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Network Working Group                                            M. Chen
Internet-Draft                                                M. McBride
Intended status: Informational              Huawei Technologies Co., Ltd
Expires: July 20, 2013                                             L. Ou
                                                           China Telecom
                                                        January 16, 2013


Software Defined Networks Use Case for Virtual Connection and Network on
                                 Demand
                draft-mm-sdn-vc-vn-on-demand-use-case-02

Abstract

   Software Defined Networks (SDN) provide a way to virtualize and
   abstract the network and presents the virtual/abstract resources to
   the third-party applications/software.  The applications/software
   can, by the programmable interface or Northbound API, request,
   manipulate and monitor the services that the network provided.  With
   this SDN capability, more innovative services can be introduced and
   rapidly deployed.  Additionally, existing services can be deployed
   and managed in a much more simple way.

   This document outlines two use cases that leverage the SDN
   architecture/model to implement a kind of "self-help" and automated
   set of network services: Virtual Connection on Demand (VCoD) and
   Virtual Network on Demand (VNoD).

Requirements Language

   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 RFC 2119 [RFC2119].

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
   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
   material or to cite them other than as "work in progress."



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   This Internet-Draft will expire on July 20, 2013.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 4
   2.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
     2.1.  Reference Architecture  . . . . . . . . . . . . . . . . . . 5
     2.2.  VC on Demand  . . . . . . . . . . . . . . . . . . . . . . . 6
     2.3.  VN on Demand  . . . . . . . . . . . . . . . . . . . . . . . 7
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 9
   4.  Security Considerations . . . . . . . . . . . . . . . . . . . . 9
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 9
   6.  Normative References  . . . . . . . . . . . . . . . . . . . . . 9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 9







































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1.  Introduction

   At present, applications and networks are independent of each other,
   and there is almost no interaction between the two layers.  The
   applications normally have no idea about how the application data be
   transmitted over the network nor the status of the network.  The
   application requirements and constraints to the network are passed to
   service providers by some bill forms or contracts, and then the
   network operators set up the network according to the bill forms or
   contracts.  These processes will take a considerably long time to
   take effect and are error-prone.  If there are some new requirements
   and updates, the processes will be re-done.  This network service
   architecture and model is increasingly unable to meet the needs of
   modern applications (e.g., Cloud service, Data Center, etc.), which
   may frequently request to create/delete network connections, adjust
   the existing paths or choose the desired paths per performance
   characteristic (e.g., delay, loss, jitter, etc.), price or some other
   conditions.  So, a new network service architecture and model is
   required, and Software Defined Networks (SDNs) are considered to be a
   set of promising solutions, which opens the network and provides
   programmable interface (e.g., Northbound API) to the applications and
   third-party software.

   There are several kinds of network services: transport service
   (Optical, Ethernet, Internet Protocol (IP), Multiprotocol Label
   Switching (MPLS) Traffic Engineering (TE ) Label Switched Path (LSP),
   etc.), Virtual Private Network (VPN ) service(VLAN, VxLAN, L2/L3 VPN,
   etc.), policy related service (e.g., Access Control List (ACL)),
   security service, etc.  This document mainly focuses on the transport
   and VPN related services that can be abstracted and categorized into
   two types: Virtual Connection (VC) and Virtual Network(VN) services.
   Other services are basically dependent on these two services.  For
   example, when you want to configure an ACL, load balance or security
   service, you must configure it on a specific connection or network.
   That is, they are the subordinate services of the connection and
   network services.  The VC or VN is a kind of logical/abstract network
   services, where the VC can be mapped to a flow (as defined in
   Openflow), an optical path(a lambda, fiber, etc.), an E-line, a
   Pseudo Wire (PW), a TE LSP etc., and the VN can be mapped to a VLAN,
   a VxLAN, an L2/L3 VPN, etc.  With the VC and VN concept, it could
   present a set of uniform abstract services and interfaces to the
   applications, independent of the underlying network diversity and
   complexity.

   This document describes the use cases which leverage the SDN
   architecture and model to implement the Virtual Connection on Demand
   (VCoD) and Virtual Network on Demand (VNoD) services.




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2.  Use Cases

2.1.  Reference Architecture

                              +-------------+
                              | Application |
                              +-------------+
  ...................................|..................................
         +-------------+  +-------------+   +-------------+
         | Controller1 |  | Controller2 |   | Controller3 |
         +-------------+  +-------------+   +-------------+
  .............|................|..................|.............
         +------------+   +------------+     +-------------+
   Site1-|VDE         |   |            |+    |          VDE|--Site3
         |   \ ...-VDB|---|VDB  ... VDB|++---|VDB- ... /   |
         |   /        |   |            |||   |         \   |
   Site2-|VDE         |   |            |||   |          VDE|--Site4
         +-----VD1----+   +-++--VD2----+||   +-----VD3-----+
                            ++---VDx----+|
                             +----VDy----+

   VD - Virtual Domain
   VDE - Virtual Domain Edge
   VDB - Virtual Domain Boundary

                          Figure 1 SDN Reference Architecture

   Figure 1 is a SDN reference architecture that consists of 3 tiers,
   application, controller and the physical network.  For a large scale
   network, there normally should be multiple controllers and each of
   them is responsible for a specific domain of the network.  Here, we
   introduce a concept of Virtual Domain (VD) that provides a way to
   abstract and split the physical network into controllable domains,
   where each domain has its own controller.  Each VD has its own
   Virtual Domain Edges (VDE) that are the service access points for the
   VD, and the Virtual Domain Boundaries (VDB) are the boundaries
   between VDs.

   There are many ways to split and plan the domains, for example, it
   could simply be based on the natural routing domains(e.g., per an
   area or AS) to split and form the VD .  And it also could be based on
   the service to split the domain, meaning the same physical network
   could be abstracted to different VDs and each providing different
   services; e.g., an IP/MPLS metro network could be abstracted to an L2
   VPN VD and an L3 VPN VD simultaneously.






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2.2.  VC on Demand

                     +---------+       +----------------------+
                     |   APP   |<----->| SDN Discovery Server |
                     +----+----+       +----------------------+
     +--------+           |
     | Policy |\          |
     +--------+ \+--------+------+     +---------------+
     +--------+ /| VC Controller | ... | VC Controller |
     |  PCE   |/ +------------+--+     +---------------+
     +--------+               |
                            --+--------------------
                    ////////                       \\\\\\\\
               |////                                       \\\\|
              |                                                 |
             |VDE1===========================================VDE2|
              |                                                 |
               |\\\\          Physical Network             ////|
                    \\\\\\\\                       ////////
                            -----------------------

                            Figure 2 VC on Demand

   Figure 2 illustrates the flow, involved with requesting a new Virtual
   Connection, which includes the following steps:

   1.  Service Discovery

   First, the application needs to discover the VC controller and its
   capabilities and services.  Typically , there will be multiple
   controllers.  The locations, capabilities, and supplied services of
   the controllers may change over time.  The SDN discovery server could
   present a relevant fixed access location to the application and in
   order to help make the model more robust.

   The application sends a query message to the SDN discovery Server
   (similar to ALTO server discovery) to retrieve the candidate
   controllers and their relevant locations, capabilities, services,
   etc.  The App needs to determine which controller is the correct one
   to use.

   2.  VC Request/Response

   When the controller is determined, the application sends a VC request
   to the VC Controller to Create/Delete/Modify/Query a VC (e.g.,
   request a new VC from VDE1 to VDE2).  The VC controller could choose
   to respond to the application immediately, or wait for the VC to be
   successfully constructed and then respond to the application.



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   3.  VC Path Compute

   According to the requirements and constraints (e.g., bandwidth,
   delay, loss etc.) from the App, the VC controller needs to determine
   a specific network service to serve the VC request, map the VC to a
   specific network path (e.g., mapping the VC to an openflow-based
   flow/an E-line/an E-tree/a PW/a TE LSP... ) and then compute/find the
   path.  VC controller could finish the path computation by itself (for
   example, the controller has an embedded path computation engine), or
   it may send a path compute request to another entity(e.g., Path
   Computation Element (PCE)) to finish the path computation.

   4.  VC Provisioning

   When the VC path is determined, the VC controller will then send VC
   provisioning request to the related network devices to provision the
   path.  For example, the request could be to install an entry in the
   openflow table, or trigger the ingress PE to signal a TE LSP or PW,
   etc.  The communication channel between VC controller and the network
   devices could be either the existing protocols (e.g., Openflow,
   Netconf, Command Line Interface(CLI), etc.) or new APIs defined in
   the future.

   5.  VC Monitoring

   Once a VC is established, the application may require the ability to
   monitor the status of the VC.  The application data could be
   directed, according to the VC status, to switchover the data to a
   backup path when the master path is broken, or to switchover the data
   to a more cost-effective path, etc.

   6.  VC Policy

   TBD

2.3.  VN on Demand















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                     +--------+       +----------------------+
                     |  APP   |<----->|  SDN Discovery Server|
                     +----+---+       +----------------------+
                          |
     +--------+  +--------+------+     +---------------+
     | Policy |--| VN Controller | ... | VN Controller |
     +--------+  +------------+--+     +---------------+
                              |
                            --+--------------------
                    ////////  VDE3                \\\\\\\\
               |////                                      \\\\|
              |                                                |
             |VDE1                                          VDE2|
              |              Physical Network                  |
               |\\\\                                      ////|
                    \\\\\\\\                 VDE4 ////////
                            -----------------------

                            Figure 3 VN on Demand

   Figure 3 illustrates the flow, involved with requesting a new Virtual
   Network:

   1.  Service Discovery

   Similar to VC on Demand, the application first needs to find where
   the VN controller is located and the capabilities and services that
   the controller can provide.  Then it can be determined who the proper
   controller is according to response from the SDN discovery server.

   2.  VN Request/Response

   Once the controller is determined, the application sends a VN request
   to the VN Controller to Create/Delete/Modify/Query a VN.  The VN
   controller could choose to respond to the application immediately, or
   wait for the VN to be successfully constructed and then respond to
   the application.

   3.  VN Orchestration

   According to the requirements and constraints from the application,
   the VN controller needs to determine a specific network service to
   serve the VN request, map the VN to one or several specific physical
   or logical networks (e.g., mapping the VN to a VLAN/VxLAN/L2VPN/
   L3VPN, or a combination of them) and then finish the VN computation/
   orchestration.

   4.  VN Provisioning



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   When the VN orchestration is completed, the VN controller will then
   send a VN provisioning request to the related network devices to
   provision the VN.

   5.  VN Monitoring

   Once a VN is constructed, the application may require the ability to
   monitor the status of the VN where it could steer the application
   data according to the VN status.

   6.  VN Policy

   TBD


3.  IANA Considerations

   This document makes no request of IANA.

   Note to RFC Editor: this section may be removed on publication as an
   RFC.


4.  Security Considerations

   TBD


5.  Acknowledgements


6.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.


Authors' Addresses

   Mach(Guoyi) Chen
   Huawei Technologies Co., Ltd
   No. 3 Xinxi Road, Shang-di, Hai-dian District
   Beijing  100085
   China

   Email: mach@huawei.com





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   Mike McBride
   Huawei Technologies Co., Ltd
   2330 Central Expressway
   Santa Clara, CA  95050
   USA

   Email: michael.mcbride@huawei.com


   Liang Ou
   China Telecom


   Email: oul@gsta.com





































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