Internet-Draft AC Glue for VPN Models November 2023
Boucadair, et al. Expires 9 May 2024 [Page]
Workgroup:
OPSAWG
Internet-Draft:
draft-ietf-opsawg-ac-lxsm-lxnm-glue-00
Published:
Intended Status:
Standards Track
Expires:
Authors:
M. Boucadair, Ed.
Orange
R. Roberts
Juniper
S. B. Giraldo
Nokia
O. G. D. Dios
Telefonica

A YANG Data Model for Augmenting VPN Service and Network Models with Attachment Circuits

Abstract

The document specifies a module that updates existing service and network VPN modules with the required information to bind specific services to ACs that are created using the Attachment Circuit (AC) service model.

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 9 May 2024.

Table of Contents

1. Introduction

The document specifies a YANG module that updates existing service and network VPN modules with the required information to bind specific services to Attachment Circuits (ACs) that are created using the AC service model [I-D.boro-opsawg-teas-attachment-circuit], specifically the following modules are augmented:

2. Conventions and Definitions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

The meanings of the symbols in the YANG tree diagrams are defined in [RFC8340].

This document uses terms defined in [I-D.boro-opsawg-teas-attachment-circuit].

LxSM refers to both the L2SM and the L3SM.

LxNM refers to both the L2NM and the L3NM.

3. Sample Uses of the Data Models

3.1. ACs Terminated by One or Multiple Customer Edges (CEs)

Figure 1 depicts two target topology flavors that involve ACs. These topologies have the following characteristics:

  • A Customer Edges (CEs) can be either a physical device or a logical entity. Such logical entity is typically a software component (e.g., a virtual service function that is hosted within the provider's network or a third-party infrastructure). A CE is seen by the network as a peer SAP.

  • An AC service request may include one or multiple ACs, which may be associated to a single CE or multiple CEs.

  • CEs may be either dedicated to one single connectivity service or host multiple connectivity services (e.g., CEs with roles of service functions [RFC7665]).

  • A network provider may bind a single AC to one or multiple peer SAPs (e.g., CE#1 and CE#2 are tagged as peer SAPs for the same AC). For example, and as discussed in [RFC4364], multiple CEs can be attached to a PE over the same attachment circuit. This scenario is typically implemented when the layer 2 infrastructure between the CE and the network is a multipoint service.

  • A single CE may terminate multiple ACs, which can be associated with the same bearer or distinct bearers.

  • Customers may request protection schemes in which the ACs associated with their endpoints are terminated by the same PE (e.g., CE#3), distinct PEs (e.g., CE#34), etc. The network provider uses this request to decide where to terminate the AC in the network provider network and also whether to enable specific capabilities (e.g., Virtual Router Redundancy Protocol (VRRP)).

AC CE#1 AC CE#3 AC Network CE#2 AC CE#4 AC
Figure 1: Examples of ACs

3.2. Separate AC Provisioning vs. Actual Service Provisioning

The procedure to provision a service in a service provider network may depend on the practices adopted by a service provider. This includes the flow put in place for the provisioning of advanced network services and how they are bound to an attachment circuit. For example, a single attachment circuit may be used to host multiple connectivity services. In order to avoid service interference and redundant information in various locations, a service provider may expose an interface to manage ACs network-wide. Customers can then request a bearer or an attachment circuit to be put in place, and then refer to that bearer or AC when requesting services that are bound to the bearer or AC.

Figure 2 shows the positioning of the AC service model is the overall service delivery process.

Customer Customer Service Model e.g., slice-svc, ac-svc, and bearer-svc Service Orchestration Network Model e.g., l3vpn-ntw, sap, and ac-ntw Network Orchestration Network Configuration Model Domain Domain Orchestration Orchestration Device Configuration Model Config Manager NETCONF/CLI................ . | Bearer Bearer CE#1 Network CE#2 Site A Site B
Figure 2: An Example of AC Model Usage

4. Module Tree Structure

ACs created using the "ietf-ac-svc" module [I-D.boro-opsawg-teas-attachment-circuit] can be referenced in other modules (e.g., L2SM, L3SM, L2NM, L3NM, and Slicing). Some augmentations are required to that aim as shown in Figure 3.

module: ietf-ac-glue
  augment /l2vpn-svc:l2vpn-svc/l2vpn-svc:sites/l2vpn-svc:site
            /l2vpn-svc:site-network-accesses
            /l2vpn-svc:site-network-access:
    +--rw ac-ref*   ac-svc:attachment-circuit-reference
  augment /l3vpn-svc:l3vpn-svc/l3vpn-svc:sites/l3vpn-svc:site
            /l3vpn-svc:site-network-accesses
            /l3vpn-svc:site-network-access:
    +--rw ac-ref*   ac-svc:attachment-circuit-reference
  augment /l2nm:l2vpn-ntw/l2nm:vpn-services/l2nm:vpn-service
            /l2nm:vpn-nodes/l2nm:vpn-node/l2nm:vpn-network-accesses
            /l2nm:vpn-network-access:
    +--rw ac-ref*   ac-svc:attachment-circuit-reference
  augment /l3nm:l3vpn-ntw/l3nm:vpn-services/l3nm:vpn-service
            /l3nm:vpn-nodes/l3nm:vpn-node/l3nm:vpn-network-accesses
            /l3nm:vpn-network-access:
    +--rw ac-ref*   ac-svc:attachment-circuit-reference
Figure 3: AC Glue Tree Structure

5. The AC Glue ("ietf-ac-glue") YANG Module

<CODE BEGINS> file ietf-ac-glue@2023-07-13.yang
module ietf-ac-glue {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-ac-glue";
  prefix ac-glue;

  import ietf-l3vpn-svc {
    prefix l3vpn-svc;
    reference
      "RFC 8299: YANG Data Model for L3VPN Service Delivery";
  }
  import ietf-l2vpn-svc {
    prefix l2vpn-svc;
    reference
      "RFC 8466: A YANG Data Model for Layer 2 Virtual Private
                 Network (L2VPN) Service Delivery";
  }
  import ietf-l3vpn-ntw {
    prefix l3nm;
    reference
      "RFC 9182: A YANG Network Data Model for Layer 3 VPNs";
  }
  import ietf-l2vpn-ntw {
    prefix l2nm;
    reference
      "RFC 9291: A YANG Network Data Model for Layer 2 VPNs";
  }
  import ietf-ac-svc {
    prefix ac-svc;
    reference
      "RFC XXXX: YANG Service Data Models for Attachment Circuits";
  }

  organization
    "IETF OPSAWG (Operations and Management Area Working Group)";
  contact
    "WG Web:   <https://datatracker.ietf.org/wg/opsawg/>
     WG List:  <mailto:opsawg@ietf.org>

     Editor:   Mohamed Boucadair
               <mailto:mohamed.boucadair@orange.com>
     Author:   Richard Roberts
               <mailto:rroberts@juniper.net>
     Author:   Samier Barguil
               <mailto:ssamier.barguil_giraldo@nokia.com>
     Author:   Oscar Gonzalez de Dios
               <mailto:oscar.gonzalezdedios@telefonica.com>";
  description
    "This YANG module defines a YANG model for augmenting the LxSM
     and the LxNM with attachment circuit references.

     Copyright (c) 2023 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 2023-07-13 {
    description
      "Initial revision.";
    reference
      "RFC XXXX: A YANG Data Model for Augmenting VPN Service
                 and Network Models with Attachment Circuits";
  }

  grouping ac-glue {
    description
      "A set of AC-related data.";
    leaf-list ac-ref {
      type ac-svc:attachment-circuit-reference;
      description
        "A reference to the AC as exposed at the service that
         was provisionned using the AC module.";
    }
  }

  augment "/l2vpn-svc:l2vpn-svc"
        + "/l2vpn-svc:sites/l2vpn-svc:site"
        + "/l2vpn-svc:site-network-accesses"
        + "/l2vpn-svc:site-network-access" {
    description
      "Augments VPN network access with AC provisioning details.";

    uses ac-glue;
  }

  augment "/l3vpn-svc:l3vpn-svc"
        + "/l3vpn-svc:sites/l3vpn-svc:site"
        + "/l3vpn-svc:site-network-accesses"
        + "/l3vpn-svc:site-network-access" {
    description
      "Augments VPN network access with AC provisioning details.";

    uses ac-glue;
  }

  augment "/l2nm:l2vpn-ntw/l2nm:vpn-services/l2nm:vpn-service"
        + "/l2nm:vpn-nodes/l2nm:vpn-node"
        + "/l2nm:vpn-network-accesses/l2nm:vpn-network-access" {
    description
      "Augments VPN network access with AC provisioning details.";

    uses ac-glue;
  }

  augment "/l3nm:l3vpn-ntw/l3nm:vpn-services/l3nm:vpn-service"
        + "/l3nm:vpn-nodes/l3nm:vpn-node"
        + "/l3nm:vpn-network-accesses/l3nm:vpn-network-access" {
    description
      "Augments VPN network access with AC provisioning details.";

    uses ac-glue;
  }
}

<CODE ENDS>

6. Security Considerations

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

The Network Configuration Access Control Model (NACM) [RFC8341] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content.

There are a number of data nodes defined in this YANG module that are writable/creatable/deletable (i.e., config true, which is the default). These data nodes may be considered sensitive or vulnerable in some network environments. Write operations (e.g., edit-config) and delete operations to these data nodes without proper protection or authentication can have a negative effect on network operations. These are the subtrees and data nodes and their sensitivity/ vulnerability in the "ietf-ac-svc" module:

Some of the readable data nodes in this YANG module may be considered sensitive or vulnerable in some network environments. It is thus important to control read access (e.g., via get, get-config, or notification) to these data nodes. These are the subtrees and data nodes and their sensitivity/vulnerability in the "ietf-ac-svc" module:

7. IANA Considerations

IANA is requested to register the following URI in the "ns" subregistry within the "IETF XML Registry" [RFC3688]:

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

IANA is requested to register the following YANG module in the "YANG Module Names" registry [RFC6020] within the "YANG Parameters" registry group.

   Name:  ietf-ac-glue
   Namespace:  urn:ietf:params:xml:ns:yang:ietf-ac-glue
   Prefix:  ac-glue
   Maintained by IANA?  N
   Reference:  RFC xxxx

8. References

8.1. Normative References

[I-D.boro-opsawg-teas-attachment-circuit]
Boucadair, M., Roberts, R., de Dios, O. G., Barguil, S., and B. Wu, "YANG Data Models for 'Attachment Circuits'-as-a-Service (ACaaS)", Work in Progress, Internet-Draft, draft-boro-opsawg-teas-attachment-circuit-07, , <https://datatracker.ietf.org/doc/html/draft-boro-opsawg-teas-attachment-circuit-07>.
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/rfc/rfc2119>.
[RFC3688]
Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, , <https://www.rfc-editor.org/rfc/rfc3688>.
[RFC4364]
Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, , <https://www.rfc-editor.org/rfc/rfc4364>.
[RFC6020]
Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, , <https://www.rfc-editor.org/rfc/rfc6020>.
[RFC6241]
Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, , <https://www.rfc-editor.org/rfc/rfc6241>.
[RFC6242]
Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, , <https://www.rfc-editor.org/rfc/rfc6242>.
[RFC8040]
Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, , <https://www.rfc-editor.org/rfc/rfc8040>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC8299]
Wu, Q., Ed., Litkowski, S., Tomotaki, L., and K. Ogaki, "YANG Data Model for L3VPN Service Delivery", RFC 8299, DOI 10.17487/RFC8299, , <https://www.rfc-editor.org/rfc/rfc8299>.
[RFC8341]
Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, , <https://www.rfc-editor.org/rfc/rfc8341>.
[RFC8446]
Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, , <https://www.rfc-editor.org/rfc/rfc8446>.
[RFC8466]
Wen, B., Fioccola, G., Ed., Xie, C., and L. Jalil, "A YANG Data Model for Layer 2 Virtual Private Network (L2VPN) Service Delivery", RFC 8466, DOI 10.17487/RFC8466, , <https://www.rfc-editor.org/rfc/rfc8466>.
[RFC9182]
Barguil, S., Gonzalez de Dios, O., Ed., Boucadair, M., Ed., Munoz, L., and A. Aguado, "A YANG Network Data Model for Layer 3 VPNs", RFC 9182, DOI 10.17487/RFC9182, , <https://www.rfc-editor.org/rfc/rfc9182>.
[RFC9291]
Boucadair, M., Ed., Gonzalez de Dios, O., Ed., Barguil, S., and L. Munoz, "A YANG Network Data Model for Layer 2 VPNs", RFC 9291, DOI 10.17487/RFC9291, , <https://www.rfc-editor.org/rfc/rfc9291>.

8.2. Informative References

[RFC7665]
Halpern, J., Ed. and C. Pignataro, Ed., "Service Function Chaining (SFC) Architecture", RFC 7665, DOI 10.17487/RFC7665, , <https://www.rfc-editor.org/rfc/rfc7665>.
[RFC8340]
Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", BCP 215, RFC 8340, DOI 10.17487/RFC8340, , <https://www.rfc-editor.org/rfc/rfc8340>.

Appendix A. Examples

Add some examples.

Acknowledgments

Thanks to TBC for the comments.

Authors' Addresses

Mohamed Boucadair (editor)
Orange
Richard Roberts
Juniper
Samier Barguil Giraldo
Nokia
Oscar Gonzalez de Dios
Telefonica