
},
"oper-status": "up",
"// not-present is-transitional": "It is not a transit\
\ional link"
}
},
{
"// link description": {
"name": "Access Link from AN1-8",
"type": "10GE access link",
"physical link": "Link from S6-1 to R2"
},
"link-id": "teNodeId/192.0.2.1/teLinkId/8",
"source": {
"source-node": "192.0.2.1",
"source-tp": "8"
},
"// not-present destination": "access link",
"ietf-te-topology:te": {
"te-link-attributes": {
"name": "Access Link from AN1-8",
"// not-present external-domain": "The plug-id is us\
\ed instead of this container",
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"// not-present is-abstract": "The access link is no\
\t abstract",
"// not-present interface-switching-capability": "ET\
\H Access Link only (no ETH TE switching)",
"// not-present label-restrictions": "ETH Access Lin\
\k only (no ETH TE switching)",
"// not-present max-link-bandwidth": "ETH Access Lin\
\k only (no ETH TE switching)",
"// not-present max-resv-link-bandwidth": "ETH Acces\
\s Link only (no ETH TE switching)",
"// not-present unreserved-bandwidth": "ETH Access L\
\ink only (no ETH TE switching)",
"admin-status": "up"
},
"oper-status": "up",
"// not-present is-transitional": "It is not a transit\
\ional link"
}
}
]
}
]
}
}
B.2. JSON Examples for Service Configuration
B.2.1. JSON Code: mpi1-odu2-service-config.json
This is the JSON code reporting the ODU2 transit service
configuration @ MPI1:
=============== NOTE: '\\' line wrapping per RFC 8792 ===============
{
"// header": {
"// last-update": "March 15, 2022",
"// title": "ODU2 Service Configuration @ MPI1",
"reference-drafts": {
"ietf-routing-types@2017-12-04": "rfc8294",
"ietf-te-types@2020-06-10": "rfc8776",
"ietf-layer1-types@2021-02-19": "draft-ietf-ccamp-layer1-types-1\
\0",
"ietf-te@2021-02-20": "draft-ietf-teas-yang-te-26",
"ietf-otn-tunnel@2021-06-25": "draft-ietf-ccamp-otn-tunnel-model\
\-14"
}
},
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"// missing-attributes": true,
"// restconf_operation": {
"operation": "POST",
"url": "http://{{PNC1-ADDR}}/restconf/data/ietf-te:te/tunnels"
},
"ietf-te:te": {
"tunnels": {
"tunnel": [
{
"name": "mpi1-odu2-service",
"// comment identifier": "ODU2-SERVICE-TUNNEL-ID @ MPI1",
"identifier": 1,
"description": "ODU2 Service implemented by ODU2 OTN Tunne\
\l Segment @ MPI1",
"// comment encoding and switching-type": "OTN (ODU)",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"switching-type": "ietf-te-types:switching-otn",
"// not-present source": "Transit tunnel segment",
"// not-present src-tunnel-tp-id": "Transit tunnel segment\
\",
"// not-present destination": "Transit tunnel segment",
"// not-present dst-tunnel-tp-id": "Transit tunnel segment\
\",
"bidirectional": true,
"// default protection": {
"// default enable": false
},
"// default restoration": {
"// default enable": false
},
"// comment te-topology-identifier": "ODU Black Topology @\
\ MPI1",
"te-topology-identifier": {
"provider-id": 201,
"client-id": 300,
"topology-id": "otn-black-topology"
},
"te-bandwidth": {
"ietf-otn-tunnel:otn": {
"ietf-otn-tunnel:odu-type": "ietf-layer1-types:ODU2"
}
},
"admin-state": "ietf-te-types:tunnel-admin-state-up",
"primary-paths": {
"primary-path": [
{
"name": "mpi1-odu2-service-primary-path",
"// not-present te-bandwidth": "The tunnel bandwidth\
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\ is used",
"explicit-route-objects-always": {
"route-object-include-exclude": [
{
"// comment": "Tunnel hand-off OTU2 ingress in\
\terface (S3-1 -> AN1-1)",
"index": 1,
"explicit-route-usage": "ietf-te-types:route-i\
\nclude-object",
"unnumbered-link-hop": {
"// comment node-id": "AN1 NODE-ID",
"node-id": "192.0.2.1",
"// comment link-tp-id": "AN1-1 LTP",
"link-tp-id": 1,
"// default hop-type": "strict",
"// default direction": "outgoing"
}
},
{
"// comment": "Tunnel hand-off ODU2 ingress la\
\bel (ODU2 over OTU2) at S3-1 (AN1-1)",
"index": 2,
"explicit-route-usage": "ietf-te-types:route-i\
\nclude-object",
"label-hop": {
"te-label": {
"ietf-otn-tunnel:otn-tpn": 1,
"// not-present ietf-otn-tunnel:tsg": "Not\
\ applicable for ODUk over OTUk",
"// not-present ietf-otn-tunnel:ts-list": \
\"Not applicable for ODUk over OTUk",
"// default direction": "forward"
}
}
},
{
"// comment": "Tunnel hand-off OTU4 egress int\
\erface (S2-3 -> AN1-7)",
"index": 3,
"explicit-route-usage": "ietf-te-types:route-i\
\nclude-object",
"unnumbered-link-hop": {
"// comment node-id": "AN1 Node",
"node-id": "192.0.2.1",
"// comment link-tp-id": "AN1-7 LTP",
"link-tp-id": 7,
"// default hop-type": "strict",
"// default direction": "outgoing"
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}
},
{
"// comment": "Tunnel hand-off ODU2 egress lab\
\el (ODU2 over OTU4) at S2-3 (AN1-7)",
"index": 4,
"explicit-route-usage": "ietf-te-types:route-i\
\nclude-object",
"label-hop": {
"te-label": {
"ietf-otn-tunnel:otn-tpn": 1,
"ietf-otn-tunnel:tsg": "ietf-layer1-types:\
\tsg-1.25G",
"ietf-otn-tunnel:ts-list": "1-8",
"// default direction": "forward"
}
}
}
]
}
}
]
}
}
]
}
}
}
B.2.2. JSON Code: mpi1-odu2-tunnel-config.json
This is the JSON code reporting the ODU2 head tunnel segment
configuration @ MPI1:
=============== NOTE: '\\' line wrapping per RFC 8792 ===============
{
"// header": {
"last-update": "March 15, 2022",
"title": "ODU2 Tunnel Configuration @ MPI1",
"reference-drafts": {
"ietf-routing-types@2017-12-04": "rfc8294",
"ietf-te-types@2020-06-10": "rfc8776",
"ietf-layer1-types@2021-02-19": "draft-ietf-ccamp-layer1-types\
\-10",
"ietf-te@2021-02-20": "draft-ietf-teas-yang-te-26",
"ietf-otn-tunnel@2021-06-25": "draft-ietf-ccamp-otn-tunnel-mod\
\el-14"
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},
"// missing-attributes": true,
"// restconf-operation": {
"operation": "POST",
"url": "http://{{PNC1-ADDR}}/restconf/data/ietf-te:te/tunnels"
}
},
"ietf-te:te": {
"tunnels": {
"tunnel": [
{
"name": "mpi1-odu2-tunnel",
"// comment identifier": "ODU2-TUNNEL-ID @ MPI1",
"identifier": 2,
"description": "TNBI Example for an ODU2 Head Tunnel Segme\
\nt @ MPI1",
"// comment encoding and switching-type": "OTN (ODU)",
"encoding": "ietf-te-types:lsp-encoding-oduk",
"switching-type": "ietf-te-types:switching-otn",
"// comment source": "AN1 Node-ID",
"source": "192.0.2.1",
"// comment src-tunnel-tp-id": "AN1-1 TTP-ID (1 -> 0x01 ->\
\ 'AQ==' in base64)",
"src-tunnel-tp-id": "AQ==",
"// not-present destination": "Head tunnel segment",
"// not-present dst-tunnel-tp-id": "Head tunnel segment",
"bidirectional": true,
"// default protection": {
"// default enable": false
},
"// default restoration": {
"// default enable": false
},
"// comment te-topology-identifier": "ODU Black Topology @\
\ MPI1",
"te-topology-identifier": {
"provider-id": 201,
"client-id": 300,
"topology-id": "otn-black-topology"
},
"te-bandwidth": {
"ietf-otn-tunnel:otn": {
"ietf-otn-tunnel:odu-type": "ietf-layer1-types:ODU2"
}
},
"admin-state": "ietf-te:tunnel-admin-auto",
"primary-paths": {
"primary-path": [
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{
"name": "mpi1-odu2-tunnel-primary-path",
"// not-present te-bandwidth": "The tunnel bandwidth\
\ is used",
"explicit-route-objects-always": {
"route-object-include-exclude": [
{
"// comment": "Tunnel hand-off OTU4 egress int\
\erface (AN1-7 LTP)",
"index": 1,
"explicit-route-usage": "ietf-te-types:route-i\
\nclude-object",
"unnumbered-link-hop": {
"// comment node-id": "AN1 NODE-ID",
"node-id": "192.0.2.1",
"// comment link-tp-id": "AN1-7 LTP-ID",
"link-tp-id": 7,
"// default hop-type": "strict",
"// default direction": "outgoing"
}
},
{
"// comment": "Tunnel hand-off ODU2 egress lab\
\el (ODU2 over OTU4)",
"index": 2,
"explicit-route-usage": "ietf-te-types:route-i\
\nclude-object",
"label-hop": {
"te-label": {
"ietf-otn-tunnel:otn-tpn": 2,
"ietf-otn-tunnel:tsg": "ietf-layer1-types:\
\tsg-1.25G",
"ietf-otn-tunnel:ts-list": "9-16",
"// default direction": "forward"
}
}
}
]
}
}
]
}
}
]
}
}
}
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B.2.3. JSON Code: mpi1-epl-service-config.json
This is the JSON code reporting the EPL service configuration @ MPI:
=============== NOTE: '\\' line wrapping per RFC 8792 ===============
{
"// header": {
"last-update": "March 15, 2022",
"title": "EPL Configuration @ MPI1",
"reference-drafts": {
"ietf-routing-types@2017-12-04": "rfc8294",
"ietf-te@2021-05-16": "draft-ietf-teas-yang-te-27",
"ietf-te-types@2020-06-10": "rfc8776",
"ietf-eth-tran-types@2021-07-07": "draft-ietf-ccamp-client-sig\
\nal-yang-05",
"ietf-eth-tran-service@2021-01-11": "draft-ietf-ccamp-client-s\
\ignal-yang-05"
},
"missing-attributes": true,
"restconf-operation": {
"operation": "POST",
"url": "http://{{PNC1-ADDR}}/restconf/data/ietf-eth-tran-servi\
\ce:etht-svc/etht-svc-instances"
}
},
"ietf-eth-tran-service:etht-svc": {
"etht-svc-instances": [
{
"etht-svc-name": "mpi1-epl-service",
"etht-svc-descr": "TNBI Example for an EPL over ODU2 Service\
\ @ MPI1",
"// default etht-svc-type": "ietf-eth-tran-types:p2p-svc",
"// comment te-topology-identifier": "ETH Black Topology @ M\
\PI1",
"te-topology-identifier": {
"provider-id": 201,
"client-id": 300,
"topology-id": "eth-black-topology"
},
"etht-svc-end-points": [
{
"// comment": "10GE Service End-Point at the access inte\
\rface (S3-1 -> AN1-1)",
"etht-svc-end-point-name": "mpi1-epl-an1-1-service-end-p\
\oint",
"etht-svc-end-point-descr": "Ethernet Service End-Point \
\at S3-1 (AN1-1) access link",
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"etht-svc-access-points": [
{
"// comment": "10GE Service Access Point at the acce\
\ss interface (S3-1 -> AN1-1)",
"access-point-id": "mpi-epl-an1-1-service-access-poi\
\nt",
"// comment access-node-id": "AN1 NODE-ID",
"access-node-id": "192.0.2.1",
"// comment access-ltp-id": "AN1-1 LTP-ID",
"access-ltp-id": 1
}
],
"service-classification-type": "ietf-eth-tran-types:port\
\-classification",
"// comment ingress-egress-bandwidth-profile": "Outside \
\the scope of this JSON example",
"// comment not present vlan-operations": "Transparent V\
\LAN operations"
}
],
"underlay": {
"otn-tunnels": [
{
"// comment tunnel-name": "ODU2 Head Tunnel Segment @ \
\MPI1",
"name": "mpi1-odu2-tunnel"
}
]
},
"admin-status": "ietf-te-types:tunnel-admin-state-up"
}
]
}
}
Acknowledgments
The authors would like to thank all members of the Transport NBI
Design Team involved in the definition of use cases, gap analysis and
guidelines for using the IETF YANG models at the Northbound Interface
(NBI) of a Transport SDN Controller.
The authors would like to thank Xian Zhang, Anurag Sharma, Sergio
Belotti, Tara Cummings, Michael Scharf, Karthik Sethuraman, Oscar
Gonzalez de Dios, and Hans Bjursrom for having initiated the work on
gap analysis for transport NBI and having provided foundations work
for the development of this document.
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The authors would like to thank the authors of the TE Topology and
Tunnel YANG models [RFC8795] and [TE-TUNNEL], in particular, Igor
Bryskin, Vishnu Pavan Beeram, Tarek Saad and Xufeng Liu, for their
support in addressing any gap identified during the analysis work.
The authors would like to thank Henry Yu and Aihua Guo for their
input and review of the URIs structures used within the JSON code
examples.
This work was supported in part by the European Commission funded
H2020-ICT-2016-2 METRO-HAUL project (G.A. 761727).
This document was prepared using kramdown.
Previous versions of this document was prepared using 2-Word-
v2.0.template.dot.
Contributors
Yang Zhao
China Mobile
Email: zhaoyangyjy@chinamobile.com
Sergio Belotti
Nokia
Email: sergio.belotti@nokia.com
Gianmarco Bruno
Ericsson
Email: gianmarco.bruno@ericsson.com
Young Lee
Sung Kyun Kwan University
Email: younglee.tx@gmail.com
Victor Lopez
Nokia
Email: victor.lopez@nokia.com
Carlo Perocchio
Ericsson
Email: carlo.perocchio@ericsson.com
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Ricard Vilalta
CTTC
Email: ricard.vilalta@cttc.es
Michael Scharf
Hochschule Esslingen - University of Applied Sciences
Email: michael.scharf@hs-esslingen.de
Dieter Beller
Nokia
Email: dieter.beller@nokia.com
Authors' Addresses
Italo Busi (editor)
Huawei
Email: italo.busi@huawei.com
Daniel King (editor)
Old Dog Consulting
Email: daniel@olddog.co.uk
Haomian Zheng (editor)
Huawei
Email: zhenghaomian@huawei.com
Yunbin Xu (editor)
CAICT
Email: xuyunbin@ritt.cn
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