Internet-Draft A YANG Data Model for Layer 1 Types November 2022
Lee, et al. Expires 18 May 2023 [Page]
Workgroup:
CCAMP Working Group
Internet-Draft:
draft-ietf-ccamp-l1csm-yang-19
Published:
Intended Status:
Standards Track
Expires:
Authors:
Y. Lee
Samsung
K. Lee
Korea Telecom
H. Zheng
Huawei Technologies
O. Gonzalez de Dios
Telefonica
D. Ceccarelli
Ericsson

A YANG Data Model for L1 Connectivity Service Model (L1CSM)

Abstract

This document provides a YANG Layer 1 Connectivity Service Model (L1CSM).

This model can be utilized by a customer network controller to initiate a connectivity service request as well as to retrieve service states for a Layer 1 network controller communicating with its customer network controller. This YANG model is NMDA-compliant.

Status of This Memo

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

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on 18 May 2023.

1. Introduction

This document provides a YANG Layer 1 (L1) Connectivity Service Model (L1CSM) which can be classified as Network Service YANG module per [RFC8199]. This model can be utilized by a customer network controller to initiate a connectivity service request as well as to retrieve service states for a Layer 1 network controller communicating with its customer network controller via a NETCONF [RFC8341] or a RESTCONF [RFC8040] interface.

[RFC4847] provides a framework and service level requirements for Layer 1 Virtual Private Networks (L1VPNs). It classifies the provision of L1VPN services into three service models (not to be confused with YANG models): the management-based service model, the signaling-based service model (Basic Mode), and the signaling and routing service model (Enhanced Mode).

In the management-based service model, customer management systems and provider management systems communicate with each other. Customer management systems access provider management systems to request layer 1 connection setup/deletion between a pair of CEs. Customer management systems may obtain additional information, such as resource availability information and monitoring information, from provider management systems. There is no control message exchange between a CE and PE.

In the signaling-based service model (Basic Model), the CE-PE interface's functional repertoire is limited to path setup signaling only. In the signaling and routing service model (Enhanced Mode), the CE-PE interface provides the signaling capabilities as in the Basic Mode, plus permits limited exchange of information between the control planes of the provider and the customer to help such functions as discovery of customer network routing information (i.e., reachability or TE information in remote customer sites), or parameters of the part of the provider's network dedicated to the customer.

The primary focus of this document is to describe L1CSM YANG model required for the instantiation of point-to-point L1 connectivity services, to provide layer 1 connectivity between two or more customer sites where the customer has some control over the establishment and type of the connectivity. The L1CSM specified in this document supports the point-to-point connectivity services defined in [RFC4847].

The YANG data model defined in Section 3 is consistent with the Service Attributes defined in [MEF63], with the exception of the Service Level Specification Service Attributes which are ouside the scope of this document.

This YANG model is NMDA-compliant.

1.1. Deployment Scenarios

Figure 1 depicts a deployment scenario of the L1CSM SDN control-based service model for an external customer instantiating L1 point-to-point connectivity to the provider.


                          +------------+
                          |  Customer  |
                          |   Service  |
                          |Orchestrator|
                          +------------+
                                 |
                   .. .. .. .. ..|.. .. .. .. .. ..
                  :              |                 :
                  :     +--------------------+     :
                  :     |                    |     :
                  :     |    +----------+    |     :
                  :     |    | Network  |    |     :
                  :     |    |   SDN    |    |     :
                  :     |    |Controller|    |     :
                  :     |    |/NMS/EMS  |    |     :
                  :     |    +----------+    |     :
                  :     |                    |     :
                  :     |                    |     :
        +----+    :   +----+    +----+    +----+   :   +----+
        | CE |----:---| PE |----| P  |----| PE |---:---| CE |
        +----+    :   +----+    +----+    +----+   :   +----+
                  :     |                    |     :
                  :     |                    |     :
                  :     +--------------------+     :
                  :     |                    |     :
                  :     |<-Provider network->|     :

              Customer                          Customer
              Interface                         Interface


Figure 1: L1CSM SDN Controller/EMS/NMS-Based Service Model: External Customer

With this scenario, the customer service orchestrator interfaces with the network SDN controller of the provider using Customer Service Model as defined in [RFC8309].

Figure 2 depicts another deployment scenario for internal customer (e.g., higher-layer service management departments) interfacing the layer 1 transport network department. With this scenario, a multi-service backbone is characterized such that each service department of a provider (e.g., L2/3 services) that receives the same provider's L1CSM service provides a different kind of higher-layer service. The customer receiving the L1CSM service (i.e., each service department) can offer its own services, whose payloads can be any layer (e.g., ATM, IP, TDM). The layer 1 transport network and each service network belong to the same organization, but may be managed separately. The Service SDN Controller is the control/management entity owned by higher-layer service department (e.g., L2/3 VPN) whereas the Network SDN Controller is the control/management entity responsible for Layer 1 connectivity service. The CEs in Figure 2 are L2/3 devices that interface with L1 PE devices.


                                +----------+
                                | Service  |
                                |   SDN    |
                                |Controller|
                                |/EMS/NMS  |
                                | for L2/3 |
                                +----------+
                                     |
                                     |
                                     |
                        +--------------------+
                        |                    |
                        |    +----------+    |
                        |    | Network  |    |
                        |    |   SDN    |    |
                        |    |Controller|    |
                        |    | /EMS/NMS |    |
                        |    | for L1CSM|    |
                        |    +----------+    |
                        |                    |
                        |                    |
        +----+        +----+    +----+    +----+      +----+
        | CE |--------| PE |----| P  |----| PE |------| CE |
        +----+        +----+    +----+    +----+      +----+
           |            |                    |          |
           |            |                    |          |
           |            +--------------------+          |
           |            |                    |          |
           |            |<------------------>|          |
           |               Provider Network             |
           |                  For Layer 1               |
           |<------------------------------------------>|
                          Provider Network for L2/3


Figure 2: L1CSM SDN Controller/EMS/NMS-Based Service Model: Internal Customer

The benefit is that the same layer 1 transport network resources are shared by multiple services. A large capacity backbone network (data plane) can be built economically by having the resources shared by multiple services usually with flexibility to modify topologies, while separating the control functions for each service department. Thus, each customer can select a specific set of features that are needed to provide their own service [RFC4847].

1.2. Terminology

Refer to [RFC4847] and [RFC5253] for the key terms used in this document.

The following terms are defined in [RFC7950] and are not redefined here:

  • client
  • server
  • augment
  • data model
  • data node

The following terms are defined in [RFC6241] and are not redefined here:

  • configuration data
  • state data

The terminology for describing YANG data models is found in [RFC7950].

1.3. Tree Diagram

A simplified graphical representation of the data model is used in Section 3 of this this document. The meaning of the symbols in these diagrams is defined in [RFC8340].

1.4. Prefixes in Data Node Names

In this document, names of data nodes and other data model objects are prefixed using the standard prefix associated with the corresponding YANG imported modules. The module ietf-layer1-types specified in [I-D.ietf-ccamp-layer1-types] and ietf-yang-types specified in [RFC6991] are imported in this module.


    +-------------+-------------------+------------------------------+
    | Prefix      | YANG module       |         Reference            |
    +-------------+-------------------+------------------------------+
    | l1csm       | ietf-l1csm        | RFCXXXX                      |
    | l1-types    | ietf-layer1-types | [RFCYYYY]                    |
    | yang        | ietf-yang-types   | [RFC6991]                    |
    +-------------+-------------------+------------------------------+

Note: The RFC Editor will replace XXXX with the number assigned to the RFC once this document becomes an RFC. The RFC Editor will replace YYYY with the number assigned to the RFC once [I-D.ietf-ccamp-layer1-types] becomes an RFC.

1.5. Abbreviations

L1VC Layer 1 Virtual Connection

UNI User Network Interface

PE Provider Edge

CE Customer Edge

EP End Point

P Protocol

C Coding

O Optical Interface

2. L1CSM YANG Model Overview

The L1CSM YANG data model describes the layer 1 connectivity services following the convention defined in [MEF63] which includes the description of User Network Interface (UNI) access characteristics and L1 virtual connection (L1VC) service characteristics:


    +--rw l1-connectivity
      +--rw access
      |  +--rw unis
      |     +--rw uni* [id]
      |        +--rw id         string
      |        .......................................
      +--rw services
         +--rw service* [service-id]
            +--rw service-id    string
            ..........................................

The UNI access characteristics can be specified using either the definitions in [MEF63], which are based on the 3-tuple includes protocol, coding and optical-interface, or the definitions in [I-D.ietf-ccamp-layer1-types], which are based on the client signals in [ITU-T_G.709]:


    +--rw (uni-access-type)?
       +--:(mef)
       |  +--rw protocol             identityref
       |  +--rw coding               identityref
       |  +--rw optical-interface    identityref
       +--:(itu)
          +--rw client-signal        identityref

The L1VC service characteristics are described by references to the two end points of the point-to-point connectivity:


    +--rw endpoint-1
    |  +--rw id     string
    |  +--rw uni    -> /l1-connectivity/access/unis/uni/id
    +--rw endpoint-2
       +--rw id     string
       +--rw uni    -> /l1-connectivity/access/unis/uni/id

3. L1CSM YANG Model (Tree Structure)


module: ietf-l1csm
  +--rw l1-connectivity
     +--rw access
     |  +--rw unis
     |     +--rw uni* [uni-id]
     |        +--rw uni-id                     string
     |        +--rw (uni-access-type)?
     |           +--:(mef)
     |           |  +--rw protocol             identityref
     |           |  +--rw coding               identityref
     |           |  +--rw optical-interface    identityref
     |           +--:(itu)
     |              +--rw client-signal        identityref
     +--rw services
        +--rw service* [service-id]
           +--rw service-id    string
           +--rw endpoint-1
           |  +--rw endpoint-id    string
           |  +--rw uni
           |          -> /l1-connectivity/access/unis/uni/uni-id
           +--rw endpoint-2
              +--rw endpoint-id    string
              +--rw uni
                      -> /l1-connectivity/access/unis/uni/uni-id


4. L1CSM YANG Code

<CODE BEGINS>file "ietf-l1csm@2022-10-14.yang"
module ietf-l1csm {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-l1csm";
  prefix "l1csm";

  import ietf-layer1-types {
    prefix "l1-types";
    reference
      "RFCYYYY: A YANG Data Model for Layer 1 Types";
  }
  // Note: The RFC Editor will replace XXXX/YYYY with the number
  // assigned to the RFCs once this draft becomes an RFC.

  organization
    "Internet Engineering Task Force (IETF) CCAMP WG";

  contact
    "WG Web: <https://datatracker.ietf.org/wg/ccamp/>
     WG List: <mailto:ccamp@ietf.org>

     Editor:  Young Lee
              <mailto:younglee.tx@gmail.com>

     Editor:  KwangKoog Lee
              <mailto:kwangkoog.lee@kt.com>

     Editor:  Haomian Zheng
              <mailto:zhenghaomian@huawei.com>

     Editor:  Oscar Gonzalez de Dios
              <mailto:oscar.gonzalezdedios@telefonica.com>

     Editor:  Daniele Ceccarelli
              <mailto:daniele.ceccarelli@ericsson.com>";

  description
    "This module describes L1 connectivity service based on MEF 63:
     Subscriber Layer 1 Service Attribute Technical Specification.
     Refer to MEF 63 for all terms and the original references
     used in the module.

     Copyright (c) 2022 IETF Trust and the persons identified as
     authors of the code.  All rights reserved.

     Redistribution and use in source and binary forms, with or
     without modification, is permitted pursuant to, and subject
     to the license terms contained in, the Revised BSD License
     set forth in Section 4.c of the IETF Trust's Legal Provisions
     Relating to IETF Documents
     (https://trustee.ietf.org/license-info).

     This version of this YANG module is part of RFC XXXX; see
     the RFC itself for full legal notices.";

  revision "2022-11-10" {
    description
      "Initial revision.";
    reference
      "RFC XXXX: A Yang Data Model for L1 Connectivity Service Model
       (L1CSM)";
  }

  /*
   * Groupings
   */

  grouping protocol-coding-optical-interface {
    description
      "The 3-tuple <p,c,o> where p:protocol type;
       c:coding function; o:optical interface function.

       Valid combinations are defined in Tables 4, 5, 6 and 7
       of MEF 63.";
    reference
      "MEF63: Subscriber Layer 1 Service Attributes";

    leaf protocol {
      type identityref {
        base l1-types:protocol;
      }
      mandatory true;
      description
        "The protocol being used at the UNI.";
    }
    leaf coding {
      type identityref {
        base l1-types:coding-func;
      }
      mandatory true;
      description
        "The coding function being used at the UNI.";
    }
    leaf optical-interface {
      type identityref {
        base l1-types:optical-interface-func;
      }
      mandatory true;
      description
        "The optical interface function being used at the UNI.";
    }
  }

  grouping subscriber-l1vc-endpoint-attributes {
    description
      "Subscriber layer 1 connection endpoint attributes";
    reference
      "MEF63: Subscriber Layer 1 Service Attributes";

    container endpoint-1 {
      description
        "One end of UNI id's - string and id";
      leaf endpoint-id {
        type string;
        mandatory true;
        description
          "Subscriber end point ID of one end";
      }
      leaf uni {
        type leafref {
          path "/l1-connectivity/access/unis/uni/uni-id";
        }
        mandatory true;
        description
          "This is one end of subscriber L1VC end point ID value =
           UNI-1";
      }
    }
    container endpoint-2 {
      description
        "One end of UNI id's - string and id";
      leaf endpoint-id {
        type string;
        must '. != ../../endpoint-1/uni' {
          error-message
            "The two end points must not be equal to each other. ";
        }
        mandatory true;
        description
          "Subscriber end point ID of the other end";
      }
      leaf uni {
        type leafref {
          path "/l1-connectivity/access/unis/uni/uni-id";
        }
        mandatory true;
        description
          "This is one other end of subscriber L1VC end point
           ID value = UNI-2";
      }
    }
  }

  /*
   * Data nodes
   */

  container l1-connectivity {
    description
      "Serves as a top-level container for a list of layer 1
       connection services (l1cs)";
    container access {
      description
        "UNI configurations for access networks";
      container unis {
        description
          "The list of UNI's to be configured";
        list uni {
          key "uni-id";
          description
            "UNI identifier";
          leaf uni-id {
            type string;
            description "The UNI id of UNI Service Attributes";
          }
          choice uni-access-type {
            description
              "The UNI access type can be specified either by the
               protocol, coding function and optical interface
               function, defined in MEF, or by the client-signal,
               defined in ITU-T.";
            case mef {
              uses protocol-coding-optical-interface;
            }
            case itu {
              leaf client-signal {
                type identityref {
                  base l1-types:client-signal;
                }
                mandatory true;
                description
                  "The client signal being used at the UNI";
              }
            }
          }
        }
      }
    }
    container services {
      description
        "L1VC services";
      list service {
        key "service-id";
        description
          "A unique identifier of a subscriber L1VC service";
        leaf service-id {
          type string;
          description
            "A unique service identifier for subscriber L1VC.";
        }
        uses subscriber-l1vc-endpoint-attributes;
      } //end of service list
    } //end of service container
  } //service top container
}

<CODE ENDS>

5. Security Considerations

The YANG module specified in this document defines a schema for data that is designed to be accessed via network management protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446].

The NETCONF access control model [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content.

A number of configuration data nodes defined in this document are writable/deletable (i.e., "config true") These data nodes may be considered sensitive or vulnerable in some network environments.

These are the subtrees and data nodes and their sensitivity/vulnerability:

unis:

- id

Service:

- service-id

- endpoint-1

- endpoint-2

- start-time

- time-interval

The security considerations spelled out in the YANG 1.1 specification [RFC7950] apply for this document as well.

6. IANA Considerations

This document registers the following URIs in the "ns" subregistry within the "IETF XML Registry" [RFC3688] as follows:


      URI: urn:ietf:params:xml:ns:yang:ietf-l1csm
      Registrant Contact: The IESG
      XML: N/A; the requested URI is an XML namespace.

This document registers following YANG modules in the YANG Module Names registry [RFC7950].


   name:         ietf-l1csm
   namespace:    urn:ietf:params:xml:ns:yang:ietf-l1csm
   prefix:       l1csm
   reference:    RFC XXXX

7. Acknowledgements

The authors would like to thank Tom Petch for his helpful comments and valuable contributions and Robert Wilton for his review that improved the model significantly.

8. Contributors

Italo Busi Huawei Technologies Email: Italo.Busi@huawei.com

Giuseppe Fioccola Huawei Technologies Email: giuseppe.fioccola@huawei.com

Dhruv Dhody Huawei Technologies Email: dhruv.ietf@gmail.com

9. References

9.1. Normative References

[I-D.ietf-ccamp-layer1-types]
Zheng, H. and I. Busi, "A YANG Data Model for Layer 1 Types", Work in Progress, Internet-Draft, draft-ietf-ccamp-layer1-types-14, , <https://www.ietf.org/archive/id/draft-ietf-ccamp-layer1-types-14.txt>.
[ITU-T_G.709]
International Telecommunication Union, "Interfaces for the optical transport network", ITU-T G.709, .
[MEF63]
Metro Ethernet Forum, "Subscriber Layer1 Service Attributes Technical Specification", MEF 63, .
[RFC3688]
Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, , <https://www.rfc-editor.org/info/rfc3688>.
[RFC6241]
Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, , <https://www.rfc-editor.org/info/rfc6241>.
[RFC6242]
Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, , <https://www.rfc-editor.org/info/rfc6242>.
[RFC6991]
Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, , <https://www.rfc-editor.org/info/rfc6991>.
[RFC7950]
Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, , <https://www.rfc-editor.org/info/rfc7950>.
[RFC8040]
Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, , <https://www.rfc-editor.org/info/rfc8040>.
[RFC8340]
Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, , <https://www.rfc-editor.org/info/rfc8340>.
[RFC8341]
Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, , <https://www.rfc-editor.org/info/rfc8341>.
[RFC8446]
Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, , <https://www.rfc-editor.org/info/rfc8446>.

9.2. Informative References

[RFC4847]
Takeda, T., Ed., "Framework and Requirements for Layer 1 Virtual Private Networks", RFC 4847, DOI 10.17487/RFC4847, , <https://www.rfc-editor.org/info/rfc4847>.
[RFC5253]
Takeda, T., Ed., "Applicability Statement for Layer 1 Virtual Private Network (L1VPN) Basic Mode", RFC 5253, DOI 10.17487/RFC5253, , <https://www.rfc-editor.org/info/rfc5253>.
[RFC8199]
Bogdanovic, D., Claise, B., and C. Moberg, "YANG Module Classification", RFC 8199, DOI 10.17487/RFC8199, , <https://www.rfc-editor.org/info/rfc8199>.
[RFC8309]
Wu, Q., Liu, W., and A. Farrel, "Service Models Explained", RFC 8309, DOI 10.17487/RFC8309, , <https://www.rfc-editor.org/info/rfc8309>.

Appendix A. JSON Example

This section provides a JSON example of the YANG module described in Section 4. This example configures one L1VC service with two UNIs that describe the UNI endpoints.


{
  "l1-connectivity": {
    "access": {
      "unis": {
        "uni": [
          {
            "id": "MTL-HQ-Node3-Slot2-Port1",
            "protocol": "ETH-10GigE_LAN ",
            "coding": "ETH-10GR-PCS-49 ",
            "optical_interface": "LR-PMD-clause-52 "
          },
          {
            "id": "MTL-STL-Node5-Slot4-Port3",
            "protocol": "ETH-10GigE_LAN ",
            "coding": "ETH-10GR-PCS-49 ",
            "optical_interface": "ER-PMD-clause-52 "
          }
        ]
      },
    },
    "services": {
      "service": [
        {
          "service-id": "Sub-L1VC-1867-LT-MEGAMART",
          "endpoint-1":
            {
              "id": "MTL-HQ_1867-MEGAMART",
              "uni": "MTL-HQ-Node3-Slot2-Port1"
            },
          "endpoint-2":
            {
              "id": "MTL-STL_1867-MEGAMART",
              "uni": "MTL-STL-Node5-Slot4-Port3"
            }
        }
      ]
    },
}


Authors' Addresses

Young Lee
Samsung
Samsung
Seoul
South Korea
KwangKoog Lee
Korea Telecom
South Korea
Haomian Zheng
Huawei Technologies
H1, Huawei Xiliu Beipo Village, Songshan Lake
Dongguan
Guangdong, 523808
China
Oscar Gonzalez de Dios
Telefonica
Daniele Ceccarelli
Ericsson