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Network Working Group                                    Kwang-koog Lee
Internet Draft                                               Hosong Lee
Intended status: Informational                                       KT
Expires April 2014                                        Ricard Vilata
                                                                   CTTC
                                                           Victor Lopez
                                                             Telefonica


                                                      November 10, 2014

      ACTN Use-case for On-demand E2E Connectivity Services in Multiple
                      Vendor Domain Transport Networks


         draft-klee-actn-connectivity-multi-vendor-domains-02.txt


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   carefully, as they describe your rights and restrictions with
   respect to this document.

Abstract

   This document provides a use-case that addresses the need for
   facilitating the application of virtual network abstractions and the
   control and management of on-demand end-to-end provisioning of
   connections that traverse multiple vendor domain transport networks.

   These abstractions shall help create a virtualized environment
   supporting operators in viewing and controlling different vendor
   domains, especially for on-demand network connectivity service for a
   single operator.



Table of Contents

    1. Introduction..................................................2
   2. On-demand End-to-end Connectivity in Multi-vendor Domain
   Transport Networks................................................3
   3. Requirements...................................................5
   4. References.....................................................8
   5. Contributors...................................................8
   Intellectual Property Statement...................................9
   Disclaimer of Validity............................................9

1. Introduction

   Network operators build and operate their network using multiple
   domains in different dimensions. Domains may be defined by a
   collection of links and nodes (each of a different technology),
   administrative zones under the concern of a particular business
   entity, or vendor-specific "islands" where specific control
   mechanisms have to be applied. Due to the technology of each vendor,
   the optical components cannot be interconnected. Therefore each
   optical domain becomes an isolated island in terms of provisioning.
   The network operators use vendor-specific NMS implementations along
   with an operator-tailored umbrella provisioning system, which may
   include a technology specific Operations Support System (OSS).
   Thanks to the evolution of vendor specific SDN controllers, the
   network operators require a network entity, which abstract the
   details of the optical layer while enabling end-to-end provisioning
   of services. The establishment of end-to-end connections spanning
   several of these domains is a perpetual problem for operators, which
   need to address both interoperability and operational concerns at
   the control and data planes.


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   The introduction of new services, often requiring connections that
   traverse multiple domains, needs significant planning, and several
   manual operations to interface multiple vendor-specific domains in
   which specific control/management mechanisms of the vendor equipment
   have to be applied (e.g., EMS/NMS, OSS/BSS, control plane, SDN
   controller, etc.). Undoubtedly, establishing an on-demand end-to-end
   connection which requires provisioning based on dynamic resource
   information is more difficult in the current network context.

   This document provides a use-case that addresses the need for
   creating a virtualized environment supporting operators in viewing
   and controlling different vendor domains, especially for on-demand
   network connectivity service for a single operator. This will
   accelerate rapid service deployment of new services, including more
   dynamic and elastic services, and improve overall network operations
   and scaling of existing services.

   This use-case is a part of the overarching work, called Abstraction
   and Control of Transport Networks (ACTN). Related documents are the
   ACTN-framework [ACTN-Frame] and the problem statement [ACTN-PS].

2. On-demand End-to-end Connectivity in Multi-vendor Domain Transport
   Networks

   This section provides an architecture example to illustrate the
   context of the current challenges and issues operators face in
   delivering on-demand end-to-end connectivity services in operators'
   multi-vendor domain transport networks.

                                                                   |
     | /                    End-to-End Connection                \ |
     |/-----------------------------------------------------------\|
     |\-----------------------------------------------------------/|
     | \                                                         / |
     |                                                             |
     |                      +----------------+                     |
     |                      |                |                     |
     |                      |    Converged   |                     |
     |                      |  Packet-Optical|                     |
     |     +-------------+  |    Core Domain |  +-------------+    |
     |     |             |--|   (Vendor A)   |--|             |    |
   +----+  |    Access   |  +----------------+  |    Access   |  +----+
   | CE1|--|   Domain 1  |     |          |     |   Domain 3  |--| CE2|
   +----+  |  (Vendor B) |-----            -----|  (Vendor C) |  +----+
           +-------------+                      +-------------+


                      Figure 1. Multi-vendor Domains


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   As an illustrative example, consider a multi-domain transport
   network consisting of three domains: one core converged packet-
   optical domain (Vendor A) and two access domains (Vendors B and C).
   Each access domain is managed by its domain control/management
   mechanism which is often a proprietary vendor-specific scheme. The
   core domain is also managed by Vendor A's proprietary
   control/management mechanism (e.g., EMS/NMS, OSS/BSS, Control Plane,
   SDN Controller, or any combination of these entities, etc.) that may
   not interoperate with access domain control/management mechanisms or
   at best partially interoperate if Vendor A is same as Vendor B or
   Vendor C.

   Due to these domain boundaries, facilitating on-demand end-to-end
   connections (e.g., Ethernet Virtual Connections, etc.) that traverse
   multi-domains is not readily achieved. These domain controls are
   optimized for its local operation and in most cases not suited for
   controlling the end-to-end connectivity services. For instance, the
   discovery of the edge nodes that belong to other domains is hard to
   achieve partly because of the lack of the common API and its
   information model and control mechanisms thereof to disseminate the
   relevant information.

   Moreover, the path computation for any on-demand end-to-end
   connection would need abstraction of dynamic network resources and
   ways to find an optimal path that meets the connection's service
   requirements. This would require knowledge of both the domain level
   dynamic network resource information and the inter-domain
   connectivity information including domain gateway/peering points and
   the local domain policy.

   From an on-demand connection provisioning perspective, in order to
   facilitate a fast and reliable end-to-end signaling, each domain
   operation and management elements should ideally speak the same
   control protocols to its neighboring domains. However, this is not
   possible for the current network context unless a folk-lift green
   field technology deployment with a single vendor solution would be
   done. Although each domain applies the same protocol for the data
   plane, an end-to-end connectivity traversing multiple domains might
   not be provided due to a management and control mechanism focusing
   only on its own domain.

   From a network connectivity management perspective, it would require
   a mechanism to disseminate any connectivity issues from the local
   domain to the other domains whenever the local domain cannot resolve
   a connectivity issues. This is hard to achieve due to the lack of
   the common API and its agreed-upon information model and control
   mechanisms thereof to disseminate the relevant information.



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   From an operation's perspective, the current network environments
   are not conducive to offering on-demand end-to-end connectivity
   services in multi-vendor domain transport networks. For instance,
   when the performance monitoring inquiry is requested, operators
   manually monitor each domain and aggregate the performance results.
   However, it may not be precise because of the different measurement
   timing employed by each domain.

3. Requirements

   In the previous section, we discussed the current challenges and
   issues that prevent operators from offering on-demand end-to-end
   connectivity services in multi-vendor domain transport networks.

   This section provides a high-level requirement for enabling on-
   demand end-to-end connectivity services in multi-vendor domain
   transport networks in a single operator environment.

   Figure 2 shows information flow requirements of the aforementioned
   context.






























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            +-------------------------------------------------+
            |                                                 |
            |         Customer On-demand Network Service      |
            |                                                 |
            +-------------------------------------------------+
                                    /|\
                                     |
                                    \|/
            +-------------------------------------------------+
            |                                                 |
            |               Abstracted Global View            |
            |                                                 |
            +-------------------------------------------------+
                                    /|\
                                     |
                                    \|/
            +-------------------------------------------------+
            |                                                 |
            |        Single Integrated E2E Network View       |
            |                                                 |
            +-------------------------------------------------+
                  /|\              /|\               /|\
                   |                |                 |
                  \|/              \|/               \|/
            +-------------+   +-------------+   +-------------+
            |             |   |             |   |             |
            |  Domain A   |   |  Domain B   |   |  Domain C   |
            |   Control   |   |   Control   |   |   Control   |
            +-------------+   +-------------+   +-------------+


      Figure 2. Information Flow Requirements for Enabling On-demand
       Network Connectivity Service in Multi-vendor Domain Networks

   There are a number of key requirements from Figure 2.

   - A single integrated end-to-end network view is necessary to be
     able to provision the end-to-end paths that traverse multiple
     vendor domains. In this approach the scalability and
     confidentiality problems are solved, but new considerations must
     be taken into account:

        o Limited awareness, by the VNC, of the intra-domain resources
          availability.

        o Sub-optimal path selection.



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   - The path computations shall be performed in two stages: first on
     the abstracted end-to-end network view (happening at VNC), and on
     the second stage it shall be expanded by each PNC.

   - In order to create a single integrated end-to-end network view,
     discovery of inter-connection data between domains including the
     domain border nodes/links is necessary. (The entity to collect
     domain-level data is responsible for collecting inter-connection
     links/nodes)

   - The entity to collect domain-level data should recognize
     interoperability method between each domain. (There might be
     several interoperability mechanisms according to technology being
     applied.)

   - The entity responsible to collect domain-level data and create an
     integrated end-to-end view should support push/pull model with
     respect to all its interfaces.

   - The same entity should coordinate a signaling flow for end-to-end
     connections to each domain involved. (This entity to domain
     control is analogous to an NMS to EMS relationship)

   - The entity responsible to create abstract global view should
     support push/pull model with respect to all its interfaces. (Note
     that the two entities (an entity to create an integrated end-to-
     end view and an entity to create an abstracted global view) can be
     assumed by the same entity, which is an implementation issue.

   - Hierarchical composition of integrated network views should be
     enabled by a common API between NorthBound Interface of the Single
     Integrated End-to-End view (handled by VNC) and Domain Control
     (handled by PNC).

   - There is a need for a common API between each domain control to
     the entity that is responsible for creating a single integrated
     end-to-end network view. At the minimum, the following items are
     required on the API:

        o Programmability of the API.

        o The multiple levels/granularities of the abstraction of
          network resource (which is subject to policy and service
          need).

        o The abstraction of network resource should include customer
          end points and inter-domain gateway nodes/links.

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        o Any physical network constraints (such as SRLG, link
          distance, etc.) should be reflected in abstraction.

        o Domain preference and local policy (such as preferred peering
          point(s), preferred route, etc.)

        o Domain network capability (e.g., support of push/pull model).

   - The entity responsible for abstraction of a global view into a
     customer view should provide a programmable API to allow the
     flexibility. Abstraction might be provided by representing each
     domain as a virtual node (node abstraction) or a set of virtual
     nodes and links (link abstraction). Node abstraction creates a
     network topology composed by nodes representing each network
     domain and the inter-domain links between the border nodes of each
     domain.

        o Abstraction of a global view into a customer view should be
          provided to allow customer to dynamically request network on-
          demand services including connectivity services.

        o What level of details customer should be allowed to view
          network is subject to negotiation between the customer and
          the operator.



4. References

   [ACTN-Frame] D. Ceccarelli, L. Fang, Y. Lee and D. Lopez, "Framework
             for Abstraction and Control of Transport Networks," draft-
             ceccarelli-actn-framework, work in progress.

   [ACTN-PS] Y. Lee, D. King, M. Boucadair, R. Jing, and L. Murillo,
             "Problem Statement for the Abstraction and Control of
             Transport Networks," draft-leeking-actn-problem-statement,
             work in progress.


5. Acknowledgement

   The authors wish to thank Young Lee for the discussions in the
   document.







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6. Contributors

Authors' Addresses

   Kwang-koog Lee

   KT
   Email: kwangkoog.lee@kt.com

   Hosong Lee

   KT
   Email: hosong.lee@kt.com

   Ricard Vilata
   CTTC
   Email: ricard.vilalta@cttc.es

   Victor Lopez
   Telefonica
   Email: victor.lopezalvarez@telefonica.com



























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