Network Virtualization Research Challenges
draft-irtf-nfvrg-gaps-network-virtualization-10

NFVRG                                                      CJ. Bernardos
Internet-Draft                                                      UC3M
Intended status: Informational                                 A. Rahman
Expires: September 19, 2016                                   JC. Zuniga
                                                            InterDigital
                                                           LM. Contreras
                                                               P. Aranda
                                                                     TID
                                                          March 18, 2016


           Gap Analysis on Network Virtualization Activities
            draft-irtf-nfvrg-gaps-network-virtualization-00

Abstract

   The main goal of this document is to serve as a survey of the
   different efforts that have been taken and are currently taking place
   at IETF and IRTF in regards to network virtualization, automation and
   orchestration, putting them into context considering efforts by other
   SDOs, and identifying current gaps and challenges that can be tackled
   at IETF or researched at the IRTF.

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
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   This Internet-Draft will expire on September 19, 2016.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
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   This document is subject to BCP 78 and the IETF Trust's Legal
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   (http://trustee.ietf.org/license-info) in effect on the date of



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   publication of this document.  Please review these documents
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Network Function Virtualization . . . . . . . . . . . . .   5
     3.2.  Software Defined Networking . . . . . . . . . . . . . . .   7
     3.3.  Mobile Edge Computing . . . . . . . . . . . . . . . . . .  11
     3.4.  IEEE 802.1CF (OmniRAN)  . . . . . . . . . . . . . . . . .  12
     3.5.  Distributed Management Task Force . . . . . . . . . . . .  12
     3.6.  Open Source initiatives . . . . . . . . . . . . . . . . .  12
   4.  Network Virtualization at IETF/IRTF . . . . . . . . . . . . .  14
     4.1.  SDN RG  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     4.2.  SFC WG  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     4.3.  NVO3 WG . . . . . . . . . . . . . . . . . . . . . . . . .  15
     4.4.  DMM WG  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     4.5.  I2RS WG . . . . . . . . . . . . . . . . . . . . . . . . .  17
     4.6.  BESS WG . . . . . . . . . . . . . . . . . . . . . . . . .  18
     4.7.  BM WG . . . . . . . . . . . . . . . . . . . . . . . . . .  19
     4.8.  TEAS WG . . . . . . . . . . . . . . . . . . . . . . . . .  20
     4.9.  I2NSF WG  . . . . . . . . . . . . . . . . . . . . . . . .  20
     4.10. IPPM WG . . . . . . . . . . . . . . . . . . . . . . . . .  21
     4.11. NFV RG  . . . . . . . . . . . . . . . . . . . . . . . . .  22
     4.12. VNFpool BoF . . . . . . . . . . . . . . . . . . . . . . .  22
   5.  Summary of Gaps . . . . . . . . . . . . . . . . . . . . . . .  23
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  24
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  25
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  25
   9.  Informative References  . . . . . . . . . . . . . . . . . . .  25
   Appendix A.  The mobile network use case  . . . . . . . . . . . .  28
     A.1.  The 3GPP Evolved Packet System  . . . . . . . . . . . . .  28
     A.2.  Virtualizing the 3GPP EPS . . . . . . . . . . . . . . . .  30
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  30

1.  Introduction

   The telecommunications sector is experiencing a major revolution that
   will shape the way networks and services are designed and deployed
   for the next decade.  We are witnessing an explosion in the number of
   applications and services demanded by users, which are now really
   capable of accessing them on the move.  In order to cope with such a



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   demand, some network operators are looking at the cloud computing
   paradigm, which enables a potential reduction of the overall costs by
   outsourcing communication services from specific hardware in the
   operator's core to server farms scattered in datacenters.  These
   services have different characteristics if compared with conventional
   IT services that have to be taken into account in this cloudification
   process.  Also the transport network is affected in that it is
   evolving to a more sophisticated form of IP architecture with trends
   like separation of control and data plane traffic, and more fine-
   grained forwarding of packets (beyond looking at the destination IP
   address) in the network to fulfill new business and service goals.

   Virtualization of functions also provides operators with tools to
   deploy new services much faster, as compared to the traditional use
   of monolithic and tightly integrated dedicated machinery.  As a
   natural next step, mobile network operators need to re-think how to
   evolve their existing network infrastructures and how to deploy new
   ones to address the challenges posed by the increasing customers'
   demands, as well as by the huge competition among operators.  All
   these changes are triggering the need for a modification in the way
   operators and infrastructure providers operate their networks, as
   they need to significantly reduce the costs incurred in deploying a
   new service and operating it.  Some of the mechanisms that are being
   considered and already adopted by operators include: sharing of
   network infrastructure to reduce costs, virtualization of core
   servers running in data centers as a way of supporting their load-
   aware elastic dimensioning, and dynamic energy policies to reduce the
   monthly electricity bill.  However, this has proved to be tough to
   put in practice, and not enough.  Indeed, it is not easy to deploy
   new mechanisms in a running operational network due to the high
   dependency on proprietary (and sometime obscure) protocols and
   interfaces, which are complex to manage and often require configuring
   multiple devices in a decentralized way.

   Network Function Virtualization (NFV) and Software Defined Networking
   (SDN) are changing the way the telecommunications sector will deploy,
   extend and operate their networks.  This document provides a survey
   of the different efforts that have taken and are currently taking
   place at IETF and IRTF in regards of network virtualization, looking
   at how they relate to the ETSI NFV ISG, ETSI MEC ISG and ONF
   architectural frameworks.  Based on this analysis, we also go a step
   farther, identifying which are the potential work areas where IETF/
   IRTF can work on to complement the complex network virtualization map
   of technologies being standardized today.







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2.  Terminology

   The following terms used in this document are defined by the ETSI NVF
   ISG, the ONF and the IETF:

      Application Plane - The collection of applications and services
      that program network behavior.

      Control Plane (CP) - The collection of functions responsible for
      controlling one or more network devices.  CP instructs network
      devices with respect to how to process and forward packets.  The
      control plane interacts primarily with the forwarding plane and,
      to a lesser extent, with the operational plane.

      Forwarding Plane (FP) - The collection of resources across all
      network devices responsible for forwarding traffic.

      Management Plane (MP) - The collection of functions responsible
      for monitoring, configuring, and maintaining one or more network
      devices or parts of network devices.  The management plane is
      mostly related to the operational plane (it is related less to the
      forwarding plane).

      NFV Infrastructure (NFVI): totality of all hardware and software
      components which build up the environment in which VNFs are
      deployed

      NFV Management and Orchestration (NFV-MANO): functions
      collectively provided by NFVO, VNFM, and VIM.

      NFV Orchestrator (NFVO): functional block that manages the Network
      Service (NS) lifecycle and coordinates the management of NS
      lifecycle, VNF lifecycle (supported by the VNFM) and NFVI
      resources (supported by the VIM) to ensure an optimized allocation
      of the necessary resources and connectivity.

      OpenFlow protocol (OFP): allowing vendor independent programming
      of control functions in network nodes.

      Operational Plane (OP) - The collection of resources responsible
      for managing the overall operation of individual network devices.

      Service Function Chain (SFC): for a given service, the abstracted
      view of the required service functions and the order in which they
      are to be applied.  This is somehow equivalent to the Network
      Function Forwarding Graph (NF-FG) at ETSI.





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      Service Function Path (SFP): the selection of specific service
      function instances on specific network nodes to form a service
      graph through which an SFC is instantiated.

      virtual EPC (vEPC): control plane of 3GPPs EPC operated on NFV
      framework (as defined by [I-D.matsushima-stateless-uplane-vepc]).

      Virtualized Infrastructure Manager (VIM): functional block that is
      responsible for controlling and managing the NFVI compute, storage
      and network resources, usually within one operator's
      Infrastructure Domain.

      Virtualized Network Function (VNF): implementation of a Network
      Function that can be deployed on a Network Function Virtualisation
      Infrastructure (NFVI).

      Virtualized Network Function Manager (VNFM): functional block that
      is responsible for the lifecycle management of VNF.

3.  Background

3.1.  Network Function Virtualization

   The ETSI ISG NFV is a working group which, since 2012, aims to evolve
   quasi-standard IT virtualization technology to consolidate many
   network equipment types into industry standard high volume servers,
   switches, and storage.  It enables implementing network functions in
   software that can run on a range of industry standard server hardware
   and can be moved to, or loaded in, various locations in the network
   as required, without the need to install new equipment.  To date,
   ETSI NFV is by far the most accepted NFV reference framework and
   architectural footprint [etsi_nvf_whitepaper].  The ETSI NFV
   framework architecture framework is composed of three domains
   (Figure 1):

   o  Virtualized Network Function, running over the NFVI.

   o  NFV Infrastructure (NFVI), including the diversity of physical
      resources and how these can be virtualized.  NFVI supports the
      execution of the VNFs.

   o  NFV Management and Orchestration, which covers the orchestration
      and life-cycle management of physical and/or software resources
      that support the infrastructure virtualization, and the life-cycle
      management of VNFs.  NFV Management and Orchestration focuses on
      all virtualization specific management tasks necessary in the NFV
      framework.




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   +-------------------------------------------+  +---------------+
   |   Virtualized Network Functions (VNFs)    |  |               |
   |  -------   -------   -------   -------    |  |               |
   |  |     |   |     |   |     |   |     |    |  |               |
   |  | VNF |   | VNF |   | VNF |   | VNF |    |  |               |
   |  |     |   |     |   |     |   |     |    |  |               |
   |  -------   -------   -------   -------    |  |               |
   +-------------------------------------------+  |               |
                                                  |               |
   +-------------------------------------------+  |               |
   |         NFV Infrastructure (NFVI)         |  |      NFV      |
   | -----------    -----------    ----------- |  |  Management   |
   | | Virtual |    | Virtual |    | Virtual | |  |      and      |
   | | Compute |    | Storage |    | Network | |  | Orchestration |
   | -----------    -----------    ----------- |  |               |
   | +---------------------------------------+ |  |               |
   | |         Virtualization Layer          | |  |               |
   | +---------------------------------------+ |  |               |
   | +---------------------------------------+ |  |               |
   | | -----------  -----------  ----------- | |  |               |
   | | | Compute |  | Storage |  | Network | | |  |               |
   | | -----------  -----------  ----------- | |  |               |
   | |          Hardware resources           | |  |               |
   | +---------------------------------------+ |  |               |
   +-------------------------------------------+  +---------------+

                       Figure 1: ETSI NFV framework

   The NFV architectural framework identifies functional blocks and the
   main reference points between such blocks.  Some of these are already
   present in current deployments, whilst others might be necessary
   additions in order to support the virtualization process and
   consequent operation.  The functional blocks are (Figure 2):

   o  Virtualized Network Function (VNF).

   o  Element Management (EM).

   o  NFV Infrastructure, including: Hardware and virtualized resources,
      and Virtualization Layer.

   o  Virtualized Infrastructure Manager(s) (VIM).

   o  NFV Orchestrator.

   o  VNF Manager(s).

   o  Service, VNF and Infrastructure Description.



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   o  Operations and Business Support Systems (OSS/BSS).

                                                  +--------------------+
   +-------------------------------------------+  | ----------------   |
   |                 OSS/BSS                   |  | | NFV          |   |
   +-------------------------------------------+  | | Orchestrator +-- |
                                                  | ---+------------ | |
   +-------------------------------------------+  |    |             | |
   |  ---------     ---------     ---------    |  |    |             | |
   |  | EM 1  |     | EM 2  |     | EM 3  |    |  |    |             | |
   |  ----+----     ----+----     ----+----    |  | ---+----------   | |
   |      |             |             |        |--|-|    VNF     |   | |
   |  ----+----     ----+----     ----+----    |  | | manager(s) |   | |
   |  | VNF 1 |     | VNF 2 |     | VNF 3 |    |  | ---+----------   | |
   |  ----+----     ----+----     ----+----    |  |    |             | |
   +------|-------------|-------------|--------+  |    |             | |
          |             |             |           |    |             | |
   +------+-------------+-------------+--------+  |    |             | |
   |         NFV Infrastructure (NFVI)         |  |    |             | |
   | -----------    -----------    ----------- |  |    |             | |
   | | Virtual |    | Virtual |    | Virtual | |  |    |             | |
   | | Compute |    | Storage |    | Network | |  |    |             | |
   | -----------    -----------    ----------- |  | ---+------       | |
   | +---------------------------------------+ |  | |        |       | |
   | |         Virtualization Layer          | |--|-| VIM(s) +-------- |
   | +---------------------------------------+ |  | |        |         |
   | +---------------------------------------+ |  | ----------         |
   | | -----------  -----------  ----------- | |  |                    |
   | | | Compute |  | Storage |  | Network | | |  |                    |
   | | | hardware|  | hardware|  | hardware| | |  |                    |
   | | -----------  -----------  ----------- | |  |                    |
   | |          Hardware resources           | |  |  NFV Management    |
   | +---------------------------------------+ |  | and Orchestration  |
   +-------------------------------------------+  +--------------------+

                 Figure 2: ETSI NFV reference architecture

3.2.  Software Defined Networking

   The Software Defined Networking (SDN) paradigm pushes the
   intelligence currently residing in the network elements to a central
   controller implementing the network functionality through software.
   In contrast to traditional approaches, in which the network's control
   plane is distributed throughout all network devices, with SDN the
   control plane is logically centralized.  In this way, the deployment
   of new characteristics in the network no longer requires of complex
   and costly changes in equipment or firmware updates, but only a
   change in the software running in the controller.  The main advantage



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   of this approach is the flexibility it provides operators with to
   manage their network, i.e., an operator can easily change its
   policies on how traffic is distributed throughout the network.

   The most visible of the SDN protocol stacks is the OpenFlow protocol
   (OFP), which is maintained and extended by the Open Network
   Foundation (ONF: https://www.opennetworking.org/).  Originally this
   protocol was developed specifically for IEEE 802.1 switches
   conforming to the ONF OpenFlow Switch specification.  As the benefits
   of the SDN paradigm have reached a wider audience, its application
   has been extended to more complex scenarios such as Wireless and
   Mobile networks.  Within this area of work, the ONF is actively
   developing new OFP extensions addressing three key scenarios: (i)
   Wireless backhaul, (ii) Cellular Evolved Packet Core (EPC), and (iii)
   Unified access and management across enterprise wireless and fixed
   networks.



































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   +----------+
   | -------  |
   | |Oper.|  |            O
   | |Mgmt.|  |<........> -+- Network Operator
   | |Iface|  |            ^
   | -------  |      +----------------------------------------+
   |          |      | +------------------------------------+ |
   |          |      | | ---------  ---------     --------- | |
   |--------- |      | | | App 1 |  | App 2 | ... | App n | | |
   ||Plugins| |<....>| | ---------  ---------     --------- | |
   |--------- |      | | Plugins                            | |
   |          |      | +------------------------------------+ |
   |          |      | Application Plane                      |
   |          |      +----------------------------------------+
   |          |                         A
   |          |                         |
   |          |                         V
   |          |      +----------------------------------------+
   |          |      | +------------------------------------+ |
   |--------- |      | |     ------------  ------------     | |
   || Netw. | |      | |     | Module 1 |  | Module 2 |     | |
   ||Engine | |<....>| |     ------------  ------------     | |
   |--------- |      | | Network Engine                     | |
   |          |      | +------------------------------------+ |
   |          |      | Controller Plane                       |
   |          |      +----------------------------------------+
   |          |                         A
   |          |                         |
   |          |                         V
   |          |      +----------------------------------------+
   |          |      |  +--------------+   +--------------+   |
   |          |      |  | ------------ |   | ------------ |   |
   |----------|      |  | | OpenFlow | |   | | OpenFlow | |   |
   ||OpenFlow||<....>|  | ------------ |   | ------------ |   |
   |----------|      |  | NE           |   | NE           |   |
   |          |      |  +--------------+   +--------------+   |
   |          |      | Data Plane                             |
   |Management|      +----------------------------------------+
   +----------+

                 Figure 3: High level SDN ONF architecture

   Figure 3 shows the blocks and the functional interfaces of the ONF
   architecture, which comprises three planes: Data, Controller, and
   Application.  The Data plane comprehends several Network Entities
   (NE), which expose their capabilities toward the Controller plane via
   a Southbound API.  The Controller plane includes several cooperating
   modules devoted to the creation and maintenance of an abstracted



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   resource model of the underneath network.  Such model is exposed to
   the applications via a Northbound API where the Application plane
   comprises several applications/services, each of which has exclusive
   control of a set of exposed resources.

   The Management plane spans its functionality across all planes
   performing the initial configuration of the network elements in the
   Data plane, the assignment of the SDN controller and the resources
   under its responsibility.  In the Controller plane, the Management
   needs to configure the policies defining the scope of the control
   given to the SDN applications, to monitor the performance of the
   system, and to configure the parameters required by the SDN
   controller modules.  In the Application plane, Management configures
   the parameters of the applications and the service level agreements.
   In addition to the these interactions, the Management plane exposes
   several functions to network operators which can easily and quickly
   configure and tune the network at each layer.

   The SDNRG has documented a reference layer model in RFC7426
   [RFC7426], which is reproduced in Figure 4.  This model structures
   SDN in planes and layers which are glued together by different
   abstraction layers.  This architecture differentiates between the
   control and the management planes and provides for differentiated
   southbound interfaces (SBIs).



























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                  o--------------------------------o
                  |                                |
                  | +-------------+   +----------+ |
                  | | Application |   |  Service | |
                  | +-------------+   +----------+ |
                  |       Application Plane        |
                  o---------------Y----------------o
                                  |
    *-----------------------------Y---------------------------------*
    |           Network Services Abstraction Layer (NSAL)           |
    *------Y------------------------------------------------Y-------*
           |                                                |
           |               Service Interface                |
           |                                                |
    o------Y------------------o       o---------------------Y------o
    |      |    Control Plane |       | Management Plane    |      |
    | +----Y----+   +-----+   |       |  +-----+       +----Y----+ |
    | | Service |   | App |   |       |  | App |       | Service | |
    | +----Y----+   +--Y--+   |       |  +--Y--+       +----Y----+ |
    |      |           |      |       |     |               |      |
    | *----Y-----------Y----* |       | *---Y---------------Y----* |
    | | Control Abstraction | |       | | Management Abstraction | |
    | |     Layer (CAL)     | |       | |      Layer (MAL)       | |
    | *----------Y----------* |       | *----------Y-------------* |
    |            |            |       |            |               |
    o------------|------------o       o------------|---------------o
                 |                                 |
                 | CP                              | MP
                 | Southbound                      | Southbound
                 | Interface                       | Interface
                 |                                 |
    *------------Y---------------------------------Y----------------*
    |         Device and resource Abstraction Layer (DAL)           |
    *------------Y---------------------------------Y----------------*
    |            |                                 |                |
    |    o-------Y----------o   +-----+   o--------Y----------o     |
    |    | Forwarding Plane |   | App |   | Operational Plane |     |
    |    o------------------o   +-----+   o-------------------o     |
    |                       Network Device                          |
    +---------------------------------------------------------------+

                     Figure 4: SDN Layer Architecture

3.3.  Mobile Edge Computing

   Mobile Edge Computing capabilities deployed in the edge of the mobile
   network can facilitate the efficient and dynamic provision of
   services to mobile users.  The ETSI ISG MEC working group, operative



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   from end of 2014, intends to specify an open environment for
   integrating MEC capabilities with service providers networks,
   including also applications from 3rd parties.  These distributed
   computing capabilities will make available IT infrastructure as in a
   cloud environment for the deployment of functions in mobile access
   networks.  It can be seen then as a complement to both NFV and SDN.

3.4.  IEEE 802.1CF (OmniRAN)

   The IEEE 802.1CF Recommended Practice specifies an access network,
   which connects terminals to their access routers, utilizing
   technologies based on the family of IEEE 802 Standards (e.g., 802.3
   Ethernet, 802.11 Wi-Fi, etc.).  The specification defines an access
   network reference model, including entities and reference points
   along with behavioral and functional descriptions of communications
   among those entities.

   The goal of this project is to help unifying the support of different
   interfaces, enabling shared network control and use of software
   defined network (SDN) principles, thereby lowering the barriers to
   new network technologies, to new network operators, and to new
   service providers.

3.5.  Distributed Management Task Force

   The DMTF is an industry standards organization working to simplify
   the manageability of network-accessible technologies through open and
   collaborative efforts by some technology companies.  The DMTF is
   involved in the creation and adoption of interoperable management
   standards, supporting implementations that enable the management of
   diverse traditional and emerging technologies including cloud,
   virtualization, network and infrastructure.

   There are several DMTF initiatives that are relevant to the network
   virtualization area, such as the Open Virtualization Format (OVF),
   for VNF packaging; the Cloud Infrastructure Management Interface
   (CIM), for cloud infrastructure management; the Network Management
   (NETMAN), for VNF management; and, the Virtualization Management
   (VMAN), for virtualization infrastructure management.

3.6.  Open Source initiatives

   The Open Source community is especially active in the area of network
   virtualization.  We next summarize some of the active efforts:

   o  OpenStack.  OpenStack is a free and open-source cloud-computing
      software platform.  OpenStack software controls large pools of




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      compute, storage, and networking resources throughout a
      datacenter, managed through a dashboard or via the OpenStack API.

   o  OpenDayLight.  OpenDaylight (ODL) is a highly available, modular,
      extensible, scalable and multi-protocol controller infrastructure
      built for SDN deployments on modern heterogeneous multi-vendor
      networks.  It provides a model-driven service abstraction platform
      that allows users to write apps that easily work across a wide
      variety of hardware and southbound protocols.

   o  ONOS.  The ONOS (Open Network Operating System) project is an open
      source community hosted by The Linux Foundation.  The goal of the
      project is to create a software-defined networking (SDN) operating
      system for communications service providers that is designed for
      scalability, high performance and high availability.

   o  OpenContrail.  OpenContrail is an Apache 2.0-licensed project that
      is built using standards-based protocols and provides all the
      necessary components for network virtualization-SDN controller,
      virtual router, analytics engine, and published northbound APIs.
      It has an extensive REST API to configure and gather operational
      and analytics data from the system.

   o  OPNFV.  OPNFV is a carrier-grade, integrated, open source platform
      to accelerate the introduction of new NFV products and services.
      By integrating components from upstream projects, the OPNFV
      community aims at conducting performance and use case-based
      testing to ensure the platform's suitability for NFV use cases.
      The scope of OPNFV's initial release is focused on building NFV
      Infrastructure (NFVI) and Virtualized Infrastructure Management
      (VIM) by integrating components from upstream projects such as
      OpenDaylight, OpenStack, Ceph Storage, KVM, Open vSwitch, and
      Linux.  These components, along with application programmable
      interfaces (APIs) to other NFV elements form the basic
      infrastructure required for Virtualized Network Functions (VNF)
      and Management and Network Orchestration (MANO) components.
      OPNFV's goal is to increase performance and power efficiency;
      improve reliability, availability, and serviceability; and deliver
      comprehensive platform instrumentation.

   o  OSM.  Open Source Mano (OSM) is an ETSI-hosted project to develop
      an Open Source NFV Management and Orchestration (MANO) software
      stack aligned with ETSI NFV.  OSM is based on components from
      previous projects, such Telefonica's OpenMANO or Canonical's Juju,
      among others.

   o  OpenBaton.  OpenBaton is a ETSI NFV compliant Network Function
      Virtualization Orchestrator (NFVO).  OpenBaton was part of the



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      OpenSDNCore project started with the objective of providing a
      compliant implementation of the ETSI NFV specification.

   Among the main areas that are being developed by the former open
   source activities that related to network virtualization research, we
   can highlight: policy-based resource management, analytics for
   visibility and orchestration, service verification with regards to
   security and resiliency.

4.  Network Virtualization at IETF/IRTF

4.1.  SDN RG

   The SDNRG provides the grounds for an open-minded investigation of
   Software Defined Networking.  They aim at identifying approaches that
   can be defined and used in the near term as well as the research
   challenges in the field.  As such, they SDNRG will not define
   standards, but provide inputs to standards defining and standards
   producing organizations.

   It is working on classifying SDN models, including definitions and
   taxonomies.  It is also studying complexity, scalability and
   applicability of the SDN model.  Additionally, the SDNRG is working
   on network description languages (and associated tools), abstractions
   and interfaces.  They also investigate the verification of correct
   operation of network or node function.

   The SDNRG has produced a reference layer model RFC7426 [RFC7426],
   which structures SDNs in planes and layers which are glued together
   by different abstraction layers.  This architecture differentiates
   between the control and the management planes and provides for
   differentiated southbound interfaces (SBIs).

4.2.  SFC WG

   Current network services deployed by operators often involve the
   composition of several individual functions (such as packet
   filtering, deep packet inspection, load balancing).  These services
   are typically implemented by the ordered combination of a number of
   service functions that are deployed at different points within a
   network, not necessary on the direct data path.  This requires
   traffic to be steered through the required service functions,
   wherever they are deployed.

   For a given service, the abstracted view of the required service
   functions and the order in which they are to be applied is called a
   Service Function Chain (SFC), which is called Network Function
   Forwarding Graph (NF-FG) in ETSI.  An SFC is instantiated through



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   selection of specific service function instances on specific network
   nodes to form a service graph: this is called a Service Function Path
   (SFP).  The service functions may be applied at any layer within the
   network protocol stack (network layer, transport layer, application
   layer, etc.).

   The SFC working group is working on an architecture for service
   function chaining that includes the necessary protocols or protocol
   extensions to convey the Service Function Chain and Service Function
   Path information to nodes that are involved in the implementation of
   service functions and Service Function Chains, as well as mechanisms
   for steering traffic through service functions.

   In terms of actual work items, the SFC WG is chartered to deliver:
   (i) a problem statement document [RFC7498], (ii) an architecture
   document [RFC7665], (iii) a service-level data plane encapsulation
   format (the encapsulation should indicate the sequence of service
   functions that make up the Service Function Chain, specify the
   Service Function Path, and communicate context information between
   nodes that implement service functions and Service Function Chains),
   and (iv) a document describing requirements for conveying information
   between control or management elements and SFC implementation points.

   Potential gap: as stated in the SFC charter, any work on the
   management and configuration of SFC components related to the support
   of Service Function Chaining will not be done yet, until better
   understood and scoped.  This part is of special interest for
   operators and would be required in order to actually put SFC
   mechanisms into operation.

   Potential gap: redundancy and reliability mechanisms are currently
   not dealt with by any WG in the IETF.  While this has been the main
   goal of the VNFpool BoF efforts, it still remains un-addressed.

4.3.  NVO3 WG

   The Network Virtualization Overlays (NVO3) WG is developing protocols
   that enable network virtualization overlays within large Data Center
   (DC) environments.  Specifically NVO3 assumes an underlying physical
   Layer 3 (IP) fabric on which multiple tenant networks are virtualized
   on top (i.e. overlays).  With overlays, data traffic between tenants
   is tunneled across the underlying DC's IP network.  The use of
   tunnels provides a number of benefits by decoupling the network as
   viewed by tenants from the underlying physical network across which
   they communicate [I-D.ietf-nvo3-arch].

   Potential gap: It would be worthwhile to see if some of the specific
   approaches developed in this WG (e.g. overlays, traffic isolation, VM



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   migration) can be applied outside the DC, and specifically if they
   can be applicable to network virtualization (NFV).  These approaches
   would be most relevant to the ETSI Network Function Virtualization
   Infrastructure (NFVI), and the Virtualized Infrastructure Manager
   part of the MANO.

4.4.  DMM WG

   The Distributed Mobility Management (DMM) WG is looking at solutions
   for IP networks that enable traffic between mobile and correspondent
   nodes taking an optimal route, preventing some of the issues caused
   by the use of centralized mobility solutions, which anchor all the
   traffic at a given node (or a very limited set of nodes).  The DMM WG
   is considering the latest developments in mobile networking research
   and operational practices (i.e., flattening network architectures,
   the impact of virtualization, new deployment needs as wireless access
   technologies evolve in the coming years) and aims at describing how
   distributed mobility management addresses the new needs in this area
   better than previously standardized solutions.

   Although network virtualization is not the main area of the DMM work,
   the impact of SDN and NFV mechanisms is clear on the work that is
   currently being done in the WG.  One example is architecture defined
   for the virtual Evolved Packet Core (vEPC) in
   [I-D.matsushima-stateless-uplane-vepc].  Here, the authors describe a
   particular realization of the vEPC concept, which is designed to
   support NFV.  In the defined architecture, the user plane of EPC is
   decoupled from the control-plane and uses routing information to
   forward packets of mobile nodes.  This proposal does not modify the
   signaling of the EPC control plane, although the EPC control plane
   runs on an hypervisor.

   Potential gap: in a vEPC/DMM context, how to run the EPC control
   plane on NFV.

   The DMM WG is also looking at ways to supporting the separation of
   the Control-Plane for mobility- and session management from the
   actual Data-Plane [I-D.ietf-dmm-fpc-cpdp].  The protocol semantics
   being defined abstract from the actual details for the configuration
   of Data-Plane nodes and apply between a Client function, which is
   used by an application of the mobility Control-Plane, and an Agent
   function, which is associated with the configuration of Data-Plane
   nodes according to the policies issued by the mobility Control-Plane.

   Potential gap: the actual mappings between these generic protocol
   semantics and the configuration commands required on the data plane
   network elements are not in the scope of this document, and are




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   therefore a potential gap that will need to be addressed (e.g., for
   OpenFlow switches).

4.5.  I2RS WG

   The Interface to the Routing System (I2RS) WG is developing a high-
   level architecture that describes the basic building-blocks to access
   the routing system through a set of protocol-based control or
   management interfaces.  This architecture, as described in
   [I-D.ietf-i2rs-architecture], comprises an I2RS Agent as a unified
   interface that is accessed by I2RS clients using the I2RS protocol.
   The client is controlled by one or more network applications and
   accesses one or more agents, as shown in the following figure:

          ******************   *****************  *****************
          *  Application C *   * Application D *  * Application E *
          ******************   *****************  *****************
                   |                  |                  |
                   +--------------+   |    +-------------+
                                  |   |    |
                                ***************
                                *  Client P   *----------------------+
                                ***************                      |
   ***********************          |                                |
   *    Application A    *          |                                |
   *                     *          |       ***********************  |
   *  +----------------+ *          |       *    Application B    *  |
   *  |   Client A     | *          |       *                     *  |
   *  +----------------+ *          |       *  +----------------+ *  |
   ***********************          |       *  |   Client B     | *  |
             |                      |       *  +----------------+ *  |
             |     +----------------+       ***********************  |
             |     |                              |        |         |
             |     |     +------------------------+        |   +-----+
             |     |     |                                 |   |
      *******************************   *******************************
      *                             *   *                             *
      *      Routing Element 1      *   *      Routing Element 2      *
      *                             *   *                             *
      *******************************   *******************************

                  Figure 5: High level I2RS architecture

   Routing elements consist of an agent that communicates with the
   client or clients driven by the applications and accesses the
   different subsystems in the element as shown in the following figure:





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                      |
     *****************v**************
     *  +---------------------+     *
     *  |       Agent         |     *
     *  +---------------------+     *
     *     ^        ^  ^   ^        *
     *     |        |  |   |        *
     *     |        |  |   +--+     *
     *     |        |  |      |     *
     *     v        |  |      v     *
     * +---+-----+  |  | +----+---+ *
     * | Routing |  |  | | Local  | *
     * |   and   |  |  | | Config | *
     * |Signaling|  |  | +--------+ *
     * +---------+  |  |      ^     *
     *    ^         |  |      |     *
     *    |    +----+  |      |     *
     *    v    v       v      v     *
     *  +----------+ +------------+ *
     *  |  Dynamic | |   Static   | *
     *  |  System  | |   System   | *
     *  |  State   | |   State    | *
     *  +----------+ +------------+ *
     *                              *
     *       Routing Element        *
     ********************************

                Figure 6: Architecture of a routing element

   The I2RS architecture proposes to use model-driven APIs.  Services
   can correspond to different data-models and agents can indicate which
   model they support.

   Potential gap: network virtualization is not the main aim of the I2RS
   WG.  However, they provide an infrastructure that can be part of an
   SDN deployment.

4.6.  BESS WG

   BGP is already used as a protocol for provisioning and operating
   Layer-3 (routed) Virtual Private Networks (L3VPNs).  The BGP Enabled
   Services (BESS) working group is responsible for defining,
   specifying, and extending network services based on BGP.  In
   particular, the working group will work on the following services:

   o  BGP-enabled VPN solutions for use in the data center networking.
      This work includes consideration of VPN scaling issues and
      mechanisms applicable to such environments.



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   o  Extensions to BGP-enabled VPN solutions for the construction of
      virtual topologies in support of services such as Service Function
      Chaining.

   Potential gap: The most relevant activity in BESS that would be
   worthwhile to investigate for relevance to network virtualization
   (NFV) is the extensions to BGP-enabled VPN solutions to support of
   Service Function Chaining [I-D.rfernando-bess-service-chaining].

4.7.  BM WG

   The Benchmarking Methodology Working Group (BMWG) provides
   recommendations concerning the key performance characteristics of
   internetworking technologies, or benchmarks for network devices,
   systems, and services.  The scope of BMWG includes benchmarks for the
   management, control, and forwarding planes, and is.

   The main distinguishing characteristic of BMWG from other IETF
   measurement initiatives like the IPPM WG is that BMWG is limited to
   characterization of implementations using controlled stimuli in a lab
   environment.  The BMWG does not attempt to produce benchmarks for
   live, operational networks.

   As part of the tasks of the BMWG, it is explicitly tasked to develop
   benchmarks and methodologies for VNF and related infrastructure
   benchmarking, Benchmarking Methodologies have reliably characterized
   many physical devices.  This work item extends and enhances the
   methods to virtual network functions (VNF) and their unique
   supporting infrastructure.  The first deliverable from this activity
   mentioned in the charter of the WG is a document
   [I-D.ietf-bmwg-virtual-net] that considers the new benchmarking space
   to ensure that common issues are recognized from the start, using
   background materials from industry and SDOs (e.g., IETF, ETSI NFV).
   This document investigates the additional methodological
   considerations necessary when benchmarking VNFs instantiated and
   hosted in general-purpose hardware.  The approach is to benchmark
   physical and virtual network functions in the same way when possible,
   thereby allowing direct comparison.  Also defining benchmarking
   combinations of physical and virtual devices in a System Under Test.

   Benchmarks for platform capacity and performance characteristics of
   virtual routers, switches, and related components will be also
   addressed, including comparisons between physical and virtual network
   functions.  In many cases, the traditional benchmarks should be
   applicable to VNFs, but the lab set-ups, configurations, and
   measurement methods will likely need to be revised or enhanced.





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   There are additional documents of the BMWG relevant to the
   virtualization area, such as:
   [I-D.ietf-bmwg-sdn-controller-benchmark-term],
   [I-D.ietf-bmwg-sdn-controller-benchmark-meth], [I-D.kim-bmwg-ha-nfvi]
   and [I-D.vsperf-bmwg-vswitch-opnfv].

4.8.  TEAS WG

   Transport network infrastructure provides end-to-end connectivity for
   networked applications and services.  Network virtualization
   facilitates effective sharing (or 'slicing') of physical
   infrastructure by representing resources and topologies via
   abstractions, even in a multi-administration, multi-vendor, multi-
   technology environment.  In this way, it becomes possible to operate,
   control and manage multiple physical networks elements as single
   virtualized network.  The users of such virtualized network can
   control the allocated resources in an optimal and flexible way,
   better adapting to the specific circumstances of higher layer
   applications.

   Abstraction and Control of Transport Networks (ACTN) intends to
   define methods and capabilities for the deployment and operation of
   transport network resources [I-D.ceccarelli-teas-actn-framework].
   This activity is currently being carried out within the Traffic
   Engineering Architecture and Signaling (TEAS) WG.

   Several use cases are being proposed for both fixed and mobile
   scenarios [I-D.leeking-teas-actn-problem-statement].

   Potential gap: Several use cases in ACTN are relevant to network
   virtualization (NFV) in mobile environments.  Control of multi-tenant
   mobile backhaul transport networks, mobile virtual network operation,
   etc, can be influenced by the location of the network functions.  A
   control architecture allowing for inter-operation of NFV and
   transport network (e.g., for combined optimization) is one relevant
   area for research.

4.9.  I2NSF WG

   The I2NSF WG at defining interfaces to the flow based network
   security functions (NSFs) hosted by service providers at different
   premises.  Network Security Function (NSF) is to ensure integrity,
   confidentiality and availability of network communications, to detect
   unwanted activity, and to block it or at least mitigate its effects.
   NSFs are provided and consumed in increasingly diverse environments.
   Users of NSFs could consume network security services hosted by one
   or more providers, which may be their own enterprise, service




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   providers, or a combination of both.  The NSFs may be provided by
   physical and/or virtualized infrastructure.

   Without standard interfaces to express, monitor, and control security
   policies that govern the behavior of NSFs, it becomes virtually
   impossible for security service providers to automate their service
   offerings that utilize different security functions from multiple
   vendors.  Based on this, the main goal of I2NSF is to define an
   information model, a set of software interfaces and data models for
   controlling and monitoring aspects of NSFs (both physical and
   virtual) [I-D.jeong-i2nsf-sdn-security-services].

   Since different security vendors may support different features and
   functions on their devices, I2NSF focuses on flow based NSFs that
   provide treatment to packets/flow.

   The I2NSF WG's target deliverables include: (i) a use cases, problem
   statement, gap analysis document, (ii) a framework document,
   presenting an overview of the use of NSFs and the purpose of the
   models developed by the WG, (iii) a single, unified, Information
   Model for controlling and monitoring flow-based NSFs, (iv) the
   corresponding YANG Data Models derived from the Information Model,
   (v) a vendor-neutral vocabulary to enable the characteristics and
   behavior of NSFs to be specified without requiring the NSFs
   themselves to be standardized, and (vi) an examination of existing
   secure communication mechanisms to identify the appropriate ones for
   carrying the controlling and monitoring information between the NSFs
   and their management entities.  The WG is also targeted to work
   closely with I2RS, Netconf and Netmod WGs, as well as to communicate
   with external SDOs like ETSI NFV.

   Potential gap: aspects of NSFs such as device or network provisioning
   and configuration are out of scope.

   Potential gap: the use of SDN tools to interact with security
   functions is not explictly considered, but seems a potential
   approach, as for example described for the particular case of IPsec
   flow protection in [I-D.abad-sdnrg-sdn-ipsec-flow-protection].

4.10.  IPPM WG

   The IP Performance Metrics (IPPM) WG defines metrics that can be used
   to measure the quality and performance of Internet services and
   applications running over transport layer protocols (e.g.  TCP, UPD)
   over IP.  It also develops and maintains protocols for the
   measurement of these metrics.  The IPPM WG is a long running WG that
   started in 1997.  The architecture (framework) for IPPM WG metrics
   and associated protocols are defined in RFC 2330 [RFC2330].  Some



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   examples of recent output by IPPM WG include "A Reference Path and
   Measurement Points for Large-Scale Measurement of Broadband
   Performance" (RFC 7398 [RFC7398]) and "Framework for TCP Throughput
   Testing" (RFC 6349 [RFC6349]).

   The IPPM WG currently does not have a charter item or active drafts
   related to the topic of network virtualization.  On the automation
   and orchestration side, there is an ongoing effort
   [I-D.cmzrjp-ippm-twamp-yang] to define a YANG model for the IPPM
   protocol.

   Potential gap: There is a pressing need to define metrics and
   associated protocols to measure the performance of NFV.
   Specifically, since NFV is based on the concept of taking centralized
   functions and evolving it to highly distributed SW functions, there
   is a commensurate need to fully understand and measure the baseline
   performance of such systems.  A potential topic for the IPPM WG is
   defining packet delay, throughput, and test framework for the
   application traffic flowing through the NFVI.

4.11.  NFV RG

   The NFVRG focuses on research problems associated with virtualization
   of fixed and mobile network infrastructures, new network
   architectures based on virtualized network functions, virtualization
   of the home and enterprise network environments, co-existence with
   non-virtualized infrastructure and services, and application to
   growing areas of concern such as Internet of Things (IoT) and next
   generation content distribution.  Another goal of the NFVRG is to
   bring a research community together that can jointly address such
   problems, concentrating on problems that relate not just to
   networking but also to computing and storage constraints in such
   environments.

   Since the NFVRG is a research group, it has a wide scope.  In order
   to keep the focus, the group has identified some near term work
   items: (i) Policy based Resource Management, (ii) Analytics for
   Visibility and Orchestration, (iii) Virtual Network Function (VNF)
   Performance Modelling to facilitate transition to NFV and (iv)
   Security and Service Verification.

4.12.  VNFpool BoF

   The VNFPOOL BoF proposed to work on the way to group Virtual Network
   Function (VNF) into pools to improve resilience, provide better
   scale-out and scale-in characteristics, implement stateful failover
   among VNF members of a pool, etc.  Additionally, they propose to
   create VNF sets from VNF pools.  For this, the BoF proposed to study



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   signaling (both between members of a pool and across pools), state
   sharing mechanisms between members of a VNFPOOL, the exchange of
   reliability information between VNF sets, their users and the
   underlying network, and the reliability and security of the control
   plane needed to transport the exchanged information.

   The use cases initially considered by VNFPOOL include Content Deliver
   Networks (CDNs), the LTE mobile core network and reliable server
   pooling.  The VNFPOOL work has been dropped in the IETF.

   Potential gap: VNFPOOL tried to introduce and manage resilience in
   virtualized networking environments and therefore addresses a
   desirable feature for any software defined network.  VNFPOOL has also
   been integrated into the NFV architecture
   [I-D.bernini-nfvrg-vnf-orchestration].

5.  Summary of Gaps

   Potential Gap-1: as stated in the SFC charter, any work on the
   management and configuration of SFC components related to the support
   of Service Function Chaining will not be done yet, until better
   understood and scoped.  This part is of special interest for
   operators and would be required in order to actually put SFC
   mechanisms into operation.

   Potential Gap-2: redundancy and reliability mechanisms are currently
   not dealt with by SFC or any other WG in the IETF.  While this has
   been the main goal of the VNFpool BoF efforts, since VNFPOOL work has
   been dropped for the time being without any WG being chartered, the
   technical topics it aimed at targetting still remain un-addressed.

   Potential Gap-3: it would be worthwhile to see if some of the
   specific approaches developed in the NVO3 WG (e.g. overlays, traffic
   isolation, VM migration) can be applied outside the DC, and
   specifically if they can be applicable to network virtualization
   (NFV).  These approaches would be most relevant to the ETSI Network
   Function Virtualization Infrastructure (NFVI), and the Virtualized
   Infrastructure Manager part of the MANO.

   Potential Gap-4: the most relevant activity in BESS that would be
   worthwhile to investigate for relevance to network virtualization
   (NFV) is the extensions to BGP-enabled VPN solutions to support of
   Service Function Chaining.

   Potential Gap-5: in a vEPC/DMM context, how to run the EPC control
   plane on NFV.





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   Potential Gap-6: in DMM, on the work item addressing the separation
   of the Control-Plane for mobility- and session management from the
   actual Data-Plane, the actual mappings between these generic protocol
   semantics and the configuration commands required on the data plane
   network elements (e.g., OpenFlow switches) are not currently in the
   scope of the DMM WG.

   Potential Gap-7: network virtualization is not the main aim of the
   I2RS WG.  However, they provide an infrastructure that can be part of
   an SDN deployment.

   Potential Gap-8: VNFPOOL tries to introduce and manage resilience in
   virtualized networking environments and therefore addresses a
   desirable feature for any software defined network.  VNFPOOL has also
   been integrated into the NFV architecture
   [I-D.bernini-nfvrg-vnf-orchestration].

   Potential Gap-9: within the Traffic Engineering Architecture and
   Signaling (TEAS) WG, several use cases in ACTN are relevant to
   network virtualization (NFV) in mobile environments.  Control of
   multi-tenant mobile backhaul transport networks, mobile virtual
   network operation, etc, can be influenced by the location of the
   network functions.  A control architecture allowing for inter-
   operation of NFV and transport network (e.g., for combined
   optimization) is one relevant area for research.

   Potential Gap-10: within I2NSF', aspects of NSFs such as device or
   network provisioning and configuration are out of scope.

   Potential Gap-11: the use of SDN tools to interact with security
   functions is not explictly considered in I2NSF, but seems a potential
   approach, as for example described for the particular case of IPsec
   flow protection in [I-D.abad-sdnrg-sdn-ipsec-flow-protection].

   Potential Gap-12: there is a pressing need to define metrics and
   associated protocols to measure the performance of NFV.
   Specifically, since NFV is based on the concept of taking centralized
   functions and evolving it to highly distributed SW functions, there
   is a commensurate need to fully understand and measure the baseline
   performance of such systems.  A potential topic for the IPPM WG is
   defining packet delay, throughput, and test framework for the
   application traffic flowing through the NFVI.

6.  IANA Considerations

   N/A.





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7.  Security Considerations

   TBD.

8.  Acknowledgments

   The authors want to thank Dirk von Hugo, Rafa Marin, Diego Lopez,
   Ramki Krishnan, Kostas Pentikousis, Rana Pratap Sircar and Alfred
   Morton for their very useful reviews and comments to the document.

   The work of Pedro Aranda is supported by the European FP7 Project
   Trilogy2 under grant agreement 317756.

9.  Informative References

   [I-D.abad-sdnrg-sdn-ipsec-flow-protection]
              Abad-Carrascosa, A., Lopez, R., and G. Lopez-Millan,
              "Software-Defined Networking (SDN)-based IPsec Flow
              Protection", draft-abad-sdnrg-sdn-ipsec-flow-protection-01
              (work in progress), October 2015.

   [I-D.bernini-nfvrg-vnf-orchestration]
              Bernini, G., Maffione, V., Lopez, D., and P. Aranda, "VNF
              Pool Orchestration For Automated Resiliency in Service
              Chains", draft-bernini-nfvrg-vnf-orchestration-01 (work in
              progress), October 2015.

   [I-D.ceccarelli-teas-actn-framework]
              Ceccarelli, D. and Y. Lee, "Framework for Abstraction and
              Control of Traffic Engineered Networks", draft-ceccarelli-
              teas-actn-framework-01 (work in progress), March 2016.

   [I-D.cmzrjp-ippm-twamp-yang]
              Civil, R., Morton, A., Zheng, L., Rahman, R.,
              Jethanandani, M., and K. Pentikousis, "Two-Way Active
              Measurement Protocol (TWAMP) Data Model", draft-cmzrjp-
              ippm-twamp-yang-02 (work in progress), October 2015.

   [I-D.ietf-bmwg-sdn-controller-benchmark-meth]
              Vengainathan, B., Basil, A., Tassinari, M., Manral, V.,
              and S. Banks, "Benchmarking Methodology for SDN Controller
              Performance", draft-ietf-bmwg-sdn-controller-benchmark-
              meth-00 (work in progress), October 2015.








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   [I-D.ietf-bmwg-sdn-controller-benchmark-term]
              Vengainathan, B., Basil, A., Tassinari, M., Manral, V.,
              and S. Banks, "Terminology for Benchmarking SDN Controller
              Performance", draft-ietf-bmwg-sdn-controller-benchmark-
              term-00 (work in progress), October 2015.

   [I-D.ietf-bmwg-virtual-net]
              Morton, A., "Considerations for Benchmarking Virtual
              Network Functions and Their Infrastructure", draft-ietf-
              bmwg-virtual-net-01 (work in progress), September 2015.

   [I-D.ietf-dmm-fpc-cpdp]
              Liebsch, M., Matsushima, S., Gundavelli, S., and D. Moses,
              "Protocol for Forwarding Policy Configuration (FPC) in
              DMM", draft-ietf-dmm-fpc-cpdp-01 (work in progress), July
              2015.

   [I-D.ietf-i2rs-architecture]
              Atlas, A., Halpern, J., Hares, S., Ward, D., and T.
              Nadeau, "An Architecture for the Interface to the Routing
              System", draft-ietf-i2rs-architecture-13 (work in
              progress), February 2016.

   [I-D.ietf-nvo3-arch]
              Black, D., Hudson, J., Kreeger, L., Lasserre, M., and T.
              Narten, "An Architecture for Overlay Networks (NVO3)",
              draft-ietf-nvo3-arch-04 (work in progress), October 2015.

   [I-D.jeong-i2nsf-sdn-security-services]
              Jeong, J., Kim, H., Jung-Soo, P., Ahn, T., and s.
              sehuilee@kt.com, "Software-Defined Networking Based
              Security Services using Interface to Network Security
              Functions", draft-jeong-i2nsf-sdn-security-services-04
              (work in progress), March 2016.

   [I-D.kim-bmwg-ha-nfvi]
              Kim, T. and E. Paik, "Considerations for Benchmarking High
              Availability of NFV Infrastructure", draft-kim-bmwg-ha-
              nfvi-00 (work in progress), October 2015.

   [I-D.leeking-teas-actn-problem-statement]
              Lee, Y., King, D., Boucadair, M., Jing, R., and L.
              Contreras, "Problem Statement for Abstraction and Control
              of Transport Networks", draft-leeking-teas-actn-problem-
              statement-00 (work in progress), June 2015.






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   [I-D.matsushima-stateless-uplane-vepc]
              Matsushima, S. and R. Wakikawa, "Stateless user-plane
              architecture for virtualized EPC (vEPC)", draft-
              matsushima-stateless-uplane-vepc-05 (work in progress),
              September 2015.

   [I-D.rfernando-bess-service-chaining]
              Fernando, R., Rao, D., Fang, L., Napierala, M., So, N.,
              and A. Farrel, "Virtual Topologies for Service Chaining in
              BGP/IP MPLS VPNs", draft-rfernando-bess-service-
              chaining-01 (work in progress), April 2015.

   [I-D.vsperf-bmwg-vswitch-opnfv]
              Tahhan, M., O'Mahony, B., and A. Morton, "Benchmarking
              Virtual Switches in OPNFV", draft-vsperf-bmwg-vswitch-
              opnfv-01 (work in progress), October 2015.

   [RFC2330]  Paxson, V., Almes, G., Mahdavi, J., and M. Mathis,
              "Framework for IP Performance Metrics", RFC 2330, DOI
              10.17487/RFC2330, May 1998,
              <http://www.rfc-editor.org/info/rfc2330>.

   [RFC6349]  Constantine, B., Forget, G., Geib, R., and R. Schrage,
              "Framework for TCP Throughput Testing", RFC 6349, DOI
              10.17487/RFC6349, August 2011,
              <http://www.rfc-editor.org/info/rfc6349>.

   [RFC7398]  Bagnulo, M., Burbridge, T., Crawford, S., Eardley, P., and
              A. Morton, "A Reference Path and Measurement Points for
              Large-Scale Measurement of Broadband Performance", RFC
              7398, DOI 10.17487/RFC7398, February 2015,
              <http://www.rfc-editor.org/info/rfc7398>.

   [RFC7426]  Haleplidis, E., Ed., Pentikousis, K., Ed., Denazis, S.,
              Hadi Salim, J., Meyer, D., and O. Koufopavlou, "Software-
              Defined Networking (SDN): Layers and Architecture
              Terminology", RFC 7426, DOI 10.17487/RFC7426, January
              2015, <http://www.rfc-editor.org/info/rfc7426>.

   [RFC7498]  Quinn, P., Ed. and T. Nadeau, Ed., "Problem Statement for
              Service Function Chaining", RFC 7498, DOI 10.17487/
              RFC7498, April 2015,
              <http://www.rfc-editor.org/info/rfc7498>.

   [RFC7665]  Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
              Chaining (SFC) Architecture", RFC 7665, DOI 10.17487/
              RFC7665, October 2015,
              <http://www.rfc-editor.org/info/rfc7665>.



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   [etsi_nvf_whitepaper]
              "Network Functions Virtualisation (NFV). White Paper 2",
              October 2014.

Appendix A.  The mobile network use case

A.1.  The 3GPP Evolved Packet System

   TBD.  This will include a high level summary of the 3GPP EPS
   architecture, detailing both the EPC (core) and the RAN (access)
   parts.  A link with the two related ETSI NFV use cases
   (Virtualisation of Mobile Core Network and IMS, and Virtualisation of
   Mobile base station) will be included.

   The EPS architecture and some of its standardized interfaces are
   depicted in Figure 7.  The EPS provides IP connectivity to user
   equipment (UE) (i.e., mobile nodes) and access to operator services,
   such as global Internet access and voice communications.  The EPS
   comprises the core network -- called Evolved Packet Core (EPC) -- and
   different radio access networks: the 3GPP Access Network (AN), the
   Untrusted non-3GPP AN and the Trusted non-3GPP AN.  There are
   different types of 3GPP ANs, with the evolved UMTS Terrestrial Radio
   Access Network (E-UTRAN) as the most advanced one.  QoS is supported
   through an EPS bearer concept, providing bindings to resource
   reservation within the network.

   The evolved NodeB (eNB), the Long Term Evolution (LTE) base station,
   is part of the access network that provides radio resource
   management, header compression, security and connectivity to the core
   network through the S1 interface.  In an LTE network, the control
   plane signaling traffic and the data traffic ar handled separately.
   The eNBs transmit the control traffic and data traffic separately via
   two logically separate interfaces.

   The Home Subscriber Server, HSS, is a database that contains user
   subscriptions and QoS profiles.  The Mobility Management Entity, MME,
   is responsible for mobility management, user authentication, bearer
   establishment and modification and maintenance of the UE context.

   The Serving gateway, S-GW, is the mobility anchor and manages the
   user plane data tunnels during the inter-eNB handovers.  It tunnels
   all user data packets and buffers downlink IP packets destined for
   UEs that happen to be in idle mode.

   The Packet Data Network (PDN) Gateway, P-GW, is responsible for IP
   address allocation to the UE and is a tunnel endpoint for user and
   control plane protocols.  It is also responsible for charging, packet




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   filtering, and policy-based control of flows.  It interconnects the
   mobile network to external IP networks, e.g. the Internet.

   In this architecture, data packets are not sent directly on an IP
   network between the eNB and the gateways.  Instead, every packet is
   tunneled over a tunneling protocol - the GPRS Tunneling Protocol (GTP
   over UDP/IP.  A GTP path is identified in each node with the IP
   address and a UDP port number on the eNB/gateways.  The GTP protocol
   carries both the data traffic (GTP-U tunnels) and the control traffic
   (GTP-C tunnels).  Alternatively Proxy Mobile IP (PMIPv6) is used on
   the S5 interface between S-GW and P-GW.

   In addition to the above basic functions and entities, there are also
   additional features being discussed by the 3GPP that are relevant
   from a network virtualization viewpoint.  One example is the Traffic
   Detection Function (TDF), which can be used by the P-GW, and in
   general by the whole transport network, to decide how to forward the
   traffic.  In a virtualized infrastructure, this kinf of information
   can be used to elastic and dynamically adapt the network capabilities
   to the traffic nature and volume.































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            +---------------------------------------------------------+
            |                           PCRF                          |
            +-----------+--------------------------+----------------+-+
                        |                          |                |
   +----+   +-----------+------------+    +--------+-----------+  +-+-+
   |    |   |          +-+           |    |  Core Network      |  |   |
   |    |   | +------+ |S|__         |    | +--------+  +---+  |  |   |
   |    |   | |GERAN/|_|G|  \        |    | |  HSS   |  |   |  |  |   |
   |    +-----+ UTRAN| |S|   \       |    | +---+----+  |   |  |  | E |
   |    |   | +------+ |N|  +-+-+    |    |     |       |   |  |  | x |
   |    |   |          +-+ /|MME|    |    | +---+----+  |   |  |  | t |
   |    |   | +---------+ / +---+    |    | |  3GPP  |  |   |  |  | e |
   |    +-----+ E-UTRAN |/           |    | |  AAA   |  |   |  |  | r |
   |    |   | +---------+\           |    | | SERVER |  |   |  |  | n |
   |    |   |             \ +---+    |    | +--------+  |   |  |  | a |
   |    |   |   3GPP AN    \|SGW+----- S5---------------+ P |  |  | l |
   |    |   |               +---+    |    |             | G |  |  |   |
   |    |   +------------------------+    |             | W |  |  | I |
   | UE |                                 |             |   |  |  | P |
   |    |   +------------------------+    |             |   +-----+   |
   |    |   |+-------------+ +------+|    |             |   |  |  | n |
   |    |   || Untrusted   +-+ ePDG +-S2b---------------+   |  |  | e |
   |    +---+| non-3GPP AN | +------+|    |             |   |  |  | t |
   |    |   |+-------------+         |    |             |   |  |  | w |
   |    |   +------------------------+    |             |   |  |  | o |
   |    |                                 |             |   |  |  | r |
   |    |   +------------------------+    |             |   |  |  | k |
   |    +---+  Trusted non-3GPP AN   +-S2a--------------+   |  |  | s |
   |    |   +------------------------+    |             |   |  |  |   |
   |    |                                 |             +-+-+  |  |   |
   |    +--------------------------S2c--------------------|    |  |   |
   |    |                                 |                    |  |   |
   +----+                                 +--------------------+  +---+

             Figure 7: EPS (non-roaming) architecture overview

A.2.  Virtualizing the 3GPP EPS

   TBD.  We describe how a "virtual EPS" (vEPS) would look like and the
   existing gaps that exist from the point of view of network
   virtualization.

Authors' Addresses








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   Carlos J. Bernardos
   Universidad Carlos III de Madrid
   Av. Universidad, 30
   Leganes, Madrid  28911
   Spain

   Phone: +34 91624 6236
   Email: cjbc@it.uc3m.es
   URI:   http://www.it.uc3m.es/cjbc/


   Akbar Rahman
   InterDigital Communications, LLC
   1000 Sherbrooke Street West, 10th floor
   Montreal, Quebec  H3A 3G4
   Canada

   Email: Akbar.Rahman@InterDigital.com
   URI:   http://www.InterDigital.com/


   Juan Carlos Zuniga
   InterDigital Communications, LLC
   1000 Sherbrooke Street West, 10th floor
   Montreal, Quebec  H3A 3G4
   Canada

   Email: JuanCarlos.Zuniga@InterDigital.com
   URI:   http://www.InterDigital.com/


   Luis M. Contreras
   Telefonica I+D
   Ronda de la Comunicacion, S/N
   Madrid  28050
   Spain

   Email: luismiguel.conterasmurillo@telefonica.com


   Pedro Aranda
   Telefonica I+D
   Ronda de la Comunicacion, S/N
   Madrid  28050
   Spain

   Email: pedroa.aranda@telefonica.com




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