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TEAS Working Group                                      Fabio Peruzzini
Internet Draft                                                      TIM
Intended status: Informational                               Italo Busi
                                                                 Huawei
                                                            Daniel King
                                                     Old Dog Consulting
                                                         Sergio Belotti
                                                                  Nokia
                                                    Gabriele Galimberti
                                                                  Cisco

Expires: January 2020                                     July 22, 2019



      Applicability of Abstraction and Control of Traffic Engineered
            Networks (ACTN) to Packet Optical Integration (POI)


               draft-peru-teas-actn-poi-applicability-01.txt


Status of this Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on January 22, 2020.







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Copyright Notice

   Copyright (c) 2019 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
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   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

   This document considers the applicability of ACTN to Packet Optical
   Integration (POI) and IP and Optical DWDM domain internetworking,
   and specifically the YANG models being defined by the IETF to
   support this deployment architecture.

   In this document we highlight the IETF protocols and data models
   that may be used for the ACTN and control of POI networks, with
   particular focus on the interfaces between the MDSC (Multi-Domain
   Service Coordinator) and the underlying Packet and Optical Domain
   Controllers (P-PNC and O-PNC) to support Packet Optical Integration
   (POI) use cases.

Table of Contents


   1. Introduction...................................................3
   2. Reference Scenario.............................................3
      2.1. Generic Assumptions.......................................5
   3. Scenario 1 - Topology discovery, network inventory and multilayer
   correlation.......................................................5
      3.1. Common YANG models used at the MPIs.......................6
         3.1.1. YANG models used at the Optical MPIs.................6
         3.1.2. Required YANG models at the Packet MPIs..............7
      3.2. Inter-domain link Discovery...............................7
   4. Scenario 2 - Provisioning of an IP Link over DWDM..............8
      4.1. YANG models used at the MPIs..............................8
         4.1.1. YANG models used at the Optical MPIs.................8
         4.1.2. Required YANG models at the Packet MPIs..............9
      4.2. IP Link Setup Procedure...................................9



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   5. Security Considerations.......................................10
   6. Operational Considerations....................................10
   7. IANA Considerations...........................................10
   8. References....................................................10
      8.1. Normative References.....................................10
      8.2. Informative References...................................12
   9. Acknowledgments...............................................12
   10. Authors' Addresses...........................................12

1. Introduction

   This document aims to collect information about the level of
   protocols and data models standardization implementations of ACTN
   architecture, with particular focus on the interfaces between the
   MDSC (Multi-Domain Service Coordinator) and underlying Packet and
   Optical Domain Controllers (P-PNC and O-PNC), for Packet Optical
   Integration (POI).

   Understanding the level of standardization and the gaps will help to
   better assess the feasibility of integration between IP and Optical
   DWDM domain, in an end-to-end multi-vendor service provisioning
   perspective.

   In this document, key use cases will be described, and for each use
   case according to the ACTN architecture shown in Figure 1, the scope
   will address the interactions with both the IP and optical domains.

   For both domains, information on functions, protocols and data
   models, available on each use case, must be reported.

2. Reference Scenario

   This document is considering a network scenario with multiple
   Optical domains and multiple Packet domains.

   Figure 1 shows this scenario in case of two Optical domains and two
   Packet domains:












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                              +----------+
                              |   MDSC   |
                              +-----+----+
                                    |
                  +-----------+-----+------+-----------+
                  |           |            |           |
             +----+----+ +----+----+  +----+----+ +----+----+
             | P-PNC 1 | | O-PNC 1 |  | O-PNC 2 | | P-PNC 2 |
             +----+----+ +----+----+  +----+----+ +----+----+
                  |           |            |           |
                  |           \            /           |
        +-------------------+  \          /  +-------------------+
   CE  / PE             ASBR \  |        /  / ASBR            PE  \  CE
   o--/---o               o---\-|-------|--/---o               o---\--o
      \   :               :   / |       |  \   :               :   /
       \  :  AS Domain 1  :  /  |       |   \  :  AS Domain 2  :  /
        +-:---------------:-+   |       |    +-:---------------:--+
          :               :     |       |      :               :
          :               :     |       |      :               :
        +-:---------------:------+     +-------:---------------:--+
       /  :               :       \   /        :               :   \
      /   o...............o        \ /         o...............o    \
      \     Optical Domain 1       / \       Optical Domain 2       /
       \                          /   \                            /
        +------------------------+     +--------------------------+

                       Figure 1 - Reference Scenario

   The ACTN architecture, defined in [RFC8453], is used to control this
   multi-domain network where each P-PNC is responsible for controlling
   its IP domain (AS), and each O-PNC is responsible for controlling
   its Optical Domain. The MDSC is responsible for coordinating the
   whole multi-domain multi-layer (Packet and Optical) network. A
   specific standard interface (MPI) permits MDSC to interact with the
   different Provisioning Network Controller (O/P-PNCs). The MPI
   interface presents an abstracted topology to MDSC hiding technology-
   specific aspects of the network and hiding topology details
   depending on the policy chosen regarding the level of abstraction
   supported. The level of abstraction can be obtained based on P-PNC
   and O-PNC configuration parameters (e.g. provide the potential
   connectivity between any PE and any ABSR in an MPLS-TE network).

   In this scenario it is assumed that:





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   o  The domain boundaries between the IP and Optical domains are
      congruent. In other words, one Optical domain supports
      connectivity between Routers in one and only one Packet Domain.

   o  Inter-domain links exist only between Packet domains (i.e.,
      between ASBR routers) and between Packet and Optical domains
      (i.e., between routers and ROADMs). In other words, there are no
      inter-domain links between Optical domains

   o  The interfaces between the routers and the ROADM's are "Ethernet"
      physical interfaces

   o  The interfaces between the ASBR routers are "Ethernet" physical
      interfaces

2.1. Generic Assumptions

   This section describes general assumptions which are applicable at
   all the MPI interfaces, between each PNC (Optical or Packet) and the
   MDSC, and also to all the scenarios discussed in this document.

   The data models used on these interfaces are assumed to use the YANG
   1.1 Data Modeling Language, as defined in [RFC7950].

   The RESTCONF protocol, as defined in [RFC8040], using the JSON
   representation, defined in [RFC7951], is assumed to be used at these
   interfaces.

   As required in [RFC8040], the "ietf-yang-library" YANG module
   defined in [RFC8525] is used to allow the MDSC to discover the set
   of YANG modules supported by each PNC at its MPI.

3. Scenario 1 - Topology discovery, network inventory and multilayer
   correlation

   In this scenario, the MSDC needs to discover the network topology,
   at both WDM and IP layers, in terms of nodes (NEs) and links,
   including inter-domain links.

   Each PNC provides to the MDSC an abstract topology view of the WDM
   or of the IP topology of the domain it controls. This topology is
   abstract in the sense that some detailed NE information is hidden at
   the MPI, but all the NEs and physical links are exposed as abstract
   nodes and links within the abstract topology.





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   The MDSC also keeps an up-to-date network inventory of both IP and
   WDM layers and correlates such information (e.g., which port,
   lambda, and the direction being used by a specific IP service on the
   WDM equipment).

3.1. Common YANG models used at the MPIs

   Both Optical and Packet PNCs use the following common topology YANG
   models at the MPI to report their abstract topologies:

   o  The Base Network Model, defined in the "ietf-network" YANG module
      of [RFC8345]

   o  The Base Network Topology Model, defined in the "ietf-network-
      topology" YANG module of [RFC8345], which augments the Base
      Network Model

   o  The TE Topology Model, defined in the "ietf-te-topology" YANG
      module of [TE-TOPO], which augments the Base Network Topology
      Model

   These common YANG models are generic and augmented by technology-
   specific YANG modules as described in the following sections.

3.1.1. YANG models used at the Optical MPIs

   The Optical PNC also uses at least the following technology-specific
   topology YANG models, providing WDM and Ethernet technology-specific
   augmentations of the generic TE Topology Model:

   o  The WSON Topology Model, defined in the "ietf-wson-topology" YANG
      modules of [WSON-TOPO], or the Flexi-grid Topology Model, defined
      in the "ietf-flexi-grid-topology" YANG module of [Flexi-TOPO].

   o  The Ethernet Topology Model, defined in the "ietf-eth-te-
      topology" YANG module of [CLIENT-TOPO]

   The WSON Topology Model or, alternatively, the Flexi-grid Topology
   model is used to report the DWDM network topology (e.g., ROADMs and
   links) depending on whether the DWDM optical network is based on
   fixed grid or flexible-grid.

   The Ethernet Topology is used to report the access links between the
   IP routers and the edge ROADMs.





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3.1.2. Required YANG models at the Packet MPIs

   The Packet PNC also uses at least the following technology-specific
   topology YANG models, providing IP and Ethernet technology-specific
   augmentations of the generic Topology Models:

   o  The L3 Topology Model, defined in the "ietf-l3-unicast-topology"
      YANG modules of [RFC8346], which augments the Base Network
      Topology Model

   o  The Ethernet Topology Model, defined in the "ietf-eth-te-
      topology" YANG module of [CLIENT-TOPO], which augments the TE
      Topology Model

   The Ethernet Topology Model is used to report the access links
   between the IP routers and the edge ROADMs as well as the
   inter-domain links between ASBRs, while the L3 Topology Model is
   used to report the IP network topology (e.g., IP routers and links).

3.2. Inter-domain link Discovery

   In the reference network of Figure 1, there are two types of
   inter-domain links:

   o  Links between two IP domains (ASes)

   o  Links between an IP router and a ROADM

   Both types of links are Ethernet physical links.

   The inter-domain link information is reported to the MDSC by the two
   adjacent PNCs, controlling the two ends of the inter-domain link.

   The MDSC can understand how to merge these inter-domain links
   together using the plug-id attribute defined in the TE Topology
   Model [TE-TOPO], as described in as described in section 4.3 of [TE-
   TOPO].

   A more detailed description of how the plug-id can be used to
   discover inter-domain link is also provided in section 5.1.4 of
   [TNBI].

   Both types of inter-domain links are discovered using the plug-id
   attributes reported in the Ethernet Topologies exposed by the two
   adjacent PNCs. The MDSC can also discover an inter-domain IP
   link/adjacency between the two IP LTPs, reported in the IP



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   Topologies exposed by the two adjacent P-PNCs, supported by the two
   ETH LTPs of an Ethernet Link discovered between these two P-PNCs.

   Two options are possible to discover these inter-domain links:

   1. Static configuration

   2. LLDP [IEEE 802.1AB] automatic discovery

   Since the static configuration requires an administrative burden to
   configure network-wide unique identifiers, the automatic discovery
   solution based on LLDP is preferable when LLDP is supported.

   As outlined in [TNBI], the encoding of the plug-id namespace as well
   as of the LLDP information within the plug-id value is
   implementation specific and needs to be consistent across all the
   PNCs.

4. Scenario 2 - Provisioning of an IP Link over DWDM

   In this scenario, the MSDC needs to coordinate the creation of an IP
   link, or a LAG, between two routers through a DWDM network.

   It is assumed that the MDSC has already discovered the whole network
   topology as described in section 3.

4.1. YANG models used at the MPIs

4.1.1. YANG models used at the Optical MPIs

   The Optical PNC uses at least the following YANG models:

   o  The TE Tunnel Model, defined in the "ietf-te" YANG module of
      [TE-TUNNEL]

   o  The WSON Tunnel Model, defined in the "ietf-wson-tunnel" YANG
      modules of [WSON-TUNNEL], or the Flexi-grid Media Channel Model,
      defined in the "ietf-flexi-grid-media-channel" YANG module of
      [Flexi-MC]

   o  The Ethernet Client Signal Model, defined in the "ietf-eth-tran-
      service" YANG module of [CLIENT-SIGNAL]

   The TE Tunnel model is generic and augmented by technology-specific
   models such as the WSON Tunnel Model and the Flexi-grid Media
   Channel Model.



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   The WSON Tunnel Model or, alternatively, the Flexi-grid Media
   Channel Model are used to setup connectivity within the DWDM network
   depending on whether the DWDM optical network is based on fixed grid
   or flexible-grid.

   The Ethernet Client Signal Model is used to configure the steering
   of the Ethernet client traffic between Ethernet access links and TE
   Tunnels, which in this case could be either WSON Tunnels or
   Flexi-Grid Media Channels. This model is generic and applies to any
   technology-specific TE Tunnel: technology-specific attributes are
   provided by the technology-specific models which augment the generic
   TE-Tunnel Model.

4.1.2. Required YANG models at the Packet MPIs

   The Packet PNC uses at least the following topology YANG models:

   o  The Base Network Model, defined in the "ietf-network" YANG module
      of [RFC8345] (see section 3.1)

   o  The Base Network Topology Model, defined in the "ietf-network-
      topology" YANG module of [RFC8345] (see section 3.1)

   o  The L3 Topology Model, defined in the "ietf-l3-unicast-topology"
      YANG modules of [RFC8346] (see section 3.1.1)

   If, as discussed in section 4.2, IP Links created over DWDM can be
   automatically discovered by the P-PNC, the IP Topology is needed
   only to report these IP Links after being discovered by the P-PNC.

   The IP Topology can also be used to configure the IP Links created
   over DWDM.

4.2. IP Link Setup Procedure

   The MDSC requires the O-PNC to setup a WDM Tunnel (either a WSON
   Tunnel or a Flexi-grid Tunnel) within the DWDM network between the
   two Optical Transponders (OTs) associated with the two access links.

   The Optical Transponders are reported by the O-PNC as Trail
   Termination Points (TTPs), defined in [TE-TOPO], within the WDM
   Topology. The association between the Ethernet access link and the
   WDM TTP is reported by the Inter-Layer Lock (ILL) identifiers,
   defined in [TE-TOPO], reported by the O-PNC within the Ethernet
   Topology and WDM Topology.




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   The MDSC also requires the O-PNC to steer the Ethernet client
   traffic between the two access Ethernet Links over the WDM Tunnel.

   After the WDM Tunnel has been setup and the client traffic steering
   configured, the two IP routers can exchange Ethernet packets between
   themselves, including LLDP messages.

   If LLDP [IEEE 802.1AB] is used between the two routers, the P-PNC
   can automatically discover the IP Link being setup by the MDSC. The
   IP LTPs terminating this IP Link are supported by the ETH LTPs
   terminating the two access links.

   Otherwise, the MDSC needs to require the P-PNC to configure an IP
   Link between the two routers: the MDSC also configures the two ETH
   LTPs which support the two IP LTPs terminating this IP Link.

5. Security Considerations

   Several security considerations have been identified and will be
   discussed in future versions of this document.

6. Operational Considerations

   Telemetry data, such as the collection of lower-layer networking
   health and consideration of network and service performance from POI
   domain controllers, may be required. These requirements and
   capabilities will be discussed in future versions of this document.

7. IANA Considerations

   This document requires no IANA actions.

8. References

8.1. Normative References

   [RFC7950] Bjorklund, M. et al., "The YANG 1.1 Data Modeling
             Language", RFC 7950, August 2016.

   [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", RFC
             7951, August 2016.

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





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   [RFC8345] Clemm, A., Medved, J. et al., "A Yang Data Model for
             Network Topologies", RFC8345, March 2018.

   [RFC8346] Clemm, A. et al., "A YANG Data Model for Layer 3
             Topologies", RFC8346, March 2018.

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

   [RFC8525] Bierman, A. et al., "YANG Library", RFC 8525, March 2019.

   [IEEE 802.1AB] IEEE 802.1AB-2016, "IEEE Standard for Local and
             metropolitan area networks - Station and Media Access
             Control Connectivity Discovery", March 2016.

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

   [WSON-TOPO] Lee, Y. et al., " A YANG Data Model for WSON (Wavelength
             Switched Optical Networks)", draft-ietf-ccamp-wson-yang,
             work in progress.

   [Flexi-TOPO]   Lopez de Vergara, J. E. et al., "YANG data model for
             Flexi-Grid Optical Networks", draft-ietf-ccamp-flexigrid-
             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.

   [WSON-TUNNEL]  Lee, Y. et al., "A Yang Data Model for WSON Tunnel",
             draft-ietf-ccamp-wson-tunnel-model, work in progress.

   [Flexi-MC]  Lopez de Vergara, J. E. et al., "YANG data model for
             Flexi-Grid media-channels", draft-ietf-ccamp-flexigrid-
             media-channel-yang, work in progress.

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





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8.2. Informative References

   [TNBI]    Busi, I., Daniel, K. et al., "Transport Northbound
             Interface Applicability Statement", draft-ietf-ccamp-
             transport-nbi-app-statement, work in progress.

9. Acknowledgments

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

   Some of this analysis work was supported in part by the European
   Commission funded H2020-ICT-2016-2 METRO-HAUL project (G.A. 761727).

10. Authors' Addresses

   Fabio Peruzzini
   TIM

   Email: fabio.peruzzini@telecomitalia.it


   Italo Busi
   Huawei

   Email: Italo.busi@huawei.com



   Daniel King
   Old Dog Consulting

   Email: daniel@olddog.co.uk



   Sergio Belotti
   Nokia

   Email: sergio.belotti@nokia.com



   Gabriele Galimberti
   Cisco

   Email: ggalimbe@cisco.com



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   Zheng Yanlei
   China Unicom

   Email: zhengyanlei@chinaunicom.cn



   Washington Costa Pereira Correia
   TIM Brasil

   Email: wcorreia@timbrasil.com.br



   Jean-Francois Bouquier
   Vodafone

   Email: jeff.bouquier@vodafone.com





























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