Profiles for Traffic Engineering (TE) Topology Data Model
draft-busi-teas-te-topology-profiles-01

Versions: 00 01                                                         
TEAS Working Group                                           Italo Busi
Internet Draft                                                   Huawei
Intended status: Informational                               Xufeng Liu
                                                         Volta Networks
                                                           Igor Bryskin
                                                             Individual
                                                    Vishnu Pavan Beeram
                                                             Tarek Saad
                                                       Juniper Networks
                                                 Oscar Gonzalez de Dios
                                                             Telefonica

Expires: July 2021                                     January 11, 2021



         Profiles for Traffic Engineering (TE) Topology Data Model
                  draft-busi-teas-te-topology-profiles-00


Abstract

   This document describes how profiles of the Traffic Engineering (TE)
   Topology Model, defined in RFC8795, can be used to address
   applications beyond "Traffic Engineering".

Status of this Memo

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   This Internet-Draft will expire on July 11, 2021.

Copyright Notice

   Copyright (c) 2021 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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction...................................................2
   2. Examples of non-TE scenarios...................................3
      2.1. UNI Topology Discovery....................................3
      2.2. Administrative and Operational status management..........5
      2.3. Geolocation...............................................7
      2.4. Overlay and Underlay non-TE Topologies....................8
      2.5. Nodes with switching limitations.........................10
   3. Technology-specific augmentations.............................11
   4. Security Considerations.......................................13
   5. IANA Considerations...........................................13
   6. References....................................................14
      6.1. Normative References.....................................14
      6.2. Informative References...................................14
   Acknowledgments..................................................14
   Contributors.....................................................14
   Authors' Addresses...............................................15

1. Introduction

   There are many network scenarios being discussed in various IETF
   Working Groups (WGs) that are not classified as "Traffic Engineering"
   but can be addressed by a sub-set (profile) of the Traffic
   Engineering (TE) Topology YANG data model, defined in [RFC8795].

   Traffic Engineering (TE) is defined in [RFC3272bis] as aspects of
   Internet network engineering that deal with the issues of performance
   evaluation and performance optimization of operational IP networks.



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   TE encompasses the application of technology and scientific
   principles to the measurement, characterization, modeling, and
   control of Internet traffic.

   The TE Topology Model is augmenting the Network Topology Model
   defined in [RFC8345] with generic and technology-agnostic features
   that some are strictly applicable to TE networks, while others
   applicable to both TE and non-TE networks.

   Examples of such features that are applicable to both TE and non-TE
   networks are: inter-domain link discovery (plug-id), geo-
   localization, and admin/operational status.

   It is also worth noting that the TE Topology Model is quite an
   extensive and comprehensive model in which most features are
   optional. Therefore, even though the full model appears to be
   complex, at the first glance, a sub-set of the model (profile) can be
   used to address specific scenarios, e.g. suitable also to non-TE use
   cases.

   The implementation of such TE Topology profiles can simplify and
   expedite adoption of the full TE topology YANG data model, and allow
   for its reuse even for non-TE use case. The key question being
   whether all or some of the attributes defined in the TE Topology
   Model are needed to address a given network scenario.

   Section 2 provides examples where profiles of the TE Topology Model
   can be used to address some generic use cases applicable to both TE
   and non-TE technologies.

2. Examples of non-TE scenarios

2.1. UNI Topology Discovery

   UNI Topology Discovery is independent from whether the network is TE
   or non-TE.

   The TE Topology Model supports inter-domain link discovery (including
   but not being limited to UNI link discovery) using the plug-id
   attribute. This solution is quite generic and does not require the
   network to be a TE network.

   The following profile of the TE Topology model can be used for the
   UNI Topology Discovery:





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   module: ietf-te-topology

     augment /nw:networks/nw:network/nw:network-types:
       +--rw te-topology!

     augment /nw:networks/nw:network/nw:node/nt:termination-point:
       +--rw te-tp-id?   te-types:te-tp-id
       +--rw te!
          +--rw admin-status?
          |       te-types:te-admin-status
          +--rw inter-domain-plug-id?             binary
          +--ro oper-status?
                  te-types:te-oper-status

                          Figure 1 - UNI Topology

   The profile data model shown in Figure 1 can be used to discover TE
   and non TE UNIs as well as to discover UNIs for TE or non TE
   networks.

   Such a UNI TE Topology profile model can also be used with
   technology-specific UNI augmentations, as described in section 3.

   For example, in [CLIENT-TOPO], the eth-svc container is defined to
   represent the capabilities of the Termination Point (TP) to be
   configured as an Ethernet client UNI, together with the Ethernet
   classification and VLAN operations supported by that TP.

   The [OTN-TOPO] provides another example, where:

   o  the client-svc container is defined to represent the capabilities
      of the TP to be configured as an transparent client UNI (e.g.,
      STM-N, Fiber Channel or transparent Ethernet);

   o  the OTN technology-specific Link Termination Point (LTP)
      augmentations are defined to represent the capabilities of the TP
      to be configured as an OTN UNI, together with the information
      about OTN label and bandwidth availability at the OTN UNI.

   For example, the UNI TE Topology profile can be used to model
   features defined in [UNI-TOPO]:

   o  The inter-domain-plug-id attribute would provide the same
      information as the attachment-id attribute defined in [UNI-TOPO];





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   o  The admin-status and oper-status that exists in this TE topology
      profile can provide the same information as the admin-status and
      oper-status attributes defined in [UNI-TOPO].

   Following the same approach in [CLIENT-TOPO] and [OTN-TOPO], the type
   and encapsulation-type attributes can be defined by technology-
   specific UNI augmentations to represent the capability of a TP to be
   configured as a L2VPN/L3VPN UNI Service Attachment Point (SAP).

   The advantages of using a TE Topology customized profile would be
   having common solutions for:

   o  discovering UNIs as well as inter-domain NNI links, which is
      applicable to any technology (TE or non TE) used at the UNI or
      within the network;

   o  modelling non TE UNIs such as Ethernet, and TE UNIs such as OTN,
      as well as UNIs which can configured as TE or non-TE (e.g., being
      configured as either Ethernet or OTN UNI).

2.2. Administrative and Operational status management

   The TE Topology Model supports the management of administrative and
   operational state, including also the possibility to associate some
   administrative names, for nodes, termination points and links. This
   solution is generic and also does not require the network to be a TE
   network.

   The following profile of the TE Topology Model can be used for
   administrative and operational state management:



















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   module: ietf-te-topology

     augment /nw:networks/nw:network/nw:network-types:
       +--rw te-topology!

        augment /nw:networks/nw:network:
          +--rw te-topology-identifier
          |  +--rw provider-id?   te-global-id
          |  +--rw client-id?     te-global-id
          |  +--rw topology-id?   te-topology-id
          +--rw te!
             +--rw name?                     string

        augment /nw:networks/nw:network/nw:node:
          +--rw te-node-id?   te-types:te-node-id
          +--rw te!
             +--rw te-node-attributes
             |  +--rw admin-status?            te-types:te-admin-status
             |  +--rw name?                    string
             +--ro oper-status?                   te-types:te-oper-
   status

        augment /nw:networks/nw:network/nt:link:
          +--rw te!
             +--rw te-link-attributes
             |  +--rw name?                             string
             |  +--rw admin-status?
             |  |       te-types:te-admin-status
             +--ro oper-status?                   te-types:te-oper-
   status

        augment /nw:networks/nw:network/nw:node/nt:termination-point:
          +--rw te-tp-id?   te-types:te-tp-id
          +--rw te!
             +--rw admin-status?
             |       te-types:te-admin-status
             +--rw name?                             string
             +--ro oper-status?
                     te-types:te-oper-status

       Figure 2 - Generic Topology with admin and operational state

   The TE topology data model profile shown in Figure 2 is applicable to
   any technology (TE or non-TE) that requires management of the
   administrative and operational state and administrative names for
   nodes, termination points and links.



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2.3. Geolocation

   The TE Topology model supports the management of geolocation
   coordinates for nodes and termination points. This solution is
   generic and does not necessarily require the network to be a TE
   network.

   The TE topology data model profile shown in Figure 3can be used to
   model geolocation data for networks.

   module: ietf-te-topology

     augment /nw:networks/nw:network/nw:network-types:
       +--rw te-topology!

        augment /nw:networks/nw:network:
          +--rw te-topology-identifier
          |  +--rw provider-id?   te-global-id
          |  +--rw client-id?     te-global-id
          |  +--rw topology-id?   te-topology-id
          +--rw te!
             +--ro geolocation
                +--ro altitude?    int64
                +--ro latitude?    geographic-coordinate-degree
                +--ro longitude?   geographic-coordinate-degree

        augment /nw:networks/nw:network/nw:node:
          +--rw te-node-id?   te-types:te-node-id
          +--rw te!
             +--ro geolocation
             |  +--ro altitude?    int64
             |  +--ro latitude?    geographic-coordinate-degree
             |  +--ro longitude?   geographic-coordinate-degree

        augment /nw:networks/nw:network/nw:node/nt:termination-point:
          +--rw te-tp-id?   te-types:te-tp-id
          +--rw te!
             +--ro geolocation
                +--ro altitude?    int64
                +--ro latitude?    geographic-coordinate-degree
                +--ro longitude?   geographic-coordinate-degree

         Figure 3 - Generic Topology with geolocation information






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   This profile is applicable to any network technology (TE or non-TE)
   that requires management of the geolocation information for its nodes
   and termination points.

2.4. Overlay and Underlay non-TE Topologies

   The TE Topology model supports the management of overlay/underlay
   relationship for nodes and links, as described in section 5.8 of
   [RFC8795]. This solution is generic and does not require the network
   to be a TE network.

   The following TE topology data model profile can be used to manage
   overlay/underlay network data:




































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   module: ietf-te-topology

     augment /nw:networks/nw:network/nw:network-types:
       +--rw te-topology!

        augment /nw:networks/nw:network/nw:node:
          +--rw te-node-id?   te-types:te-node-id
          +--rw te!
             +--rw te-node-attributes
             |  +--rw underlay-topology {te-topology-hierarchy}?
             |     +--rw network-ref?   -> /nw:networks/network/network-
   id

        augment /nw:networks/nw:network/nt:link:
          +--rw te!
             +--rw te-link-attributes
             |  +--rw underlay {te-topology-hierarchy}?
             |  |  +--rw enabled?                     boolean
             |  |  +--rw primary-path
             |  |  |  +--rw network-ref?
             |  |  |  |       -> /nw:networks/network/network-id
             |  |  |  +--rw path-element* [path-element-id]
             |  |  |     +--rw path-element-id              uint32
             |  |  |     +--rw (type)?
             |  |  |        +--:(numbered-link-hop)
             |  |  |        |  +--rw numbered-link-hop
             |  |  |        |     +--rw link-tp-id    te-tp-id
             |  |  |        |     +--rw hop-type?     te-hop-type
             |  |  |        |     +--rw direction?    te-link-direction
             |  |  |        +--:(unnumbered-link-hop)
             |  |  |        |  +--rw unnumbered-link-hop
             |  |  |        |     +--rw link-tp-id    te-tp-id
             |  |  |        |     +--rw node-id       te-node-id
             |  |  |        |     +--rw hop-type?     te-hop-type
             |  |  |        |     +--rw direction?    te-link-direction

       Figure 4 - Generic Topology with overlay/underlay information

   This profile is applicable to any technology (TE or non-TE) when it
   is needed to manage the overlay/underlay information. It is also
   allows a TE underlay network to support a non-TE overlay network and,
   vice versa, a non-TE underlay network to support a TE overlay
   network.






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2.5. Nodes with switching limitations

   A node can have some switching limitations where connectivity is not
   possible between all its TP pairs, for example when:

   o  the node represents a physical device with switching limitations;

   o  the node represents an abstraction of a network topology.

   This scenario is generic and applies to both TE and non-TE
   technologies.

   A connectivity TE Topology profile data model supports the management
   of the node connectivity matrix to represent feasible connections
   between termination points across the nodes. This solution is generic
   and does not necessarily require a TE enabled network.

   The following profile of the TE Topology model can be used for nodes
   with connectivity constraints:

   module: ietf-te-topology

     augment /nw:networks/nw:network/nw:network-types:
       +--rw te-topology!

        augment /nw:networks/nw:network/nw:node:
          +--rw te-node-id?   te-types:te-node-id
          +--rw te!
             +--rw te-node-attributes
             |  +--rw connectivity-matrices
             |  |  +--rw number-of-entries?     uint16
             |  |  +--rw is-allowed?            boolean
             |  |  +--rw connectivity-matrix* [id]
             |  |     +--rw id                  uint32
             |  |     +--rw from
             |  |     |  +--rw tp-ref?               leafref
             |  |     +--rw to
             |  |     |  +--rw tp-ref?               leafref
             |  |     +--rw is-allowed?         boolean

         Figure 5 - Generic Topology with connectivity constraints

   The TE topology data model profile shown in Figure 5 is applicable to
   any technology (TE or non-TE) networks that requires managing nodes
   with certain connectivity constraints. When used with TE




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   technologies, additional TE attributes, as defined in [RFC8795], can
   also be provided.

3. Technology-specific augmentations

   There are two main options to define technology-specific Topology
   Models which can use the attributes defined in the TE Topology Model
   [RFC8795].

   Both options are applicable to any possible profile such as those
   defined in section 2.

   The first option is to define a technology-specific TE Topology Model
   which augments the TE Topology Model, as shown in Figure 6:

                           +-------------------+
                           | Network Topology  |
                           +-------------------+
                                     ^
                                     |
                                     | Augments
                                     |
                         +-----------+-----------+
                         |      TE Topology      |
                         +-----------------------+
                                     ^
                                     |
                                     | Augments
                                     |
                          +----------+----------+
                          | Technology-Specific |
                          |     TE Topology     |
                          +---------------------+

                 Figure 6 Augmenting the TE Topology Model

   This approach is more suitable for cases when the technology-specific
   TE topology model provides augmentations to the TE Topology
   constructs, such as bandwidth information (e.g., link bandwidth),
   tunnel termination points (TTPs) or connectivity matrices.

   This is the approach currently used in [CLIENT TOPO] and [OTN TOPO].

   It is worth noting that a profile of the technology-specific TE
   Topology model not using any TE topology attribute or constructs can
   be used to address any use case that do not require these attributes.



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   The second option is to define a technology-specific Topology Model
   which augments the Network Topology Model and to rely on the multiple
   inheritance capability that is defined in [RFC8345] to allow using
   also the attributes defined in the TE Topology model:

                    +-----------------------+
                    |    Network Topology   |
                    +-----------------------+
                        ^               ^
                        |               |
           Augments +---+               +--+ Augments
                    |                      |
          +---------+---+       +----------+----------+
          | TE Topology |       | Technology-specific |
          |             |       |       Topology      |
          +-------------+       +---------------------+

   Figure 7 Augmenting the Network Topology Model with multi-inheritance

   This approach is more suitable in cases where the technology-specific
   Topology Model provides augmentation only to the constructs defined
   in the Network Topology Model, such as nodes, links, and termination
   points (TPs). Therefore, with this approach, only the generic
   attributes defined in the TE Topology Model could be used.

   It is also worth noting that in this case, technology-specific
   augmentations for the bandwidth information could not be defined.

   In principle, a third option, to define both a technology specific TE
   Topology Model which augments the TE Topology Model, and a
   technology-specific Topology Model which augments the Network
   Topology Model and to rely on the multiple inheritance capability, as
   shown in Figure 8, is possible:
















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                    +-----------------------+
                    |    Network Topology   |
                    +-----------------------+
                        ^               ^
                        |               |
           Augments +---+               +--+ Augments
                    |                      |
          +---------+---+       +----------+----------+
          | TE Topology |       | Technology-specific |
          |             |       |       Topology      |
          +-------------+       +---------------------+
                 ^
                 |
                 | Augments
                 |
      +----------+----------+
      | Technology-Specific |
      |     TE Topology     |
      +---------------------+

        Figure 8 Augmenting both the Network and TE Topology Models

   This option does not provide any technical advantage with respect to
   the first option, shown in Figure 6, but could be useful to add
   augmentations to the TE Topology constructs and re-using an already
   existing technology-specific Topology Model.

4. Security Considerations

   This document provides only information about how the TE Topology
   Model, as defined in [RFC8795], can be profiled to address some
   scenarios which are not considered as TE.

   As such, this document does not introduce any additional security
   considerations besides those already defined in [RFC8795].

5. IANA Considerations

   This document requires no IANA actions.










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6. References

6.1. Normative References

   [RFC8345] Clemm, A., Medved, J., Varga, R., Bahadur, N.,
             Ananthakrishnan, H., and X. Liu, "A YANG Data Model for
             Network Topologies", RFC 8345, DOI 10.17487/RFC8345, March
             2018, <https://www.rfc-editor.org/info/rfc8345>.

   [RFC8795] Liu, X., Bryskin, I., Beeram, V., Saad, T., Shah, H., and
             O. Gonzalez de Dios, "YANG Data Model for Traffic
             Engineering (TE) Topologies", RFC 8795, DOI
             10.17487/RFC8795, August 2020, <https://www.rfc-
             editor.org/info/rfc8795>.

6.2. Informative References

   [RFC3272bis]   Farrel A., "Overview and Principles of Internet
             Traffic Engineering", draft-dt-teas-rfc3272bis-00, work in
             progress.

   [UNI-TOPO]  Gonzalez de Dios, O. et al., "A YANG Model for User-
             Network Interface (UNI) Topologies", draft-ogondio-opsawg-
             uni-topology-01, work in progress.

   [CLIENT-TOPO]  Zheng, H. et al., "A YANG Data Model for Client-layer
             Topology", draft-zheng-ccamp-client-topo-yang-09, work in
             progress.

   [OTN-TOPO]  Zheng, H. et al., "A YANG Data Model for Optical
             Transport Network Topology", draft-ietf-ccamp-otn-topo-
             yang-11, work in progress.

Acknowledgments

   This document was prepared using 2-Word-v2.0.template.dot.

Contributors

   Aihua Guo
   Futurewei Inc.

   Email: aihuaguo.ietf@gmail.com






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   Haomian Zheng
   Huawei

   Email: zhenghaomian@huawei.com


   Sergio Belotti
   Nokia

   Email: sergio.belotti@nokia.com

Authors' Addresses

   Italo Busi
   Huawei

   Email: italo.busi@huawei.com


   Xufeng Liu
   Volta Networks

   Email: xufeng.liu.ietf@gmail.com


   Igor Bryskin
   Individual

   Email: i_bryskin@yahoo.com


   Vishnu Pavan Beeram
   Juniper Networks

   Email: vbeeram@juniper.net


   Tarek Saad
   Juniper Networks

   Email: tsaad@juniper.net








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   Oscar Gonzalez de Dios
   Telefonica

   Email: oscar.gonzalezdedios@telefonica.com













































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