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Versions: 00 01                                                         
SDNRG                                                         R. Gu, Ed.
Internet-Draft                                                     C. Li
Intended status: Informational                                   R. Wang
Expires: September 1, 2016                                  China Mobile
                                                       February 29, 2016


  Problem statement of SDN and NFV co-deployment in cloud datacenters
          draft-gu-sdnrg-problem-statement-of-sdn-nfv-in-dc-01

Abstract

   With the development of cloud computing technology, cloud datacenters
   have been influenced.  Co-deployment of SDN and NFV technology shows
   its distinct advantages of vitalizing network resources in providing
   VPC services and SFC services.In order to deploy SDN and NFV in cloud
   datacenters, a resolution test has been conducted.  According to the
   resolution test, SDN and NFV technology has been nearly mature for
   the commercial deployment in operators' network.  However, there are
   some key problems on network architecture, virtualized platform,
   standard interfaces, performance of SDN devices and so on to be
   working out in practical practice.

Status of This Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
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   This Internet-Draft will expire on September 1, 2016.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of



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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Definition of terms . . . . . . . . . . . . . . . . . . . . .   3
   4.  SDN and NFV usecase in cloud datacenters  . . . . . . . . . .   3
   5.  Resolution test of SDN and NFV in cloud datacenters . . . . .   8
   6.  Problems and aspects to be considered in the trail deployment   9
   7.  Conclusion  . . . . . . . . . . . . . . . . . . . . . . . . .  11
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   10. Normative References  . . . . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   Datacenters have been heavily impacted due to the development and
   large-scale deployment of cloud computing technology.  Co-deployment
   of SDN and NFV technology shows its distinct advantages of
   virtualizing network resources in the scenario of cloud datacenter
   such as convenient and elastic.

   SDN technology helps the cloud datacenters with central-management
   and resource efficiency.  NFV brings up virtual machines instead of
   physical firewall, load balancer, and VPN gateway devices.  Thus VPC
   services and service functions are provided with the SDN
   architecture, NFV elements, standard interfaces and the designing
   flow table.

   In order to deploy SDN and NFV in cloud datacenters, we have
   conducted a resolution test aiming at co-deployment of SDN and NFV.
   According to the resolution test, SDN and NFV technology have been
   nearly mature for the commercial deployment in operators' network.
   However, there are some key problems on network architecture,
   virtualized platform, standard interfaces and so on to be working out
   in practical practice.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].





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3.  Definition of terms

   NAT: network address translation

   NFV: network function virtualization

   SDN: software defined network

   SF: service function

   SFC: service function chaining

   VAS: value-added service

   VFW: virtual firewall

   VLB: virtual load balancer

   VM: virtual machine

   VPC: virtual private cloud

   DCI: datacenter interconnect

4.  SDN and NFV usecase in cloud datacenters

   In cloud datacenters, the SDN and NFV architecture includes the
   applications to tenants, SDN controller, network function virtualized
   manager (NFVM), SFC controller and the service function node.  With
   the orchestration, the SDN controller, SFC controller and the NFV
   manager work in coordination to provide the auto-deployed services
   such as VPC, VAS of layer 4 - layer 7 and so on.

   Tenants make the requirement of services in the service applications.
   Service application records tenants' network and service requirements
   and translates them into the SDN controller, SFC controller and the
   NFV managers with the logical network mapping to the physical
   network.  The orchestrator including the virtualized platform is in
   charge of the orchestration and management of NFV infrastructure and
   software resources, and realizing network services.  The SDN
   controller is a logically centralized entity with a general view of
   the network and in charge of SDN data paths, while the SFC controller
   is in central control of the service function chain according to the
   requirements from the service applications.  The NFV manager is
   responsible for NFV lifecycle management such as installation,
   update, query, scaling and termination.  In the bottom, network
   elements are the resource instances which can be a virtual instance
   such as a virtual machine or be embedded in a physical network



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   element such as the virtual load balance instances or the physical
   firewall located in the resource pool.

   In fact, there are virtual machines and baremetal servers in cloud
   datacenters.  So there are serveral scenarios including virtual
   machines only, bare-mental servers only and virtual machines and
   baremental server co-existed.

   A newly-built cloud datacenter based on SDN and NFV is shown in
   scenario A.  In this scenario, network elements are virtulized
   including virtual switch, virtual machines, virtual routers, virtual
   load balancer,and virtual firewall.In this scenario, all the network
   elements are virtualized for the advantages of elasticity.






































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    --------------------------
    |                        |
    |  Service Application   +---------------------------
    |                        |                          |
    ----+--------------+------                          |
        |              |                                |
        |              |                                |
        |     ---------+-------                         |
        |     |               |                         |
        |     | Orchestrator  +----------------------   |
        |     | (Openstack)   |                     |   |
        |     ----+---------+--                     |   |
        |         |         |                       |   |
        |         |         |                       |   |
     ---+---------+----   --+---------------   -----+---+------
     |                |   |                |   |              |
     | SDN Controller |   | SFC Controller |   |  NFV manager |
     |                |   |                |   |              |
     ---+--------------   ---------+--------   --------+-------
        |                          |                   |
   -----+--------------------------+-------------------+-------
   |                                                          |
   |                    -----   -----   -----    ------       |
   |                    |VSW|   |VSW|   |VSW|    | VR |       |
   |                    -----   -----   -----    ------       |
   |                                                          |
   |         ------       ------      ------     ------       |
   |         | VM |       | VM |      | VLB|     | VFW|       |
   |         ------       ------      ------     ------       |
   |                                                          |
   |   network element                                        |
   ------------------------------------------------------------


         Figure 1: Scenario A of SDN and NFV in cloud datacenters

   Scenario B shows SDN architecture of physical network elements such
   as bare-metal servers, physical load balancer, and physical firewall.
   Actually, virtual machines can not meet the requirement of some
   service systems.  Thus bare-metal servers exist in the architecture.
   In this scenario, SDN ToR switch is deployed on the top of the bare-
   metal server acting as the vtep.By the way, some model of
   orchestrator is responsible for the management of bare-metal server,
   ironic model in openstack as an example.







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    --------------------------
    |                        |
    |  Service Application   +---------------------------
    |                        |                          |
    ----+--------------+------                          |
        |              |                                |
        |              |                                |
        |     ---------+-------                         |
        |     |               |                         |
        |     | Orchestrator  +----------------------   |
        |     |  (Openstack)  |                     |   |
        |     ----+---------+--                     |   |
        |         |         |                       |   |
        |         |         |                       |   |
     ---+---------+----   --+---------------   -----+---+------
     |                |   |                |   |              |
     | SDN Controller |   | SFC Controller |   |  NFV manager |
     |                |   |                |   |              |
     ---+--------------   ---------+--------   --------+-------
        |                          |                   |
   -----+--------------------------+-------------------+-------
   |                                                          |
   |     -------            -------                ------     |
   |     | ToR |            | ToR |                | LB |     |
   |     ---+---            ---+---                ------     |
   |        |                  |                              |
   | -------+------     -------+------             ------     |
   | | bare-mental|     | bare-mental|             | FW |     |
   | |   server   |     |   server   |             ------     |
   | --------------     --------------                        |
   |                                                          |
   | network element                                          |
   ------------------------------------------------------------


         Figure 2: Scenario B of SDN and NFV in cloud datacenters

   Scenario C and scenario D is the combination of scenario A and
   scenario B.  In scenario C, bare-metal servers remain while virtual
   load balancer and virtual firewall are adopeted.  In scenario D, both
   bare-metal servers and virtual machines exist with virtual load
   balancer and virtual firewall adopeted.









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    --------------------------
    |                        |
    |  Service Application   +---------------------------
    |                        |                          |
    ----+--------------+------                          |
        |              |                                |
        |              |                                |
        |     ---------+-------                         |
        |     |               |                         |
        |     | Orchestrator  +----------------------   |
        |     |  (Openstack)  |                     |   |
        |     ----+---------+--                     |   |
        |         |         |                       |   |
        |         |         |                       |   |
     ---+---------+----   --+---------------   -----+---+------
     |                |   |                |   |              |
     | SDN Controller |   | SFC Controller |   |  NFV manager |
     |                |   |                |   |              |
     ---+--------------   ---------+--------   --------+-------
        |                          |                   |
   -----+--------------------------+-------------------+-------
   |                                                          |
   |     -------            -------             -------       |
   |     | ToR |            | ToR |             | VLB |       |
   |     ---+---            ---+---             -------       |
   |        |                  |                              |
   | -------+------     -------+------                        |
   | | bare-mental|     | bare-mental|          -------       |
   | |   server   |     |   server   |          | VFW |       |
   | --------------     --------------          -------       |
   |                                                          |
   | network element                                          |
   ------------------------------------------------------------


         Figure 3: Scenario C of SDN and NFV in cloud datacenters















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 --------------------------
 |                        |
 |  Service Application   +---------------------------
 |                        |                          |
 ----+--------------+------                          |
     |              |                                |
     |              |                                |
     |     ---------+-------                         |
     |     |               |                         |
     |     | Orchestrator  +----------------------   |
     |     |  (Openstack)  |                     |   |
     |     ----+---------+--                     |   |
     |         |         |                       |   |
     |         |         |                       |   |
  ---+---------+----   --+---------------   -----+---+------
  |                |   |                |   |              |
  | SDN Controller |   | SFC Controller |   |  NFV manager |
  |                |   |                |   |              |
  ---+--------------   ---------+--------   --------+-------
     |                          |                   |
-----+--------------------------+-------------------+-------
|                                                          |
|     -------            -------             ------        |
|     | ToR |            | VSW |             | VR |        |
|     ---+---            -------             ------        |
|        |                                                 |
| -------+------         -------    -------   -------      |
| | bare-mental|         | VM  |    | VLB |   | VFW |      |
| |   server   |         -------    -------   -------      |
| --------------                                           |
| network element                                          |                                                    |
------------------------------------------------------------


         Figure 4: Scenario D of SDN and NFV in cloud datacenters

5.  Resolution test of SDN and NFV in cloud datacenters

   The resolution test is based on the architecture introduced with the
   KVM virtualized platform, and Openstack as the orchestrator.  In the
   resolution test, the whole systems, network architecture, SDN
   controller, and forwarding devices are tested of functions,
   performances and security under normal and stress conditions.








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6.  Problems and aspects to be considered in the trail deployment

   It's found out that some key problems exist when introducing SDN and
   NFV technology into cloud datacenters under the resolution tests and
   the practical trail.  Problems rely on aspects such as virtualized
   platforms, network architectures, interface standardization, and some
   others listed as follows.

   (1)Virtualized platforms

   KVM virtualized platform is adopted in our test.  However, serveral
   other virtualized platforms are used in the recent network such as
   VMWARE ESXI and Xen, which may be not well supported by Openstack.
   The main reason relies on that Openstack is an open-source cloud
   operating system developing based on KVM platform, which is widely
   used in public cloud datacenters.  Actually in the private cloud
   datacenters, other virtualized platforms such as VMware and XEN are
   widely adopted.  Thus more work needs to be focused on other
   virtualized platforms carrying on SDN technology with platforms of
   much more open interfaces and more interface docking attempts.

   (2) Network architecture

   The network architecture of SDN is clear according to other
   standardization organizations with hierarchical layers of application
   layer, orchestrator, controlling layer and forwarding layer.  When
   adding the virtualized network elements into the SDN architecture,
   problems arise around the network architecture of SDN and NFV co-
   deployed in the cloud datacenters.  How can the orchestration layer,
   SDN controller, SFC controller, NFV manager co-operate in order to
   provide the VPC services and SFC services.  What's the relationship
   and specific role-taking between the service application,
   orchestration layer, SDN controller, SFC controller and NFV manager.
   The specific interfaces between these related parts are obscure as
   well.

   In scenario D, virtual machines and baremetal servers exist in the
   network and baremetal servers should be managed by openstack as well
   as virtual machines.Even through the ironic module of openstack can
   support baremetal servers, questions arise on aspects such as
   openstack Kilo is needed,additional network partition including IPMI,
   PXE and service network,SDN switches should be deployed additionally
   and so on.

   (3) Interface standardization

   Due to the incomplete interface of Openstack, interface
   standardization should be taking into consideration.  Nowadays,



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   physical servers can be managed by Openstack through ironic module
   while without widely attempts.  Besides, the FW plug-in is limited
   into only one vendor rather than LB.  Service function chaining
   interfaces are still under discussion without being published with
   SFC protocols under discussion.  The specific interfaces between SDN
   controller, SFC controller and NFV manager are obscure as well.
   Above all, the interface standardizations should be kept researching
   on.

   (4) Virtualization high availability

   As virtual machines and virtualized platforms are brought in,
   reliability can be a problem.  Reliability can be divided into
   several layers: the virtual network elements, Openstack, controller,
   virtual link and so on.  High availability of virtual network
   elements integrated in the SDN architectures are without
   standardization.

   (5) Benchmark standardization

   In the resolution test, it works out that the benchmark
   standardization should be focused on.  In actual test, both
   encapsulation technology of VxLAN and MPLSoGRE exist in the SDN
   overlay resolution with difficult comparison.  Besides, there are two
   realization mechanisms of active and passive trigger mode when SDN
   controller communicates with the forwarding devices.  Thus the
   benchmark of SDN controller performance runs to a problem.

   (6) extension of network

   The numbers of virtual machines and baremetal servers are limited by
   SDN controller, the performance of SDN forwarding devices and
   openstack.  In order to extend the SDN network, SDN devices and
   openstack should interact with each other.  Extensible solutions
   should be researched on.

   (6) DCI

   According to the development of SDN network, it's more complicated to
   realize the datacenter interconnect, for the reason that SDN
   datacenter and tradional datacenter coexist.  The interconnections of
   SDN datacenters benefit from SDN gateway, while interconnections
   between SDN datacenter and traditional datacenter should be focused
   on with SDN devices added in the traditional datacenters and more
   details to be discussed.

   (7) Practical practice experience




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   The technology of NFV and SDN is still in the trial stage which is l\
   qack of practical practice experience.  According to the scenarios,
   NFV elements can be deployed behind the gateway or in rtyukNAT
   devices are alternated.  The deployment guidance of practical
   practice is eager.  to be shared.

7.  Conclusion

   SDN and NFV technology has been planned to be co-deployed in the
   cloud datacenters in providing services such as VPC and VAS of
   layer4-layer7.Through the resolution test, we have found out that key
   problems on network architecture, virtualized platform, standard
   interfaces, high availability, practice guidance and many others
   exist.More tests, trails and standardization work need to be
   conducted in preparing the large-scale commercial deployment of SDN
   and NFV technology in cloud datacenters.

8.  Security Considerations

   None.

9.  IANA Considerations

   None.

10.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC2234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", RFC 2234, DOI 10.17487/RFC2234,
              November 1997, <http://www.rfc-editor.org/info/rfc2234>.

Authors' Addresses

   Rong Gu (editor)
   China Mobile
   32 Xuanwumen West Ave, Xicheng District
   Beijing  100053
   China

   Email: gurong_cmcc@outlook.com






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   Chen Li
   China Mobile
   32 Xuanwumen West Ave, Xicheng District
   Beijing  100053
   China

   Email: lichenyj@chinamobile.com


   Ruixue Wang
   China Mobile
   32 Xuanwumen West Ave, Xicheng District
   Beijing  100053
   China





































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