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Versions: (draft-ietf-ccamp-transport-nbi-use-cases) 00 01 02 03 04

CCAMP Working Group                                             I. Busi
Internet Draft                                                   Huawei
Intended status: Informational                                  D. King
                                                   Lancaster University
                                                               H. Zheng
                                                                 Huawei
                                                                  Y. Xu
                                                                  CAICT

Expires: May 2019                                      November 4, 2018





          Transport Northbound Interface Applicability Statement
              draft-ietf-ccamp-transport-nbi-app-statement-04


Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on May 4, 2019.








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Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors. All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document. Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document. Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Abstract

   Transport network domains, including Optical Transport Network (OTN)
   and Wavelength Division Multiplexing (WDM) networks, are typically
   deployed based on a single vendor or technology platforms. They are
   often managed using proprietary interfaces to dedicated Element
   Management Systems (EMS), Network Management Systems (NMS) and
   increasingly Software Defined Network (SDN) controllers.

   A well-defined open interface to each domain management system or
   controller is required for network operators to facilitate control
   automation and orchestrate end-to-end services across multi-domain
   networks. These functions may be enabled using standardized data
   models (e.g. YANG), and appropriate protocol (e.g., RESTCONF).

   This document analyses the applicability of the YANG models being
   defined by IETF (TEAS and CCAMP WGs in particular) to support OTN
   single and multi-domain scenarios.

Table of Contents

   1. Introduction...................................................4
      1.1. The scope of this document................................4
      1.2. Assumptions...............................................5
   2. Terminology....................................................6
   3. Conventions used in this document..............................7
      3.1. Topology and traffic flow processing......................7
      3.2. JSON code.................................................8
   4. Scenarios Description..........................................9



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      4.1. Reference Network.........................................9
         4.1.1. Single-Domain Scenario..............................12
      4.2. Topology Abstractions....................................12
      4.3. Service Configuration....................................14
         4.3.1. ODU Transit.........................................15
         4.3.2. EPL over ODU........................................16
         4.3.3. Other OTN Clients Services..........................17
         4.3.4. EVPL over ODU.......................................18
         4.3.5. EVPLAN and EVPTree Services.........................19
         4.3.6. Dynamic Service Configuration.......................20
      4.4. Multi-function Access Links..............................21
      4.5. Protection and Restoration Configuration.................22
         4.5.1. Linear Protection (end-to-end)......................22
         4.5.2. Segmented Protection................................23
         4.5.3. End-to-End Dynamic restoration......................24
         4.5.4. Segmented Dynamic Restoration.......................25
      4.6. Service Modification and Deletion........................25
      4.7. Notification.............................................25
      4.8. Path Computation with Constraint.........................26
   5. YANG Model Analysis...........................................27
      5.1. YANG Models for Topology Abstraction.....................27
         5.1.1. Domain 1 Black Topology Abstraction.................28
         5.1.2. Domain 2 Black Topology Abstraction.................30
         5.1.3. Domain 3 White Topology Abstraction.................30
         5.1.4. Multi-domain Topology Stitching.....................31
         5.1.5. Access Links........................................33
      5.2. YANG Models for Service Configuration....................35
         5.2.1. ODU Transit Service.................................37
            5.2.1.1. Single Domain Example..........................39
         5.2.2. EPL over ODU Service................................40
         5.2.3. Other OTN Client Services...........................42
         5.2.4. EVPL over ODU Service...............................42
      5.3. YANG Models for Protection Configuration.................43
         5.3.1. Linear Protection (end-to-end)......................43
         5.3.2. Segmented Protection................................43
   6. Security Considerations.......................................43
   7. IANA Considerations...........................................44
   8. References....................................................44
      8.1. Normative References.....................................44
      8.2. Informative References...................................45
   9. Acknowledgments...............................................46
   Appendix A.    Validating a JSON fragment against a YANG Model...47
      A.1.  Manipulation of JSON fragments..........................47
      A.2.  Comments in JSON fragments..............................48



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      A.3.  Validation of JSON fragments: DSDL-based approach.......48
      A.4.  Validation of JSON fragments: why not using a XSD-based
      approach......................................................49
   Appendix B.    Detailed JSON Examples............................50
      B.1.  JSON Examples for Topology Abstractions.................50
         B.1.1.   JSON Code: mpi1-otn-topology.json.................50
      B.2.  JSON Examples for Service Configuration.................66
         B.2.1.   JSON Code: mpi1-odu2-service-config.json..........66
         B.2.2.   JSON Code: mpi1-odu2-tunnel-config.json...........70
         B.2.3.   JSON Code: mpi1-epl-service-config.json...........70

1. Introduction

   Transport of packet services are 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. These services are typically
   setup using stovepipe NMS and EMS platforms, often requiring
   propriety management platforms and legacy management interfaces. A
   clear goal of operators will be to automate the setup of transport
   services across multiple transport technology domains.

   A common open interface (API) to each domain controller and or
   management system is pre-requisite for network operators to control
   multi-vendor and multi-domain networks and also enable service
   provisioning coordination/automation. This can be achieved by using
   standardized YANG models, used together with an appropriate protocol
   (e.g., [RFC8040]).

   This document analyses the applicability of the YANG models being
   defined by IETF (TEAS and CCAMP WGs in particular) to support OTN
   single and multi-domain scenarios.

1.1. The scope of this document

   This document assumes a reference architecture, including interfaces,
   based on the Abstraction and Control of Traffic-Engineered Networks
   (ACTN), defined in [RFC8453].

   The focus of this document is on the MPI (interface between the Multi
   Domain Service Coordinator (MDSC) and a Physical Network Controller
   (PNC), controlling a transport network domain).





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   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].

   Detailed analysis of the CMI (interface between the Customer Network
   Controller (CNC) and the MDSC) as well as of the interface between
   service and network orchestrators are outside the scope of this
   document. However, some considerations and assumptions about the
   information could be described when needed.

   The relationship between the current IETF YANG models and the type of
   ACTN interfaces can be found in [ACTN-YANG]. Therefore, it considers
   the TE Topology YANG model defined in [TE-TOPO], with the OTN
   Topology augmentation defined in [OTN-TOPO] and the TE Tunnel YANG
   model defined in [TE-TUNNEL], with the OTN Tunnel augmentation
   defined in [OTN-TUNNEL].

   The ONF Technical Recommendations for Functional Requirements for the
   transport API in [ONF TR-527] and the ONF transport API multi-domain
   examples in [ONF GitHub] have been considered as input for defining
   the reference scenarios analyzed in this document.

1.2. Assumptions

   This document is making the following assumptions, still to be
   validated with TEAS WG:

   1. The MDSC can request, at the MPI, a PNC to setup a Transit Tunnel
      Segment using the TE Tunnel YANG model: in this case, since the
      endpoints of the E2E Tunnel are outside the domain controlled by
      that PNC, the MDSC would not specify any source or destination TTP
      (i.e., it would leave the source, destination, src-tp-id and dst-
      tp-id attributes empty) for the tunnel and it would use the
      explicit-route-object/route-object-include-exclude list to specify
      the ingress and egress links for each path of the Transit Tunnel
      Segment.

   2. 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
      [TE-TOPO] is being updated to report the label set information.

   This document is also making the following assumptions, still to be
   validated with CCAMP WG:



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   1. The topology information for the Ethernet access links is modelled
      using the YANG model defined in [CLIENT-TOPO].

   2. The service information for Ethernet and other OTN client layer
      services are modelled using the YANG model defined in [Client-
      Signal].

   Finally, the Network Elements (NEs) described in the scenarios used
   in document are using ODU switching. It is assumed that the ODU links
   are pre-configured and using mechanisms such as WDM wavelength, which
   are outside the scope of this document.

2. Terminology

   Domain: defined as a collection of network elements within a common
   realm of address space or path computation responsibility [RFC5151]

   E-LINE: Ethernet Line

   EPL: Ethernet Private Line

   EVPL: Ethernet Virtual Private Line

   OTN: Optical Transport Network

   Service: A service in the context of this document can be considered
   as some form of connectivity between customer sites across the
   network operator's network [RFC8309]

   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.

   UNI: User Network Interface

   MDSC: Multi-Domain Service Coordinator

   CNC: Customer Network Controller

   PNC: Provisioning Network Controller

   MAC Bridging: Virtual LANs (VLANs) on IEEE 802.3 Ethernet network





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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 can be either an adaptation of a client layer into a
   server layer "(client -> server)" or switching at a given layer
   "([switching])". Multi-layer switching is indicated by two layer
   switching with client/server adaptation: "([client] -> [server])".

   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 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 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.








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3.2. JSON code

   This document provides some detailed JSON code examples to describe
   how the YANG models being developed by IETF (TEAS and CCAMP WG in
   particular) can be used.

   The examples are provided using JSON because JSON code is easier for
   humans to read and write.

   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 an "-",
   followed by "-ID". For example, the mnemonic identifier for node S3
   would be S3-NODE-ID.

   JSON language does not support the insertion of comments that have
   been instead found to be useful when writing the examples. 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.

   In order 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 node S3 (S3-NODE-ID) has been assumed to
   be "10.0.0.3" and would be shown in the JSON code example using the
   two JSON name/value pair:

      "// te-node-id": "S3-NODE-ID",

      "te-node-id": "10.0.0.3",






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   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.

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 providing transport services to an IP customer network
   through eight access links:



































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                ........................
   ..........   :                      :
            :   :   Network domain 1   :   .............
   Customer:   :                      :   :           :
    domain :   :     S1 -------+      :   :  Network  :
           :   :    /           \     :   :  domain 3 :   ..........
       R1 ------- S3 ----- S4    \    :   :           :   :
           :   :    \        \    S2 --------+        :   :Customer
           :   :     \        \    |  :   :   \       :   : domain
           :   :      S5       \   |  :   :    \      :   :
       R2 ------+    /  \       \  |  :   :    S31 --------- R7
           :   : \  /    \       \ |  :   :   /   \   :   :
           :   :  S6 ---- S7 ---- S8 ------ S32   S33 ------ R8
           :   : /        |       |   :   : / \   /   :   :.......
       R3 ------+         |       |   :   :/   S34    :          :
           :   :..........|.......|...:   /    /      :          :
   ........:              |       |      /:.../.......:          :
                           |       |     /    /                   :
                ...........|.......|..../..../...                 :
                :          |       |   /    /   :    ..............
                : Network  |       |  /    /    :    :
                : domain 2 |       | /    /     :    :Customer
                :         S11 ---- S12   /      :    : domain
                :        /          | \ /       :    :
                :     S13     S14   | S15 ------------- R4
                :     |  \   /   \  |    \      :    :
                :     |   S16     \ |     \     :    :
                :     |  /         S17 -- S18 --------- R5
                :     | /             \   /     :    :
                :    S19 ---- S20 ---- S21 ------------ R6
                :                               :    :
                :...............................:    :.............

                        Figure 1 - Reference network

   This document assumes that all the transport network switching nodes
   Si are OTN switching nodes capable of switching in the electrical
   domain (ODU switching) and that 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. Different technologies can be
   used at the access links (e.g., Ethernet, STM-n, OTN).

   It is also assumed that, within the transport network, the
   physical/optical interconnections supporting the Si-Sj OTN links (up



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   to the OTU4 trail), are pre-configured using mechanisms which are
   outside the scope of this document and are not exposed at the MPIs to
   the MDSC.

   The transport domain control architecture, shown in Figure 2, follows
   the ACTN architecture and framework document [RFC8453], and
   functional components:

                           --------------
                          |              |
                          |     CNC      |
                          |              |
                           --------------
                                 |
             ....................|....................... CMI
                                 |
                          ----------------
                         |                |
                         |      MDSC      |
                         |                |
                          ----------------
                            /   |    \
                           /    |     \
            ............../.....|......\................ MPIs
                         /      |       \
                        /   ----------   \
                       /   |   PNC2   |   \
                      /     ----------     \
             ----------         |           \
            |   PNC1   |      -----          \
             ----------     (       )      ----------
                 |         (         )    |   PNC3   |
               -----      (  Network  )    ----------
             (       )    (  Domain 2 )        |
            (         )    (         )       -----
           (  Network  )    (       )      (       )
           (  Domain 1 )      -----       (         )
            (         )                  (  Network  )
             (       )                   (  Domain 3 )
               -----                      (         )
                                           (       )
                                             -----

                     Figure 2 - Controlling Hierarchy



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   The ACTN framework facilitates the detachment of the network and
   service control from the underlying technology and helps the customer
   express the network as desired by business needs. Therefore, care
   must be taken to keep a minimal dependency on the CMI (or no
   dependency at all) with respect to the network domain technologies.
   The MPI instead requires some specialization according to the domain
   technology.

   This document assumes that the CNC controls the customer IP network
   and requests, at the CMI, transport connectivity between IP routers.
   The MDSC coordinates, via three MPIs, the control of a multi-domain
   transport network through three PNCs.

   The control interfaces within the scope of this document are the
   three MPIs, while the control interface(s) between the CNC and the IP
   routers is outside the scope of this document. It is also assumed
   that the CMI allows the CNC to provide all the information that is
   required by the MDSC to properly configure the transport connectivity
   requested by the customer.

   In case the CNC requests transport connectivity between IP routers
   attached to different transport domains (e.g., between R1 and R5),
   the MDSC coordinates the setup of a multi-domain end-to-end OTN
   connection across multiple PNCs (e.g., PNC1, PNC2 and PNC3 in in
   Figure 2) as well as the configuration of the client signal mapping
   at the PNCs controlling the edge domains (e.g., PNC1 and PNC2 in
   Figure 2).

4.1.1. Single-Domain Scenario

   In case the CNC requests transport connectivity between IP routers
   attached to the same transport domain (e.g., between R1 and R3 in
   Figure 1), the MDSC can request the PNC controlling that domain
   (e.g., PNC1 in Figure 2) to setup an intra-domain end-to-end OTN
   connection and configure the client signal mapping.

   Alternatively, the MDSC can just configure the client signal mapping
   and let the PNC take decisions about how to implement the service
   (e.g., setting up the intra-domain end-to-end OTN connection).

4.2. Topology Abstractions

   Abstraction provides a selective method for representing connectivity
   information within a domain. There are multiple methods to abstract a



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   network topology. This document assumes the abstraction method
   defined in [RFC7926]:

     "Abstraction is the process of applying the policy to the available
     TE information within a domain, to produce selective information
     that represents the potential ability to connect across the domain.
     Thus, abstraction does not necessarily offer all possible
     connectivity options, but 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 topology:

   o  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;

   o  Black topology: The entire domain network is abstracted as a
      single virtual node with the access/egress links without
      disclosing any node internal connectivity information;

   o  Grey topology: This abstraction level is between black topology
      and white topology from a granularity point of view. This is an
      abstraction of TE tunnels for all pairs of border nodes. We may
      further differentiate from a perspective of how to abstract
      internal TE resources between the pairs of border nodes:

       - Grey topology type A: border nodes with TE links between them
          in a full mesh fashion;

       - Grey topology type B: border nodes with some internal
          abstracted nodes and abstracted links.

   Each PNC should provide the MDSC with a topology abstraction of the
   domain's network topology.





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   Each PNC provides topology abstraction of its own domain topology
   independently from each other, and therefore it is possible that
   different PNCs provide different types of topology abstractions.

   The MPI operates on the abstract topology regardless of, and
   independently from, the type of abstraction provided by the PNC.

   To analyze how the MPI operates on abstract topologies independently
   from the topology abstraction provided by each PNC and, therefore,
   that different PNCs can provide different topology abstractions, that
   the following examples are assumed:

   o  PNC1 provides a black topology abstraction which exposes at MPI1 a
      single virtual node (representing the whole network domain 1).

   o  PNC2 provides a black topology abstraction which exposes at MPI2 a
      single virtual node (representing the whole network domain 2).

   o  PNC3 provides a white topology abstraction which exposes at MPI3
      all the physical nodes and links within network domain 3.

   The MDSC should be capable of stitching together each abstracted
   topology to build its own view of the multi-domain network topology.
   The process may require suitable oversight, including administrative
   configuration and trust models, but this is out of scope for this
   document.

   The MDSC can also provide topology abstraction of its own view of the
   multi-domain network topology at its CMIs depending on the customers'
   needs: it can provide different types of topology abstractions at
   different CMIs.

4.3. Service Configuration

   In the following scenarios, it is assumed that the CNC is capable of
   requesting service connectivity from the MDSC to support IP routers
   connectivity.

   The type of services could depend on the type of physical links (e.g.
   OTN link, ETH link or SDH link) between the routers and transport
   network.

   The control of different adaptations inside IP routers, Ri (PKT ->
   foo) and Rj (foo -> PKT), are assumed to be performed by means that



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   are not under the control of, and not visible to, the MDSC nor to the
   PNCs. Therefore, these mechanisms are outside the scope of this
   document.

   It is just assumed that the CNC is capable of requesting the proper
   configuration of the different adaptation functions inside the
   customer's IP routers, by means which 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-configured 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).

   To setup a 10Gb IP link between R1 and R5, an ODU2 end-to-end
   connection needs be created in the data plane between R1 and R5,
   through transport nodes S3, S1, S2, S31, S33, S34, S15 and S18 which
   belong to different PNC domains (multi-domain service request):

      R1 ([PKT] -> ODU2), S3 ([ODU2]), S1 ([ODU2]), S2 ([ODU2]),
      S31 ([ODU2]), S33 ([ODU2]), S34 ([ODU2]),
      S15 ([ODU2]), S18 ([ODU2]), R5 (ODU2 -> [PKT])

   It is assumed that, at the CMI, the CNC requests, using mechanisms
   which are outside the scope of this document, the MDSC to setup of an
   ODU2 transit service between the access links on S3 and S8 and that
   the MDSC understands that it shall setup an ODU2 segment connection
   between the access links on S3 and S18, which belongs to different
   PNC domains (multi-domain service request).

   To setup of a 10Gb IP link between R1 and R3, an ODU2 end-to-end
   connection needs are created in the data plane between R1 and R3,
   through transport 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])




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   Since the CNC is not aware of the transport network controlling
   hierarchy, the mechanisms used by the CNC to request at the CMI the
   MDSC to setup an ODU2 transit service are independent on whether the
   service request is single-domain or multi-domain.

   Based on the assumption above, the MDSC understands that it shall
   setup an ODU2 segment connection between the access links on S3 and
   S6, which belong to the same PNC domain (single-domain service
   request) and it can just pass the request at the MPI to PNC1 to setup
   a single-domain ODU2 segment connection between its access links on
   S3 and S6.

4.3.2. EPL over ODU

   The physical links interconnecting the IP routers and the transport
   network can be Ethernet physical links.

   To setup a 10Gb IP link between R1 and R5, an EPL service needs to be
   created between R1 and R5, supported by an ODU2 end-to-end connection
   in the data plane between transport nodes S3 and S18, through
   transport 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), R5 (ETH -> [PKT])

   Based on the assumptions described in section 4.3.1, the CNC requests
   at the CMI the MDSC to setup an EPL service between the access links
   on S3 and S8 and the MDSC understands that it shall setup an ODU2
   end-to-end connection between nodes S3 and S18, which belongs to
   different PNC domains (multi-domain service request). The MDSC also
   understands how the adaptation functions inside nodes S3 and S18
   (i.e., S3 (ETH -> [ODU2]), S18 ([ODU2] -> ETH), S18 (ETH -> [ODU2])
   and S3 ([ODU2] -> ETH)) should be configured.

   To setup a 10Gb IP link between R1 and R3, an EPL service needs to be
   created between R1 and R3, supported by an ODU2 end-to-end connection
   in the data plane between transport nodes S3 and S6, through the
   transport node S5, which belong to the same PNC domain (single-domain
   service request):

      R1 ([PKT] -> ETH), S3 (ETH -> [ODU2]), S5 ([ODU2]),
      S6 ([ODU2] -> ETH), R3 (ETH-> [PKT])



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   As described in section 4.3.1, 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, the MDSC understands that it shall
   setup an EPL service between the access links on S3 and S6, which
   belong to the same PNC domain (single-domain service request) and it
   can just pass the request at the MPI to PNC1 to setup a single-domain
   EPL service its access links on S3 and S6. In this case, PNC1 can
   take care of setting up the single-domain ODU2 end-to-end connection
   between nodes S3 and S6 as well as of configuring the adaptation
   functions on these edge nodes.

4.3.3. Other OTN Clients Services

   [ITU-T G.709] defines mappings of different 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.).

   The physical links interconnecting the IP routers and the transport
   network can be any of these types.

   In order to setup a 10Gb IP link between R1 and R5 using, for example
   SDH physical links between the IP routers and the transport network,
   an STM-64 Private Line service needs to be created between R1 and R5,
   supported by an ODU2 end-to-end connection in the data plane between
   transport nodes S3 and S18, through transport 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), R5 (STM-64 -> [PKT])

   Based on the assumptions described in section 4.3.1, the CNC requests
   the CMI the MDSC to setup an STM-64 Private Line service between the
   access links on S3 and S8 and the MDSC understands what to do as
   described in section 4.3.2 (multi-domain service request).

   To setup a 10Gb IP link between R1 and R3), an STM-64 Private Line
   service needs to be created between R1 and R3 (single-domain service
   request):




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      R1 ([PKT] -> STM-64), S3 (STM-64 -> [ODU2]), S5 ([ODU2]),
      S6 ([ODU2] -> STM-64), R3 (STM-64 -> [PKT])

   As described in section 4.3.1, the mechanisms used by the CNC at the
   CMI are independent on whether the service request is single-domain
   or multi-domain.

   As described in section 4.3.2, the MDSC can just pass the request at
   the MPI to PNC1 to setup a single-domain STM-64 Private Line service
   between it access links on S3 and S6.

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.

   To setup two 1Gb IP links between R1 to R3 and between R1 and R5, two
   EVPL services need to be created, supported by two ODU0 end-to-end
   connections in the data plane respectively between transport nodes S3
   and S6, through transport node S5, which belong ot the same PNC
   domain (single-domain service request) and between transport nodes S3
   and S18, through transport nodes S1, S2, S31, S33, S34 and S15, which
   belong to different PNC domains (multi-domain service request):

      R1 ([PKT] -> VLAN), S3 (VLAN -> [ODU0]), S1 ([ODU0]),
      S2 ([ODU0]), S31 ([ODU0]), S33 ([ODU0]), S34 ([ODU0]),
      S15 ([ODU0]), S18 ([ODU0] -> VLAN), R5 (VLAN -> [PKT])

      R1 ([PKT] -> VLAN), S3 (VLAN -> [ODU0]), S5 ([ODU0]),
      S6 ([ODU0] -> VLAN), R3 (VLAN -> [PKT])

   Since the two EVPL services are sharing 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 4.3.1, the CNC requests
   at the CMI the MDSC to setup these EVPL services and the MDSC
   understands what to do as described in section 4.3.2.






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4.3.5. EVPLAN and EVPTree Services

   When the physical links interconnecting the IP routers and the
   transport network are Ethernet links, multipoint Ethernet services
   (e.g., EPLAN and EPTree) can also be supported. It is also possible
   that multiple Ethernet services (e.g., EVPL, EVPLAN and EVPTree)
   share the same physical link using different VLANs.

   Note - it is assumed that EPLAN and EPTree services can be supported
   by configuring EVPLAN and EVPTree with port mapping.

   Since this EVPLAN/EVPTree service can share the same Ethernet
   physical links between IP routers and transport nodes (e.g., with the
   EVPL services described in section 4.3.4), a different VLAN ID (e.g.,
   30) can be associated with this EVPLAN/EVPTree service.

   In order to setup an IP subnet between R1, R2, R3 and R5, an
   EVPLAN/EVPTree service needs to be created, supported by two ODUflex
   end-to-end connections respectively between S3 and S6, crossing
   transport node S5, and between S3 and S18, crossing transport nodes
   S1, S2, S31, S33, S34 and S15 which belong to different PNC domains.

   Some MAC Bridging capabilities are also required on some nodes at the
   edge of the transport network: for example, Ethernet Bridging
   capabilities can be configured in nodes S3 and S6:

   o  MAC Bridging in node S3 is needed to select, based on the MAC
      Destination Address, whether received Ethernet frames should be
      forwarded to R1 or to the ODUflex terminating on node S6 or to the
      other ODUflex terminating on node S18;

   o  MAC bridging function in node S6 is needed to select, based on the
      MAC Destination Address, whether received Ethernet frames should
      be sent to R2 or to R3 or to the ODUflex terminating on node S3.

   In order to support an EVPTree service instead of an EVPLAN,
   additional configuration of the Ethernet Bridging capabilities on the
   nodes at the edge of the transport network is required.

   The traffic flows between R1 and R3, between R3 and R5 and between R1
   and R5 can be summarized as:






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      R1 ([PKT] -> VLAN), S3 (VLAN -> [MAC] -> [ODUflex]),
      S5 ([ODUflex]), S6 ([ODUflex] -> [MAC] -> VLAN),
      R3 (VLAN -> [PKT])

      R3 ([PKT] -> VLAN), S6 (VLAN -> [MAC] -> [ODUflex]),
      S5 ([ODUflex]), S3 ([ODUflex] -> [MAC] -> [ODUflex]),
      S1 ([ODUflex]), S2 ([ODUflex]), S31 ([ODUflex]),
      S33 ([ODUflex]), S34 ([ODUflex]),
      S15 ([ODUflex]), S18 ([ODUflex] -> VLAN), R5 (VLAN -> [PKT])

      R1 ([PKT] -> VLAN), S3 (VLAN -> [MAC] -> [ODUflex]),
      S1 ([ODUflex]), S2 ([ODUflex]), S31 ([ODUflex]),
      S33 ([ODUflex]), S34 ([ODUflex]),
      S15 ([ODUflex]), S18 ([ODUflex] -> VLAN), R5 (VLAN -> [PKT])

   As described in section 4.3.2, it is assumed that the CNC is capable,
   via the CMI, to request the setup of this EVPLAN/EVPTree service,
   providing all the information that the MDSC needs to understand that
   it need to request PNC1 to setup an ODUflex connection between nodes
   S3 and S6 (single-domain service request) and it also needs to
   coordinate the setup of a multi-domain ODUflex connection between
   nodes S3 and S16 as well as the MAC bridging and the adaptation
   functions on these edge nodes.

   In case the CNC needs the setup of an EVPLAN/EVPTree service only
   between R1, R2 and R3 (single-domain service request), it would
   request the setup of this service in the same way as before and the
   information provided at the CMI is sufficient for the MDSC to
   understand that this is a single-domain service request.

   The MDSC can then just request PNC1 to setup a single-domain
   EVPLAN/EVPTree service between nodes S3 and S6. PNC1 can take care of
   setting up the single-domain ODUflex end-to-end connection between
   nodes S3 and S6 as well as of configuring the MAC bridging and the
   adaptation functions on these edge nodes.

4.3.6. Dynamic Service Configuration

   Given the service established in the previous sections, there is a
   demand for an update of some service characteristics. A
   straightforward approach would be terminate the current service and
   replace with a new one. Another more advanced approach would be a
   dynamic configuration, in which case there will be no interruption
   for the connection.



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   An example application would be updating the SLA information for a
   certain connection. For example, an ODU transit connection is set up
   according to section 4.3.1, with the corresponding SLA level of 'no
   protection'. After the establishment of this connection, the user
   would like to enhance this service by providing a restoration after
   potential failure, and a request is generated on the CMI. In this
   case, after receiving the request, the MDSC would need to send an
   update message to the PNC, changing the SLA parameters in TE Tunnel
   model. Then the connection characteristic would be changed by PNC,
   and a notification would be sent to MDSC for acknowledgement.

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 or STM-64
   or 10GE.

   This configuration can be done a-priori by means outside the scope of
   this document. In this case, these links will appear at the MPI
   either as an ODU Link or as an STM-64 Link or as a 10GE Link
   (depending on the a-priori configuration) and will be controlled at
   the MPI as discussed in section 4.3.

   It is also possible not to configure these links a-priori and give
   the control to the MPI to decide, based on the service configuration,
   how to configure it.

   For example, if the physical link between R1 and S3 is a multi-
   functional access link while the physical links between R7 and S31
   and between R5 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 R7 or an EPL service between R1 and R5.

   The traffic flow between R1 and R7 can be summarized as:

      R1 ([PKT] -> STM-64), S3 (STM-64 -> [ODU2]), S1 ([ODU2]),
      S2 ([ODU2]), S31 ([ODU2] -> STM-64), R3 (STM-64 -> [PKT])

   The traffic flow between R1 and R5 can be summarized as:

      R1 ([PKT] -> ETH), S3 (ETH -> [ODU2]), S1 ([ODU2]),
      S2 ([ODU2]), S31 ([ODU2]), S33 ([ODU2]), S34 ([ODU2]),
      S15 ([ODU2]), S18 ([ODU2] -> ETH), R5 (ETH -> [PKT])




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   As described in section 4.3.2, it is assumed that the CNC is capable,
   via the CMI, to request the setup either an STM-64 Private Line
   service between R1 and R7 or an EPL service between R1 and R5,
   providing all the information that the MDSC needs to understand that
   it needs to coordinate the setup of a multi-domain ODU2 connection,
   either between nodes S3 and S31, or between nodes S3 and S18, as well
   as the adaptation functions on these edge nodes, and in particular
   whether the multi-function access link on between R1 and S3 should
   operate as an STM-64 or as a 10GE link.

4.5. Protection and Restoration Configuration

   Protection switching provides a pre-allocated survivability
   mechanism, typically provided via linear protection methods and would
   be configured to operate as 1+1 unidirectional (the most common OTN
   protection method), 1+1 bidirectional or 1:n bidirectional. This
   ensures fast and simple service survivability.

   Restoration methods would provide the capability to reroute and
   restore connectivity traffic around network faults, without the
   network penalty imposed with dedicated 1+1 protection schemes.

   This section describes only services which are protected with linear
   protection and with dynamic restoration.

   The MDSC needs to be capable of coordinating different PNCs to
   configure protection switching when requesting the setup of the
   protected connectivity services described in section 4.3.

   Since in these service examples, switching within the transport
   network domain is performed only in the OTN ODU layer. Also
   protection switching within the transport network domain can only be
   provided at the OTN ODU layer.

4.5.1. Linear Protection (end-to-end)

   In order to protect any service defined in section 4.3 from failures
   within the OTN multi-domain transport network, the MDSC should be
   capable of coordinating different PNCs to configure and control OTN
   linear protection in the data plane between nodes S3 and node S18.

   It is assumed that the OTN linear protection is configured to with
   1+1 unidirectional protection switching type, as defined in [ITU-T
   G.808.1] and [ITU-T G.873.1], as well as in [RFC4427].



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   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:

   o  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

   o  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

   The PNCs should be capable to report 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 (50ms recovery 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 any service defined in section 4.3 from failures within
   the OTN multi-domain transport network, the MDSC should be capable of




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   requesting each PNC to configure OTN intra-domain protection when
   requesting the setup of the ODU2 data plane connection segment.

   If PNC1 provides linear protection, the working and protection
   transport entities could be:

      Working transport entity:     S3, S1, S2

      Protection transport entity:  S3, S4, S8, S2

   If PNC2 provides linear protection, the working and protection
   transport entities could be:

      Working transport entity:     S15, S18

      Protection transport entity:  S15, S12, S17, S18

   If PNC3 provides linear protection, the working and protection
   transport entities could be:

      Working transport entity:     S31, S33, S34

      Protection transport entity:  S31, S32, S34

4.5.3. End-to-End Dynamic restoration

   To restore any service defined in section 4.3 from failures within
   the OTN multi-domain transport network, the MDSC should be capable of
   coordinating different PNCs to configure and control OTN end-to-end
   dynamic Restoration in the data plane between nodes S3 and node S18.
   For example, the MDSC can request the PNC1, PNC2 and PNC3 to create a
   service with no-protection, MDSC set the end-to-end service with the
   dynamic restoration.

         Working transport entity:     S3, S1, S2,
                                       S31, S33, S34,
                                       S15, S18

   When a link failure between S1 and s2 occurred in network domain 1,
   PNC1 does not restore the tunnel and send the alarm notification to
   the MDSC, MDSC will perform the end-to-end restoration.

         Restored transport entity:    S3, S4, S8,
                                       S12, S15, S18



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4.5.4. Segmented Dynamic Restoration

   To restore any service defined in section 4.3 from failures within
   the OTN multi-domain transport network, the MDSC should be capable of
   coordinating different PNCs to configure and control OTN segmented
   dynamic Restoration in the data plane between nodes S3 and node S18.

         Working transport entity:     S3, S1, S2,
                                       S31, S33, S34,
                                       S15, S18

   When a link failure between S1 and s2 occurred in network domain 1,
   PNC1 will restore the tunnel and send the alarm or tunnel update
   notification to the MDSC, MDSC will update the restored tunnel.

         Restored transport entity:    S3, S4, S8, S2
                                       S31, S33, S34,
                                       S15, S18

   When a link failure between network domain 1 and network domain 2
   occurred, PNC1 and PNC2 will send the alarm notification to the MDSC,
   MDSC will update the restored tunnel.

         Restored transport entity:    S3, S4, S8,
                                       S12, S15, S18

   In order to improve the efficiency of recovery, the controller can
   establish a recovery path in a concurrent way. When the recovery
   fails in one domain or one network element, the rollback operation
   should be supported.

   The creation of the recovery path by the controller can use the
   method of "make-before-break", in order to reduce the impact of the
   recovery operation on the services.

4.6. Service Modification and Deletion

   To be discussed in future versions of this document.

4.7. Notification

   To realize the topology update, service update and restoration
   function, following notification type should be supported.




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   1. Object create

   2. Object delete

   3. Object state change

   4. Alarm

   Because there are three types of topology abstraction type defined in
   section 4.2, the notification should also be abstracted. The PNC and
   MDSC should coordinate together to determine the notification policy,
   such as when an intra-domain alarm occurred, the PNC may not report
   the alarm but the service state change notification to the MDSC.

4.8. Path Computation with Constraint

   It is possible to have constraint during path computation procedure;
   typical cases include IRO/XRO and so on. This information is carried
   in the TE Tunnel model and used when there is a request with
   constraint. Consider the example in section 4.3.1. , the request can
   be a Tunnel from R1 to R5 with an IRO from S2 to S31, then qualified
   feedback would become:

   R1 ([PKT] -> ODU2), S3 ([ODU2]), S1 ([ODU2]), S2 ([ODU2]),
   S31 ([ODU2]), S33 ([ODU2]), S34 ([ODU2]),
   S15 ([ODU2]), S18 ([ODU2]), R5 (ODU2 -> [PKT])

   If the request covers the IRO from S8 to S12, then the above path
   would not be qualified, while a possible computation result may be:

   R1 ([PKT] -> ODU2), S3 ([ODU2]), S1 ([ODU2]), S2 ([ODU2]),
   S8 ([ODU2]), S12 ([ODU2]), S15 ([ODU2]), S18 ([ODU2]), R5 (ODU2 ->
   [PKT])

   Similarly, the XRO can be represented by the TE tunnel model as well.

   When there is a technology specific network (e.g., OTN), the
   corresponding technology (OTN) model should also be used to specify
   the tunnel information on MPI, with the constraint included in TE
   Tunnel model.







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5. YANG Model Analysis

   This section provides a high-level overview of how IETF YANG models
   can be used at the MPIs, between the MDSC and the PNCs, to support
   the scenarios described in section 4.

   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 coordinate different requests
   to different PNCs, via their own MPIs, 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

   Each PNC reports its respective abstract topology to the MDSC, as
   described in section 4.2.


























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5.1.1. Domain 1 Black Topology Abstraction

   PNC1 provides the required black topology abstraction, as described
   in section 4.2, to expose to the MDSC, at MPI1, one TE Topology
   instance for the ODU layer (MPI1 OTN Topology) containing only one
   abstract TE node (i.e., AN1) and only inter-domain and access
   abstract TE links (which represent the inter-domain and access
   physical links), as shown in Figure 3 below.

                   ...................................
                   :                                 :
                   :       +-----------------+       :
                   :       |                 |       :
           (R1)- - --------|                 |-------- - -(S31)
                   : AN1-1 |                 | AN1-2 :
                   :       |                 |       :
           (R2)- - --------|                 |       :
                   : AN1-3 |       AN1       |       :
                   :       |                 |       :
           (R3)- - --------|                 |-------- - -(S32)
                   : AN1-7 |                 | AN1-4 :
                   :       |                 |       :
                   :       +-----------------+       :
                   :          |          |           :
                   :    AN1-6 |          | AN1-5     :
                   :..........|..........|...........:

                              |          |
                            (S11)      (S12)

     Figure 3 - Abstract Topology exposed at MPI1 (MPI1 OTN Topology)

   As described in section 4.1, it is assumed that the physical links
   between the physical nodes are pre-configured and therefore PNC1
   exports at MPI1 one abstract TE Link, within the MPI1 OTN topology,
   for each OTU2 or OTU4 trail which support an abstract TE link in the
   MPI1 ODU Topology.










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                  ..................................
                  :                                :
                  :   ODU Abstract Topology @ MPI  :
                  :        Gotham City Area        :
                  :     Metro Transport Network    :
                  :                                :
                  :        +----+        +----+    :
                  :        |    |S1-1    |    |S2-1:
                  :        | S1 |--------| S2 |----- - -(S31)
                  :        +----+    S2-2+----+    :
                  :     S1-2/               |S2-3  :
                  :    S3-2/ Robinson Park  |      :
                  :    +----+   +----+      |      :
                  :    |    |3 1|    |      |      :
          (R1)- - -----| S3 |---| S4 |      |      :
                  :S3-1+----+   +----+      |      :
                  :   S3-4 \        \S4-2   |      :
                  :         \S5-1    \      |      :
                  :        +----+     \     |      :
                  :        |    |      \S8-3|      :
                  :        | S5 |       \   |      :
                  :        +----+ Metro  \  |S8-2  :
          (R2)- - ------  2/ E  \3 Main   \ |      :
                  :S6-1 \ /3 a E \1 Ring   \|      :
                  :    +----+s-n+----+   +----+    :
                  :    |    |t d|    |   |    |S8-1:
                  :    | S6 |---| S7 |---| S8 |----- - -(S32)
                  :    +----+4 2+----+3 4+----+    :
                  :     /         |        |       :
          (R3)- - ------     S7-4 |        | S8-5  :
                  :S6-2           |        |       :
                  :...............|........|.......:

                                  |        |
                                (S11)    (S12)

              Figure 4 - Physical Topology discovered by PNC1

   LTP mapping table:

   AN1-1 -> S3-1

   AN1-2 -> S2-1



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   AN1-3 -> S6-1

   AN1-4 -> S8-1

   AN1-5 -> S8-5

   AN1-6 -> S7-4

   AN1-7 -> S6-2

   Appendix B.1.1 provides the detailed JSON code example ("mpi1-otn-
   topology.json") describing how this ODU Topology is reported by the
   PNC, using the [TE-TOPO] and [OTN-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:

   o  YANG attributes which are outside the scope of this document are
      not shown

   o  The attributes describing the label restrictions are also not
      shown to simplify the JSON code example

   o  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, one TE Topology
   instance for the ODU layer (MPI2 OTN Topology) containing only one
   abstract node (i.e., AN2) and only inter-domain and access abstract
   TE links (which represent the inter-domain and access physical
   links).

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, one TE Topology
   instance for the ODU layer (MPI3 OTN Topology) containing one
   abstract TE node for each physical node and one abstract TE link for



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   each physical link (internal links, inter-domain links or access
   links).

5.1.4. Multi-domain Topology Stitching

   As assumed at the beginning of this section, MDSC does not have any
   knowledge of the topologies of each domain until each PNC reports its
   own abstraction topology, so the MDSC needs to merge together the
   abstract topologies provided by different PNCs, at the MPIs, to build
   its own topology view, as described in section 4.3 of [TE-TOPO].

   Given the topologies reported from multiple PNCs, the MDSC need to
   stitch the multi-domain topology and obtain the full map of topology.
   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 understand how to "stitch" together these inter-
   domain links.

   One possibility is to use the plug-id information, defined in [TE-
   TOPO]: two inter-domain links 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, or it can be discovered using 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 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



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   plug-id namespace is partitioned to avoid that different sources
   assign the same plug-id value to different inter-domain link. The
   encoding of the plug-id namespace within the plug-id value is
   implementation specific but needs to be consistent across all the
   PNCs.

   Another possibility is to pre-configure, either in the adjacent PNCs
   or in the MDSC, the association between the inter-domain link
   identifiers (topology-id, node-id and tp-id) assigned by the two
   adjacent PNCs to the same inter-domain link.

   This last scenario requires further investigation and will be
   discussed in a future version of this document.


































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                ........................
                :                      :
                :   Network domain 1   :   .............
                :   Grey Topology      :   :           :
                :     Abstraction      :   :  Network  :
                :                      :   :  domain 3 :
        (R1)- - -------+               :   :  (White)  :
                :       \      +--------------+        :
                :        \    /        :   :   \       :
                :         \  /         :   :    \      :
        (R2)- - --------- AN1 --+      :   :    S31 ---- - (R7)
                :         /|\    \     :   :   /   \   :   :
                :        / | \    +--------- S32   S33 - - (R8)
                :       /  |  \        :   :/  \   /   :
        (R3)- - -------+   |   +---+   :   /    S34    :
                :..........|.......|...:  /:   /       :
                           |       |     / :../........:
                           |       |    /    /
                ...........|.......|.../..../....
                :          |       |  /    /    :
                : Network  |       + /    /     :
                : domain 2 |      / /    /      :
                :          |     / /    /       :
                :          |    + / +--+        :
                :          |    |/ /         +--- - -(R4)
                : Black    +--- AN2 ---------+  :
                : Topology      | |             :
                : Abstraction   | +-------------- - -(R5)
                :               |               :
                :               +---------------- - -(R6)
                :                               :
                :...............................:

       Figure 5 - Multi-domain Abstract Topology discovered by MDSC

5.1.5. Access Links

   Access links in Figure 3 are shown as ODU Links: the modeling of the
   access links for other access technologies is currently an open
   issue.

   The modeling of the access link in case of non-ODU access technology
   has also an impact on the need to model ODU TTPs and layer transition



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   capabilities on the edge nodes (e.g., nodes S2, S3, S6 and S8 in
   Figure 3).

   If, for example, the physical NE S6 is implemented in a "pizza box",
   the data plane would have only set of ODU termination resources
   (where up to 2xODU4, 4xODU3, 20xODU2, 80xODU1, 160xODU0 and
   160xODUflex can be terminated). The traffic coming from each of the
   10GE access links can be mapped into any of these ODU terminations.

   Instead if, for example, the physical NE S6 can be implemented as a
   multi-board system where access links reside on different/dedicated
   access cards with a separated set of ODU termination resources (where
   up to 1xODU4, 2xODU3, 10xODU2, 40xODU1, 80xODU0 and 80xODUflex for
   each resource can be terminated). The traffic coming from one 10GE
   access links can be mapped only into the ODU terminations which
   reside on the same access card.

   The more generic implementation option for a physical NE (e.g., S6)
   would be the case is of a multi-board system with multiple access
   cards with separated sets of access links and ODU termination
   resources (where up to 1xODU4, 2xODU3, 10xODU2, 40xODU1, 80xODU0 and
   80xODUflex for each resource can be terminated). The traffic coming
   from each of the 10GE access links on one access card can be mapped
   only into any of the ODU terminations which reside on the same access
   card.

   In the last two cases, only the ODUs terminated on the same access
   card where the access links reside can carry the traffic coming from
   that 10GE access link. Terminated ODUs can instead be sent to any of
   the OTU4 interfaces

   In all these cases, terminated ODUs can be sent to any of the OTU4
   interfaces assuming the implementation is based on a non-blocking ODU
   cross-connect.

   If the access links are reported via MPI in some, still to be
   defined, client topology, it is possible to report each set of ODU
   termination resources as an ODU TTP within the ODU Topology of Figure
   3 and to use either the inter-layer lock-id or the transitional link,
   as described in sections 3.4 and 3.10 of [TE-TOPO], to correlate the
   access links, in the client topology, with the ODU TTPs, in the OTN
   topology, to which access link are connected to.





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5.2. YANG Models for Service Configuration

   The service configuration procedure is assumed to be initiated (step
   1 in Figure 6) at the CMI from CNC to MDSC. Analysis of the CMI
   models is (e.g., L1SM, L2SM, Transport-Service, VN, et al.) is
   outside the scope of this document.

   As described in section 4.3, 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 connection (or
   connection segment) 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 6 - Multi-domain Service Setup

   As an example, the objective in this section is to configure a
   transport service between R1 and R5. The cross-domain routing is
   assumed to be R1 <-> S3 <-> S2 <-> S31 <-> S33 <-> S34 <->S15 <-> S18
   <-> R5.

   According to the different client signal type, there is different
   adaptation required.



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   After receiving such request, MDSC determines the domain sequence,
   i.e., domain 1 <-> domain 2 <-> domain 3, with corresponding PNCs and
   inter-domain links (step 2 in Figure 6).

   As described in [PATH-COMPUTE], the domain sequence can be determined
   by running the MDSC own path computation on the MDSC internal
   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 6) 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 tunnel
   segments via tunnel model (including both TE tunnel model and OTN
   tunnel model), and request different PNCs to setup each intra-domain
   tunnel segment (steps 3, 3.1, 3.2 and 3.3 in Figure 6).

   Assume that each intra-domain tunnel segment can be set up
   successfully, and each PNC response to the MDSC respectively. Based
   on each segment, MDSC will take care of the configuration of both the
   intra-domain tunnel segment and inter-domain tunnel via corresponding
   MPI (via TE tunnel model and OTN tunnel model). More specifically,
   for the inter-domain configuration, the ts-bitmap and tpn attributes
   need to be configured using the OTN Tunnel model. Then the end-to-end
   OTN tunnel will be ready.

   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 in our example)
   and not on the PNCs of transit domain (e.g., PNC-2 in our example).
   An access link will be configured by MDSC after the OTN tunnel is set
   up. Access configuration is different and dependent on the different
   type of service. More details can be found in the following sections.

5.2.1. ODU Transit Service

   In this scenario, described in section 4.3.1, the access links are
   configured as ODU Links.

   Since it is assumed that the physical access links are pre-
   configured, each PNC exposes, at its MPI, one TE Link (called "ODU
   Link") for each of these physical access link. These links are
   reported, together with any other ODU internal or inter-domain link,
   within the OTN abstract topology exposed by each PNC, at its own MPI.




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   To setup this IP link, between R1 and R5, the CNC requests, at the
   CMI, the MDSC to setup an ODU transit service.

   From the topology information described in section 5.1 above, the
   MDSC understands that R1 is attached to the access link terminating
   on S3-1 LTP in the ODU Topology exposed by PNC1 and that R5 is
   attached to the access link terminating on AN2-1 LTP in the ODU
   Topology exposed by PNC2.

   MDSC would then request, at MPI1, the PNC1 to setup an ODU2 (Transit
   Segment) Tunnel with one primary path between S3-1 and S2-1 LTPs:

   o  Source and Destination TTPs are not specified (since it is a
      Transit Tunnel)

   o  Ingress and egress points are indicated in the route-object-
      include-exclude list of the explicit-route-objects of the primary
      path:

       o The first element references the access link terminating on
          S3-1 LTP

       o The last two element references respectively the inter-domain
          link terminating on S2-1 LTP and the data plane resources
          (i.e., the timeslots and the TPN, called "OTN Label") used by
          the ODU2 connection over that link.

   The configuration of the timeslots used by the ODU2 connection on the
   internal links within a PNC domain (i.e., on the internal links
   domain) 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 on node S31 within PNC3 domain).

   The MDSC, when coordinating the setup of a multi-domain ODU
   connection, also configures the data plane resources (i.e., the
   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 nodes
   terminating the inter-domain links (e.g., S2 and S31) from the OTN
   Topology information exposed, at the MPIs, by the PNCs controlling



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   the OTN physical nodes (e.g., PNC1 and PNC3 controlling the physical
   nodes S2 and S31 respectively).

   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.

   The Transport PNC performs path computation and sets up the ODU2
   cross-connections within the physical nodes S3, S5 and S6, as shown
   in section 4.3.1.

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.

   The Transport PNC reports the status of the created ODU2 (Transit
   Segment) Tunnel and its path within the ODU Topology as shown in
   Figure 7 below:


























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                   ..................................
                   :                                :
                   :   ODU Abstract Topology @ MPI  :
                   :                                :
                   :        +----+        +----+    :
                   :        |    |        |    |    :
                   :        | S1 |--------| S2 |- - - - -(R4)
                   :        +----+        +----+    :
                   :         /               |      :
                   :        /                |      :
                   :    +----+   +----+      |      :
                   :    |    |   |    |      |      :
           (R1)- - - - -  S3 |---| S4 |      |      :
                   :S3-1 <<= +   +----+      |      :
                   :       =        \        |      :
                   :       = \       \       |      :
                   :       == ---+    \      |      :
                   :        =    |     \     |      :
                   :        = S5 |      \    |      :
                   :        == --+       \   |      :
           (R2)- - - - -     =  \         \  |      :
                   :S6-1 \ / =   \         \ |      :
                   :    +--- =   +----+   +----+    :
                   :    |    =   |    |   |    |    :
                   :    | S6 = --| S7 |---| S8 |- - - - -(R5)
                   :    +--- =   +----+   +----+    :
                   :     /   =                      :
           (R3)- - - - -  <<==                      :
                   :S6-2                            :
                   :................................:

                       Figure 7 - ODU2 Transit Tunnel

5.2.2. EPL over ODU Service

   In this scenario, described in section 4.3.2, the access links are
   configured as Ethernet Links.

   To setup this IP link, between R1 and R5, the CNC requests, at the
   CMI, the MDSC to setup an EPL service.

   As described in section 5.1.5 above, it is not clear in this case how
   the Ethernet access links between the transport network and the IP
   router, are reported by the PNC to the MDSC.



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   If the 10GE physical links are not reported as ODU links within the
   OTN topology information, described in section 5.1.1 above than the
   MDSC will not have sufficient information to know that R1 and R5 are
   attached to the access links terminating on S3 and S6.

   Assuming that the MDSC knows how R1 and R3 are attached to the
   transport network, the MDSC would request the Transport PNC to setup
   an ODU2 end-to-end Tunnel between S3 and S6.

   This ODU Tunnel is setup between two TTPs of nodes S3 and S6. In case
   of nodes S3 and S6 support more than one TTP, the MDSC should decide
   which TTP to use.

   As discussed in 5.1.5, depending on the different hardware
   implementations of the physical nodes S3 and S6, not all the access
   links can be connected to all the TTPs. The MDSC should therefore
   select not only the optimal TTP but also a TTP that would allow the
   Tunnel to be used by the service.

   It is assumed that in case of node S3 or node S6 supports only one
   TTP, this TTP can be accessed by all the access links.

   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.

   Once the ODU2 Tunnel setup has been requested, unless there is a one-
   to-one relationship between the S3 and S6 TTPs and the Ethernet
   access links toward R1 and R3 (as in the case, described in section
   5.1.5, where the Ethernet access links reside on different/dedicated
   access card such that the ODU2 tunnel can only carry the Ethernet
   traffic from the only Ethernet access link on the same access card
   where the ODU2 tunnel is terminated), the MDSC also needs to request
   the setup of an EPL service from the access links on S3 and S6,
   attached to R1 and R3, and this ODU2 Tunnel.

   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-SVC] YANG
   model at MPI1.






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5.2.3. Other OTN Client Services

   In this scenario, the access links are configured as one of the OTN
   clients (e.g., STM-64) links.

   As described in section 4.3.3, the CNC needs to setup an STM-64
   Private Link service, supporting an IP link, between R1 and R3 and
   requests this service at the CMI to the MDSC.

   MDSC needs to setup an STM-64 Private Link service between R1 and R3
   supported by an ODU2 end-to-end connection between S3 and S6.

   As described in section 5.1.5 above, it is not clear in this case how
   the access links (e.g., the STM-N access links) between the transport
   network and the IP router, are reported by the PNC to the MDSC.

   The same issues, as described in section 5.2.2, apply here:

   o  the MDSC needs to understand that R1 and R3 are connected, thought
      STM-64 access links, with S3 and S6

   o  the MDSC needs to understand which TTPs in S3 and S6 can be
      accessed by these access links

   o  the MDSC needs to configure the private line service from these
      access links through the ODU2 tunnel

5.2.4. EVPL over ODU Service

   In this scenario, the access links are configured as Ethernet links,
   as described in section 5.2.2 above.

   As described in section 4.3.4, the CNC needs to setup EVPL services,
   supporting IP links, between R1 and R3, as well as between R1 and R4
   and requests these services at the CMI to the MDSC.

   MDSC needs to setup two EVPL services, between R1 and R3, as well as
   between R1 and R4, supported by ODU0 end-to-end connections between
   S3 and S6 and between S3 and S2 respectively.

   As described in section 5.1.5 above, it is not clear in this case how
   the Ethernet access links between the transport network and the IP
   router, are reported by the PNC to the MDSC.




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   The same issues, as described in section 5.1.5 above, apply here:

   o  the MDSC needs to understand that R1, R3 and R4 are connected,
      thought the Ethernet access links, with S3, S6 and S2

   o  the MDSC needs to understand which TTPs in S3, S6 and S2 can be
      accessed by these access links

   o  the MDSC needs to configure the EVPL services from these access
      links through the ODU0 tunnels

   In addition, the MDSC needs to get the information that the access
   links on S3, S6 and S2 are capable of supporting EVPL (rather than
   just EPL) as well as to coordinate the VLAN configuration, for each
   EVPL service, on these access links (this is a similar issue as the
   timeslot configuration on access links discussed in section 4.3.1
   above).

5.3. YANG Models for Protection Configuration

5.3.1. Linear Protection (end-to-end)

   To be discussed in future versions of this document.

5.3.2. Segmented Protection

   To be discussed in future versions of this document.

6. Security Considerations

   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.

   This document analyses the applicability of the YANG models being
   defined by the IETF to support OTN single and multi-domain scenarios
   There are no specific new security considerations introduced by this
   document.

   In OTN 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.



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7. IANA Considerations

   This document requires no IANA actions.

8. References

8.1. Normative References

   [RFC7926] Farrel, A. et al., "Problem Statement and Architecture for
             Information Exchange between Interconnected Traffic-
             Engineered Networks", BCP 206, RFC 7926, July 2016.

   [RFC4427] Mannie, E., Papadimitriou, D., "Recovery (Protection and
             Restoration) Terminology for Generalized Multi-Protocol
             Label Switching (GMPLS)", RFC 4427, March 2006.

   [RFC8453] Ceccarelli, D., Lee, Y. et al., "Framework for Abstraction
             and Control of TE Networks (ACTN)", RFC8453, August 2018.

   [ITU-T G.709] ITU-T Recommendation G.709 (06/16), "Interfaces for the
             optical transport network", June 2016.

   [ITU-T G.808.1] ITU-T Recommendation G.808.1 (05/14), "Generic
             protection switching - Linear trail and subnetwork
             protection", May 2014.

   [ITU-T G.873.1] ITU-T Recommendation G.873.1 (05/14), "Optical
             transport network (OTN): Linear protection", May 2014.

   [TE-TOPO] Liu, X. et al., "YANG Data Model for TE Topologies", draft-
             ietf-teas-yang-te-topo, work in progress.

   [OTN-TOPO] Zheng, H. et al., "A YANG Data Model for Optical Transport
             Network Topology", draft-ietf-ccamp-otn-topo-yang, work in
             progress.

   [CLIENT-TOPO]  Zheng, H. et al., "A YANG Data Model for Client-layer
             Topology", draft-zheng-ccamp-client-topo-yang, work in
             progress.

   [TE-TUNNEL] Saad, T. et al., "A YANG Data Model for Traffic
             Engineering Tunnels and Interfaces", draft-ietf-teas-yang-
             te, work in progress.




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   [PATH-COMPUTE] Busi, I., Belotti, S. et al, "Yang model for
             requesting Path Computation", draft-ietf-teas-yang-path-
             computation, work in progress.

   [OTN-TUNNEL]   Zheng, H. et al., "OTN Tunnel YANG Model", draft-ietf-
             ccamp-otn-tunnel-model, work in progress.

   [CLIENT-SVC]   Zheng, H. et al., "A YANG Data Model for Optical
             Transport Network Client Signals", draft-zheng-ccamp-otn-
             client-signal-yang, work in progress.

8.2. Informative References

   [RFC5151] Farrel, A. et al., "Inter-Domain MPLS and GMPLS Traffic
             Engineering --Resource Reservation Protocol-Traffic
             Engineering (RSVP-TE) Extensions", RFC 5151, February 2008.

   [RFC6898] Li, D. et al., "Link Management Protocol Behavior
             Negotiation and Configuration Modifications", RFC 6898,
             March 2013.

   [RFC8040] Bierman, A. et al., "RESTCONF Protocol", RFC 8040, January
             2017.

   [RFC8309] Wu, Q. et al., "Service Models Explained", RFC 8309,
             January 2018.

   [ACTN-YANG] Zhang, X. et al., "Applicability of YANG models for
             Abstraction and Control of Traffic Engineered Networks",
             draft-zhang-teas-actn-yang, work in progress.

   [RFC-FOLD]  Watsen, K. et al., "Handling Long Lines in Artwork in
             Internet-Drafts and RFCs", work in progress

   [ONF TR-527] ONF Technical Recommendation TR-527, "Functional
             Requirements for Transport API", June 2016.

   [ONF GitHub] ONF Open Transport (SNOWMASS)
             https://github.com/OpenNetworkingFoundation/Snowmass-
             ONFOpenTransport







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9. 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, Hans Bjursrom and Italo Busi for having initiated
   the work on gap analysis for transport NBI and having provided
   foundations work for the development of this document.

   The authors would like to thank the authors of the TE Topology and
   Tunnel YANG models [TE-TOPO] 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 document was prepared using 2-Word-v2.0.template.dot.
























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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.  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
   draft-kwatsen-netmod-artwork-folding. 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:

                       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   MAY              MAY                     MUST




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   of YANG data



   Our 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. It can be
   found at: https://github.com/GianmarcoBruno/json-yang/

A.2.  Comments in JSON fragments

   We found 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. "// __REFERENCES__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.3.  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 3without impacting the validation process, these
   comments will be automatically removed from the JSON-file that will
   be validate.

A.4.  Validation of JSON fragments: why not using a 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).









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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 [RFC-
   FOLD].

B.1.  JSON Examples for Topology Abstractions

B.1.1.   JSON Code: mpi1-otn-topology.json

   This is the JSON code reporting the OTN Topology @ MPI:




































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   ========== NOTE: '\\' line wrapping per BCP XX (RFC XXXX) ===========

   {
     "// __TITLE__": "ODU Black Topology @ MPI1",
     "// __LAST_UPDATE__": "October 18, 2018",
     "// __MISSING_ATTRIBUTES__": true,
     "// __REFERENCE_DRAFTS__": {
       "ietf-routing-types@2017-12-04": "rfc8294",
       "ietf-otn-types@2017-10-30": "draft-ietf-ccamp-otn-tunnel-model-\
   \01",
       "ietf-network@2018-02-26": "rfc8345",
       "ietf-network-topology@2018-02-26": "rfc8345",
       "ietf-te-types@2018-06-12": "draft-ietf-teas-yang-te-15",
       "ietf-te-topology@2018-06-15": "draft-ietf-teas-yang-te-topo-18",
       "ietf-otn-topology@2017-10-30": "draft-ietf-ccamp-otn-topo-yang-\
   \02"
     },
     "// __RESTCONF_OPERATION__": {
       "operation": "GET",
       "url": "http://{{PNC1-ADDR}}/restconf/data/ietf-network:networks"
     },
     "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:provider-id": 201,
           "ietf-te-topology:client-id": 300,
           "ietf-te-topology:te-topology-id": "otn-black-topology",
           "// ietf-te-topology:te": "presence container requires: prov\
   \ider, client and te-topology-id",
           "ietf-te-topology:te": {
             "name": "OTN Black Topology @ MPI1"
           },
           "// ietf-network:node": "Access LTPs to be reviewed in a fut\
   \ure update",
           "ietf-network:node": [
             {
               "// __NODE__:__DESCRIPTION__": {



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                 "name": "AN1",
                 "identifier": "10.0.0.1",
                 "type": "Abstract Node",
                 "physical node(s)": "whole network domain 1"
               },
               "node-id": "10.0.0.1",
               "ietf-te-topology:te-node-id": "10.0.0.1",
               "ietf-te-topology:te": {
                 "te-node-attributes": {
                   "name": "AN11",
                   "admin-status": "up",
                   "// __DISCUSS__ is-abstract": "To be discussed with \
   \TE Topology authors",
                   "// __DISCUSS__ underlay-topology": "To be discussed\
   \ with TE Topology authors"
                 },
                 "oper-status": "up",
                 "// __DISCUSS__ tunnel-termination-point": []
               },
               "ietf-network-topology:termination-point": [
                 {
                   "// __DESCRIPTION__:__LTP__": {
                     "name": "AN1-1 LTP",
                     "link type(s)": "OTU-2",
                     "physical node": "S3",
                     "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",
                     "admin-status": "up",
                     "// __DISCUSS__ interface-switching-capability": "\
   \See Link attributes (teNodeId/10.0.0.1/teLinkId/1)",
                     "// __DISCUSS__ inter-domain-plug-id": "Access Lin\
   \k",
                     "// __COMMENT__ inter-layer-lock-id": "Empty: OTN \
   \Links are pre-configured",
                     "oper-status": "up",
                     "// __DISCUSS__ ietf-otn-topology:supported-payloa\
   \d-types": "List of ODU clients?",
                     "// __DISCUSS__ ietf-otn-topology:client-facing": \



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   \true
                   }
                 },
                 {
                   "// __DESCRIPTION__:__LTP__": {
                     "name": "AN1-2 LTP",
                     "link type(s)": "OTU-4",
                     "physical node": "S2",
                     "unnumberd/ifIndex": 1,
                     "port type": "inter-domain port",
                     "connected to": "S31"
                   },
                   "tp-id": "2",
                   "ietf-te-topology:te-tp-id": 2,
                   "ietf-te-topology:te": {
                     "name": "AN1-2 LTP",
                     "admin-status": "up",
                     "// __DISCUSS__ interface-switching-capability": "\
   \See Link attributes (teNodeId/10.0.0.1/teLinkId/2)",
                     "// __DISCUSS__ inter-domain-plug-id": "Inter-doma\
   \in Link",
                     "oper-status": "up",
                     "// __DISCUSS__ ietf-otn-topology:supported-payloa\
   \d-types": "Empty? (inter-domain OTN link)",
                     "// __DEFAULT__ ietf-otn-topology:client-facing": \
   \false
                   }
                 },
                 {
                   "// __DESCRIPTION__:__LTP__": {
                     "name": "AN1-3 LTP",
                     "link type(s)": "OTU-2",
                     "physical node": "S6",
                     "unnumberd/ifIndex": 1,
                     "port type": "tributary port",
                     "connected to": "R2"
                   },
                   "tp-id": "3",
                   "ietf-te-topology:te-tp-id": 3,
                   "ietf-te-topology:te": {
                     "name": "AN1-3 LTP",
                     "admin-status": "up",
                     "// __DISCUSS__ interface-switching-capability": "\
   \See Link attributes (teNodeId/10.0.0.1/teLinkId/3)",



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                     "// __DISCUSS__ inter-domain-plug-id": "Access Lin\
   \k",
                     "oper-status": "up",
                     "// __DISCUSS__ ietf-otn-topology:supported-payloa\
   \d-types": "List of ODU clients?",
                     "// __DISCUSS__ ietf-otn-topology:client-facing": \
   \true
                   }
                 },
                 {
                   "// __DESCRIPTION__:__LTP__": {
                     "name": "AN1-4 LTP",
                     "link type(s)": "OTU-4",
                     "physical node": "S8",
                     "unnumberd/ifIndex": 1,
                     "port type": "inter-domain port",
                     "connected to": "S32"
                   },
                   "tp-id": "4",
                   "ietf-te-topology:te-tp-id": 4,
                   "ietf-te-topology:te": {
                     "name": "AN1-4 LTP",
                     "admin-status": "up",
                     "// __DISCUSS__ interface-switching-capability": "\
   \See Link attributes (teNodeId/10.0.0.1/teLinkId/4)",
                     "// __DISCUSS__ inter-domain-plug-id": "Inter-doma\
   \in Link",
                     "oper-status": "up",
                     "// __DISCUSS__ ietf-otn-topology:supported-payloa\
   \d-types": "Empty? (inter-domain OTN link)",
                     "// __DEFAULT__ ietf-otn-topology:client-facing": \
   \false
                   }
                 },
                 {
                   "// __DESCRIPTION__:__LTP__": {
                     "name": "AN1-5 LTP",
                     "link type(s)": "OTU-4",
                     "physical node": "S8",
                     "unnumberd/ifIndex": 5,
                     "port type": "inter-domain port",
                     "connected to": "S12"
                   },
                   "tp-id": "5",



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                   "ietf-te-topology:te-tp-id": 5,
                   "ietf-te-topology:te": {
                     "name": "AN1-5 LTP",
                     "admin-status": "up",
                     "// __DISCUSS__ interface-switching-capability": "\
   \See Link attributes (teNodeId/10.0.0.1/teLinkId/5)",
                     "// __DISCUSS__ inter-domain-plug-id": "Inter-doma\
   \in Link",
                     "oper-status": "up",
                     "// __DISCUSS__ ietf-otn-topology:supported-payloa\
   \d-types": "Empty? (inter-domain OTN link)",
                     "// __DEFAULT__ ietf-otn-topology:client-facing": \
   \false
                   }
                 },
                 {
                   "// __DESCRIPTION__:__LTP__": {
                     "name": "AN1-6 LTP",
                     "link type(s)": "OTU-4",
                     "physical node": "S7",
                     "unnumberd/ifIndex": 4,
                     "port type": "inter-domain port",
                     "connected to": "S11"
                   },
                   "tp-id": "6",
                   "ietf-te-topology:te-tp-id": 6,
                   "ietf-te-topology:te": {
                     "name": "AN1-6 LTP",
                     "admin-status": "up",
                     "// __DISCUSS__ interface-switching-capability": "\
   \See Link attributes (teNodeId/10.0.0.1/teLinkId/6)",
                     "// __DISCUSS__ inter-domain-plug-id": "Inter-doma\
   \in Link",
                     "oper-status": "up",
                     "// __DISCUSS__ ietf-otn-topology:supported-payloa\
   \d-types": "Empty? (inter-domain OTN link)",
                     "// __DEFAULT__ ietf-otn-topology:client-facing": \
   \false
                   }
                 },
                 {
                   "// __DESCRIPTION__:__LTP__": {
                     "name": "AN1-7 LTP",
                     "link type(s)": "OTU-2",



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                     "physical node": "S6",
                     "unnumberd/ifIndex": 2,
                     "port type": "tributary port",
                     "connected to": "R3"
                   },
                   "tp-id": "7",
                   "ietf-te-topology:te-tp-id": 7,
                   "ietf-te-topology:te": {
                     "name": "AN1-7 LTP",
                     "admin-status": "up",
                     "// __DISCUSS__ interface-switching-capability": "\
   \See Link attributes (teNodeId/10.0.0.1/teLinkId/7)",
                     "// __DISCUSS__ inter-domain-plug-id": "Access Lin\
   \k",
                     "oper-status": "up",
                     "// __DISCUSS__ ietf-otn-topology:supported-payloa\
   \d-types": "List of ODU clients?",
                     "// __DISCUSS__ ietf-otn-topology:client-facing": \
   \true
                   }
                 }
               ]
             }
           ],
           "// ietf-network-topology:link": "Access links to be reviewe\
   \d in a future update",
           "ietf-network-topology:link": [
             {
               "// __DESCRIPTION__:__LINK__": {
                 "name": "Access Link from AN1-1",
                 "type": "access link",
                 "physical link": "Link from S3-1 to R1"
               },
               "link-id": "teNodeId/10.0.0.1/teLinkId/1",
               "ietf-te-topology:te": {
                 "te-link-attributes": {
                   "name": "Access Link from AN1-1",
                   "// __DISCUSS__ access-type": "Can we assume point-t\
   \o-point as the default value?",
                   "access-type": "point-to-point",
                   "// __COMMENT__ external-domain": "Empty: the plug-i\
   \d is used instead of this container",
                   "// __DISCUSS__ is-abstract": "To be discussed with \
   \TE Topology authors",



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                   "// __DISCUSS__ underlay": "To be discussed with TE \
   \Topology authors",
                   "admin-status": "up",
                   "interface-switching-capability": [
                     {
                       "switching-capability": "ietf-te-types:switching\
   \-otn",
                       "encoding": "ietf-te-types:lsp-encoding-oduk",
                       "max-lsp-bandwidth": [
                         {
                           "priority": 0,
                           "// __DISCUSS__ te-bandwidth": "ODU2"
                         }
                       ]
                     }
                   ],
                   "// __COMMENT__ label-restrictions": "Not described \
   \in this JSON example",
                   "// __DISCUSS__ link-protection-type": "Can we assum\
   \e unprotected as the default value?",
                   "link-protection-type": "unprotected",
                   "max-link-bandwidth": {
                     "// __DISCUSS__ te-bandwidth": "1xODU2"
                   },
                   "max-resv-link-bandwidth": {
                     "// __DISCUSS__ te-bandwidth": "1xODU2"
                   },
                   "unreserved-bandwidth": [
                     {
                       "priority": 0,
                       "// __DISCUSS__ te-bandwidth": "1xODU2"
                     }
                   ]
                 },
                 "oper-status": "up",
                 "// __EMPTY__ is-transitional": "It is not a transitio\
   \nal link",
                 "// __DISCUSS__ underlay ": "To be discussed with TE T\
   \opology authors"
               },
               "source": {
                 "source-node": "10.0.0.1",
                 "source-tp": 1
               },



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               "// __EMPTY__ destination": "access link"
             },
             {
               "// __DESCRIPTION__:__LINK__": {
                 "name": "Inter-domain Link from AN1-2",
                 "type": "inter-domain link",
                 "physical link": "Link from S2-1 to S31"
               },
               "link-id": "teNodeId/10.0.0.1/teLinkId/2",
               "ietf-te-topology:te": {
                 "te-link-attributes": {
                   "name": "Inter-domain Link from AN1-2",
                   "// __DISCUSS__ access-type": "Can we assume point-t\
   \o-point as the default value?",
                   "access-type": "point-to-point",
                   "// __DISCUSS__ is-abstract": "To be discussed with \
   \TE Topology authors",
                   "// __DISCUSS__ underlay": "To be discussed with TE \
   \Topology authors",
                   "admin-status": "up",
                   "interface-switching-capability": [
                     {
                       "switching-capability": "ietf-te-types:switching\
   \-otn",
                       "encoding": "ietf-te-types:lsp-encoding-oduk",
                       "max-lsp-bandwidth": [
                         {
                           "priority": 0,
                           "// __DISCUSS__ te-bandwidth": "ODU4"
                         }
                       ],
                       "// __DISCUSS__ label-restrictions": "To be adde\
   \d?"
                     }
                   ],
                   "// __DISCUSS__ link-protection-type": "Can we assum\
   \e unprotected as the default value?",
                   "link-protection-type": "unprotected",
                   "max-link-bandwidth": {
                     "// __DISCUSS__ te-bandwidth": "1xODU4, ..."
                   },
                   "max-resv-link-bandwidth": {
                     "// __DISCUSS__ te-bandwidth": "1xODU4, ..."
                   },



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                   "unreserved-bandwidth": [
                     {
                       "priority": 0,
                       "// __DISCUSS__ te-bandwidth": "1xODU4, ..."
                     }
                   ]
                 },
                 "oper-status": "up",
                 "// __EMPTY__ is-transitional": "It is not a transitio\
   \nal link",
                 "// __DISCUSS__ underlay ": "To be discussed with TE T\
   \opology authors"
               },
               "source": {
                 "source-node": "10.0.0.1",
                 "source-tp": 2
               },
               "// __EMPTY__ destination": "inter-domain link"
             },
             {
               "// __DESCRIPTION__:__LINK__": {
                 "name": "Access Link from AN1-3",
                 "type": "access link",
                 "physical link": "Link from S6-1 to R2"
               },
               "link-id": "teNodeId/10.0.0.1/teLinkId/3",
               "ietf-te-topology:te": {
                 "te-link-attributes": {
                   "name": "Access Link from AN1-3",
                   "// __DISCUSS__ access-type": "Can we assume point-t\
   \o-point as the default value?",
                   "access-type": "point-to-point",
                   "// __DISCUSS__ is-abstract": "To be discussed with \
   \TE Topology authors",
                   "// __DISCUSS__ underlay": "To be discussed with TE \
   \Topology authors",
                   "admin-status": "up",
                   "interface-switching-capability": [
                     {
                       "switching-capability": "ietf-te-types:switching\
   \-otn",
                       "encoding": "ietf-te-types:lsp-encoding-oduk",
                       "max-lsp-bandwidth": [
                         {



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                           "priority": 0,
                           "// __DISCUSS__ te-bandwidth": "ODU2"
                         }
                       ],
                       "// __DISCUSS__ label-restrictions": "To be adde\
   \d?"
                     }
                   ],
                   "// __DISCUSS__ link-protection-type": "Can we assum\
   \e unprotected as the default value?",
                   "link-protection-type": "unprotected",
                   "max-link-bandwidth": {
                     "// __DISCUSS__ te-bandwidth": "1xODU2"
                   },
                   "unreserved-bandwidth": [
                     {
                       "priority": 0,
                       "// __DISCUSS__ te-bandwidth": "1xODU2"
                     }
                   ],
                   "max-resv-link-bandwidth": {
                     "// __DISCUSS__ te-bandwidth": "1xODU2"
                   }
                 },
                 "oper-status": "up",
                 "// __EMPTY__ is-transitional": "It is not a transitio\
   \nal link",
                 "// __DISCUSS__ underlay ": "To be discussed with TE T\
   \opology authors"
               },
               "source": {
                 "source-node": "10.0.0.1",
                 "source-tp": 3
               },
               "// __EMPTY__ destination": "access link"
             },
             {
               "// __DESCRIPTION__:__LINK__": {
                 "name": "Inter-domain Link from AN1-4",
                 "type": "inter-domain link",
                 "physical link": "Link from S8-1 to S32"
               },
               "link-id": "teNodeId/10.0.0.1/teLinkId/4",
               "ietf-te-topology:te": {



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                 "te-link-attributes": {
                   "name": "Inter-domain Link from AN1-4",
                   "// __DISCUSS__ access-type": "Can we assume point-t\
   \o-point as the default value?",
                   "access-type": "point-to-point",
                   "// __DISCUSS__ is-abstract": "To be discussed with \
   \TE Topology authors",
                   "// __DISCUSS__ underlay": "To be discussed with TE \
   \Topology authors",
                   "admin-status": "up",
                   "interface-switching-capability": [
                     {
                       "switching-capability": "ietf-te-types:switching\
   \-otn",
                       "encoding": "ietf-te-types:lsp-encoding-oduk",
                       "max-lsp-bandwidth": [
                         {
                           "priority": 0,
                           "// __DISCUSS__ te-bandwidth": "ODU4"
                         }
                       ],
                       "// __DISCUSS__ label-restrictions": "To be adde\
   \d?"
                     }
                   ],
                   "// __DISCUSS__ link-protection-type": "Can we assum\
   \e unprotected as the default value?",
                   "link-protection-type": "unprotected",
                   "max-link-bandwidth": {
                     "// __DISCUSS__ te-bandwidth": "1xODU4, ..."
                   },
                   "unreserved-bandwidth": [
                     {
                       "priority": 0,
                       "// __DISCUSS__ te-bandwidth": "1xODU4, ..."
                     }
                   ],
                   "max-resv-link-bandwidth": {
                     "// __DISCUSS__ te-bandwidth": "1xODU4, ..."
                   }
                 },
                 "oper-status": "up",
                 "// __EMPTY__ is-transitional": "It is not a transitio\
   \nal link",



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                 "// __DISCUSS__ underlay ": "To be discussed with TE T\
   \opology authors"
               },
               "source": {
                 "source-node": "10.0.0.1",
                 "source-tp": 4
               },
               "// __EMPTY__ destination": "inter-domain link"
             },
             {
               "// __DESCRIPTION__:__LINK__": {
                 "name": "Inter-domain Link from AN1-5",
                 "type": "inter-domain link",
                 "physical link": "Link from S8-5 to S12"
               },
               "link-id": "teNodeId/10.0.0.1/teLinkId/5",
               "ietf-te-topology:te": {
                 "te-link-attributes": {
                   "name": "Inter-domain Link from AN1-5",
                   "// __DISCUSS__ access-type": "Can we assume point-t\
   \o-point as the default value?",
                   "access-type": "point-to-point",
                   "// __DISCUSS__ is-abstract": "To be discussed with \
   \TE Topology authors",
                   "// __DISCUSS__ underlay": "To be discussed with TE \
   \Topology authors",
                   "admin-status": "up",
                   "interface-switching-capability": [
                     {
                       "switching-capability": "ietf-te-types:switching\
   \-otn",
                       "encoding": "ietf-te-types:lsp-encoding-oduk",
                       "max-lsp-bandwidth": [
                         {
                           "priority": 0,
                           "// __DISCUSS__ te-bandwidth": "ODU4"
                         }
                       ],
                       "// __DISCUSS__ label-restrictions": "To be adde\
   \d?"
                     }
                   ],
                   "// __DISCUSS__ link-protection-type": "Can we assum\
   \e unprotected as the default value?",



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                   "link-protection-type": "unprotected",
                   "max-link-bandwidth": {
                     "// __DISCUSS__ te-bandwidth": "1xODU4, ..."
                   },
                   "max-resv-link-bandwidth": {
                     "// __DISCUSS__ te-bandwidth": "1xODU4, ..."
                   },
                   "unreserved-bandwidth": [
                     {
                       "priority": 0,
                       "// __DISCUSS__ te-bandwidth": "1xODU4, ..."
                     }
                   ]
                 },
                 "oper-status": "up",
                 "// __EMPTY__ is-transitional": "It is not a transitio\
   \nal link",
                 "// __DISCUSS__ underlay ": "To be discussed with TE T\
   \opology authors"
               },
               "source": {
                 "source-node": "10.0.0.1",
                 "source-tp": 5
               },
               "// __EMPTY__ destination": "inter-domain link"
             },
             {
               "// __DESCRIPTION__:__LINK__": {
                 "name": "Inter-domain Link from AN1-6",
                 "type": "inter-domain link",
                 "physical link": "Link from S7-4 to S11"
               },
               "link-id": "teNodeId/10.0.0.1/teLinkId/6",
               "ietf-te-topology:te": {
                 "te-link-attributes": {
                   "name": "Inter-domain Link from AN1-6",
                   "// __DISCUSS__ access-type": "Can we assume point-t\
   \o-point as the default value?",
                   "access-type": "point-to-point",
                   "// __DISCUSS__ is-abstract": "To be discussed with \
   \TE Topology authors",
                   "// __DISCUSS__ underlay": "To be discussed with TE \
   \Topology authors",
                   "admin-status": "up",



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                   "interface-switching-capability": [
                     {
                       "switching-capability": "ietf-te-types:switching\
   \-otn",
                       "encoding": "ietf-te-types:lsp-encoding-oduk",
                       "max-lsp-bandwidth": [
                         {
                           "priority": 0,
                           "// __DISCUSS__ te-bandwidth": "ODU4"
                         }
                       ],
                       "// __DISCUSS__ label-restrictions": "To be adde\
   \d?"
                     }
                   ],
                   "// __DISCUSS__ link-protection-type": "Can we assum\
   \e unprotected as the default value?",
                   "link-protection-type": "unprotected",
                   "max-link-bandwidth": {
                     "// __DISCUSS__ te-bandwidth": "1xODU4, ..."
                   },
                   "max-resv-link-bandwidth": {
                     "// __DISCUSS__ te-bandwidth": "1xODU4, ..."
                   },
                   "unreserved-bandwidth": [
                     {
                       "priority": 0,
                       "// __DISCUSS__ te-bandwidth": "1xODU4, ..."
                     }
                   ]
                 },
                 "oper-status": "up",
                 "// __EMPTY__ is-transitional": "It is not a transitio\
   \nal link",
                 "// __DISCUSS__ underlay ": "To be discussed with TE T\
   \opology authors"
               },
               "source": {
                 "source-node": "10.0.0.1",
                 "source-tp": 6
               },
               "// __EMPTY__ destination": "inter-domain link"
             },
             {



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               "// __DESCRIPTION__:__LINK__": {
                 "name": "Access Link from AN1-7",
                 "type": "access link",
                 "physical link": "Link from S6-2 to R3"
               },
               "link-id": "teNodeId/10.0.0.1teLinkId/7",
               "ietf-te-topology:te": {
                 "te-link-attributes": {
                   "name": "Access Link from AN1-7",
                   "// __DISCUSS__ access-type": "Can we assume point-t\
   \o-point as the default value?",
                   "access-type": "point-to-point",
                   "// __DISCUSS__ is-abstract": "To be discussed with \
   \TE Topology authors",
                   "// __DISCUSS__ underlay": "To be discussed with TE \
   \Topology authors",
                   "admin-status": "up",
                   "interface-switching-capability": [
                     {
                       "switching-capability": "ietf-te-types:switching\
   \-otn",
                       "encoding": "ietf-te-types:lsp-encoding-oduk",
                       "max-lsp-bandwidth": [
                         {
                           "priority": 0,
                           "// __DISCUSS__ te-bandwidth": "ODU2"
                         }
                       ],
                       "// __DISCUSS__ label-restrictions": "To be adde\
   \d?"
                     }
                   ],
                   "// __DISCUSS__ link-protection-type": "Can we assum\
   \e unprotected as the default value?",
                   "link-protection-type": "unprotected",
                   "max-link-bandwidth": {
                     "// __DISCUSS__ te-bandwidth": "1xODU2"
                   },
                   "max-resv-link-bandwidth": {
                     "// __DISCUSS__ te-bandwidth": "1xODU2"
                   },
                   "unreserved-bandwidth": [
                     {
                       "priority": 0,



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                       "// __DISCUSS__ te-bandwidth": "1xODU2"
                     }
                   ]
                 },
                 "oper-status": "up",
                 "// __EMPTY__ is-transitional": "It is not a transitio\
   \nal link",
                 "// __DISCUSS__ underlay ": "To be discussed with TE T\
   \opology authors"
               },
               "source": {
                 "source-node": "10.0.0.1",
                 "source-tp": 7
               },
               "// __EMPTY__ destination": "access 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 @ MPI:



















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   ========== NOTE: '\\' line wrapping per BCP XX (RFC XXXX) ===========

   {
     "// __TITLE__": "ODU2 Service Configuration @ MPI1",
     "// __LAST_UPDATE__": "October 22, 2018",
     "// __MISSING_ATTRIBUTES__": true,
     "// __REFERENCE_DRAFTS__": {
       "ietf-routing-types@2017-12-04": "rfc8294",
       "ietf-otn-types@2018-06-07": "draft-ietf-ccamp-otn-tunnel-model-\
   \02",
       "ietf-te-types@2018-07-01": "draft-ietf-teas-yang-te-16",
       "ietf-te@2018-07-01": "draft-ietf-teas-yang-te-16",
       "ietf-otn-tunnel@2018-06-07": "draft-ietf-ccamp-otn-tunnel-model\
   \-02"
     },
     "// __RESTCONF_OPERATION__": {
       "operation": "PUT",
       "url": "http://{{PNC1-ADDR}}/restconf/data/ietf-te:te"
     },
     "ietf-te:te": {
       "tunnels": {
         "tunnel": [
           {
             "name": "mpi1-odu2-service",
             "// identifier": "ODU2-SERVICE-TUNNEL-ID @ MPI1",
             "identifier": 1,
             "description": "ODU2 Service implemented by ODU2 OTN Tunne\
   \l Segment @ MPI1",
             "// encoding and switching-type": "ODU",
             "encoding": "ietf-te-types:lsp-encoding-oduk ",
             "switching-type": "ietf-te-types:switching-otn",
             "// source": "None: transit tunnel segment",
             "// destination": "None: transit tunnel segment",
             "// src-tp-id": "None: transit tunnel segment",
             "// dst-tp-id": "None: transit tunnel segment",
             "// ietf-otn-tunnel:src-client-signal": "None: ODU transit\
   \ tunnel segment",
             "// ietf-otn-tunnel:dst-client-signal": "None: ODU transit\
   \ tunnel segment",
             "bidirectional": true,
             "// protection": "No protection",
             "// __ DEFAULT __ protection": {
               "// __ DEFAULT __ enable": false
             },



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             "// restoration": "No restoration",
             "// __ DEFAULT __ restoration": {
               "// __ DEFAULT __ enable": false
             },
             "// 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:odu-type": "ietf-otn-types:prot-ODU2"
             },
             "// hierarchical-link": "None: transit tunnel segment",
             "p2p-primary-paths": {
               "p2p-primary-path": [
                 {
                   "name": "mpi1-odu2-service-primary-path",
                   "path-scope": "ietf-te-types:path-scope-segment",
                   "// te-bandwidth": "None: only the tunnel bandwidth \
   \needs to be specified in transport applications",
                   "explicit-route-objects": {
                     "route-object-include-exclude": [
                       {
                         "// comment": "Tunnel hand-off OTU2 ingress in\
   \terface (S3-1)",
                         "index": 1,
                         "explicit-route-usage": "ietf-te-types:route-i\
   \nclude-ero",
                         "num-unnum-hop": {
                           "// node-id": "AN1 Node",
                           "node-id": "10.0.0.1",
                           "// link-tp-id": "AN1-1 LTP",
                           "link-tp-id": 1,
                           "hop-type": "STRICT",
                           "direction": "INCOMING"
                         }
                       },
                       {
                         "// comment": "Tunnel hand-off ODU2 ingress la\
   \bel (ODU2 over OTU2) at S3-1",
                         "index": 2,
                         "explicit-route-usage": "ietf-te-types:route-i\
   \nclude-ero",



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                         "label-hop": {
                           "te-label": {
                             "// __ DISCUSS __ odu-label": "How are HO-\
   \ODU (ODUk over OTUk) label represented?",
                             "// __ DISCUSS __ direction": "Check with \
   \TE Tunnel authors",
                             "direction": "FORWARD "
                           }
                         }
                       },
                       {
                         "// comment": "Tunnel hand-off OTU4 egress int\
   \erface (S2-1)",
                         "index": 3,
                         "explicit-route-usage": "ietf-te-types:route-i\
   \nclude-ero",
                         "num-unnum-hop": {
                           "// node-id": "AN1 Node",
                           "node-id": "10.0.0.1",
                           "// link-tp-id": "AN1-2 LTP",
                           "link-tp-id": 1,
                           "hop-type": "STRICT",
                           "direction": "OUTGOING"
                         }
                       },
                       {
                         "// comment": "Tunnel hand-off ODU2 egress lab\
   \el (ODU2 over OTU4) at S2-1",
                         "index": 4,
                         "explicit-route-usage": "ietf-te-types:route-i\
   \nclude-ero",
                         "label-hop": {
                           "te-label": {
                             "ietf-otn-tunnel:tpn": 1,
                             "ietf-otn-tunnel:tsg": "ietf-otn-types:tsg\
   \-1.25G",
                             "ietf-otn-tunnel:ts-list": "1-8",
                             "// __ DISCUSS __ direction": "Check with \
   \TE Tunnel authors",
                             "direction": "FORWARD "
                           }
                         }
                       }
                     ]



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                   }
                 }
               ]
             }
           }
         ]
       }
     }
   }

B.2.2.   JSON Code: mpi1-odu2-tunnel-config.json

   The JSON code for this use case will be added in a future version of
   this document

   An incomplete version is located on GitHub at:

   https://github.com/danielkinguk/transport-nbi

B.2.3.   JSON Code: mpi1-epl-service-config.json

   The JSON code for this use case will be added in a future version of
   this document

   An incomplete version is located on GitHub at:

   https://github.com/danielkinguk/transport-nbi




















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   Authors' Addresses

   Italo Busi (Editor)
   Huawei

   Email: italo.busi@huawei.com


   Daniel King (Editor)
   Lancaster University

   Email: d.king@lancaster.ac.uk


   Haomian Zheng (Editor)
   Huawei

   Email: zhenghaomian@huawei.com


   Yunbin Xu (Editor)
   CAICT

   Email: xuyunbin@ritt.cn


   Yang Zhao
   China Mobile

   Email: zhaoyangyjy@chinamobile.com


   Sergio Belotti
   Nokia

   Email: sergio.belotti@nokia.com


   Gianmarco Bruno
   Ericsson

   Email: gianmarco.bruno@ericsson.com





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   Young Lee
   Huawei

   Email: leeyoung@huawei.com


   Victor Lopez
   Telefonica

   Email: victor.lopezalvarez@telefonica.com


   Carlo Perocchio
   Ericsson

   Email: carlo.perocchio@ericsson.com


   Ricard Vilalta
   CTTC

   Email: ricard.vilalta@cttc.es

























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