CCAMP Working Group                                               S. Liu
Internet-Draft                                              China Mobile
Intended status: Standards Track                                H. Zheng
Expires: 8 September 2022                            Huawei Technologies
                                                                  A. Guo
                                                  Futurewei Technologies
                                                                 Y. Zhao
                                                            China Mobile
                                                            7 March 2022


   Problem Statement and Requirements of Accessing Cloud via Optical
                                Network
           draft-liu-ccamp-optical2cloud-problem-statement-00

Abstract

   This document describes the problem statement and requirements for
   accessing cloud via optical network.  The supported scenarios include
   the multi-cloud access, optical leased line and cloud VR.

Status of This Memo

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

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   This Internet-Draft will expire on 8 September 2022.

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   extracted from this document must include Revised BSD License text as
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Multi-cloud access  . . . . . . . . . . . . . . . . . . .   3
     2.2.  High-quality leased line  . . . . . . . . . . . . . . . .   5
     2.3.  Cloud virtual reality (VR)  . . . . . . . . . . . . . . .   5
   3.  Requirement and problem Statement . . . . . . . . . . . . . .   6
     3.1.  LxVPN over optical networks for multiple-to-multiple
           access  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     3.2.  Service-awareness . . . . . . . . . . . . . . . . . . . .   6
     3.3.  Deterministic performance . . . . . . . . . . . . . . . .   6
     3.4.  High performance and high reliability . . . . . . . . . .   7
   4.  Manageability Considerations  . . . . . . . . . . . . . . . .   7
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Cloud-related applications are becoming popular and widely deployed
   in enterprises and vertical industries.  Companies with multiple
   campuses are interconnected together with the remote cloud for
   storage and computing.  Such cloud services require high quality
   experiences including high availability, low latency, on- demand
   bandwidth adjustments and so on.

   Optical network is playing an increasingly important role for bearing
   cloud traffic due to its large bandwidth and low latency.  With the
   TDM switching technology, there is no need for queuing and scheduling
   in optical networks as opposed to IP-based networks, which can
   drastically improve the users experience on service quality.

   Optical network using OTN (Optical Transport Network) or wavelength-
   switching provides TDM-based connections with an access bandwidth
   granularity of 1.25Gbps, i.e. ODU0 (Optical Data Unit) and above,
   which is usually more than the demand for normal user, and user
   traffic are usually aggregated before they are carried into the
   network.  However, recent development in ITU-T work items have aimed



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   to enable OTN to support small-granularity services of 2Mbps-1Gbps
   through the introduction of Optical Service Unit (OSU).  This
   potentially allows L2/L3 services to be carried directly over optical
   networks and transport end to end, making it even a more suitable
   solution for bearing cloud network traffic.

   [I-D.ietf-rtgwg-net2cloud-problem-statement] and
   [I-D.ietf-rtgwg-net2cloud-gap-analysis] gave a detailed description
   on the coordination requirements between the network and the cloud
   assuming the network is IP-based.  This document complements the
   analysis by further examining the requirements from an optical
   network perspective.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  Scenarios

   With the prevalence of cloud services, enterprises services, home
   services such as AR/VR, accessing clouds with optical networks is
   increasingly attractive and becoming an option for the users.
   Following scenarios provide a few typical applications.

2.1.  Multi-cloud access

   Cloud services are usually supported by multiple interconnected data
   centers (DCs).  Besides the on-demand, scalable, high available and
   uses-based billing, mentioned in
   [I-D.ietf-rtgwg-net2cloud-problem-statement], there are also needs
   for Data Centre Interconnect (DCI) about high requirements on
   capacity, latency, and flexible scheduling.  This use case requires
   specific capabilities of advanced OTN for DCIs.














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      //------\\                                               /----\
    ||Enterprise|\\                                          |Vertical|
    ||   CPE    || \\        ------------          +-----+   /|Cloud |
      \\------//     \ +---*/            \*---+    |Cloud| //  \----/
                       |O-A|              |O-E|----+ GW  |/
                       +---+              +---+    +-----+
                      |      OTN Networks      |
      //-----\\       ++---+              +---+    +-----+     /-----\
    || Vertical||-----+ O-A|              |O-E|----+Cloud|---||Private||
     |   CPE   |      +----*\            /*---+    | GW  |    | Cloud |
      \\-----//              ------------          +-----+     \-----/

          Figure 1: Cloud Accessing through Optical Network

   A data center is a physical facility consisting of multiple bays of
   interconnected servers, that performs computing, storage, and
   communication needed for cloud services.  Infrastructure-as-a-service
   may be deployed in both public and private clouds, where virtual
   servers and other virtual resources are made available to users on
   demand and by self-service.

   One typical scenario is the intra-city DCs, which communicate with
   each other via the intra-city DCI network to meet the high
   availability requirements.  The active-active and Virtual Machine
   (VM) migration services which require low latency are provided by the
   intra-city DCI network.  The intra-city DCI network supports the
   public and/or the private cloud services, such as video, games,
   desktop cloud, and cloud Internet cafe services.  To ensure low
   latency, intra-city DCI network is deployed in the same city or
   adjacent cities.  The distance is typically less than 100 km and more
   likely less than 50km.  One city may have several large DCs.

   DCs are ideally interconnected through Layer 2/3 switches or routers
   with full mesh connectivity.  However, to improve interaction
   efficiency as well as service experience, OTN is also evaluated as an
   option to be used for DC interconnection.

   There are three kinds of the connection relationship, point to point
   access, single to multiple point access, and multiple to multiple
   point access.  Different types of connections are referring different
   shapes, single point accessing single cloud, single point accessing
   multiple clouds and multiple points accessing multiple clouds.









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2.2.  High-quality leased line

   The high-quality private line provides high security and reliability
   and is suitable to ensure the end-to-end user experience for large
   enterprises such as financial, medical centers and education
   customers.  The main advantages and drivers of the high quality
   private line are as follows.

   *  High quality private lines provide large bandwidth, low latency,
      secure and reliable for any type of connection.

   *  Accelerate the deployment of cloud services.  The high quality and
      high security of the private line connecting to the cloud can
      enable enterprises to move more core assets to the cloud and use
      low-latency services on the cloud.  Cloud-based deployment helps
      enterprises reduce heavy asset allocation and improve energy
      saving, so that enterprises can focus on their major business.

   *  Reduce operator's CAPEX and OPEX.  The end-to-end service
      provisioning system enables quick provisioning of private line
      services and improves user experience.  Fault management can be
      done from the device level to reduce the complexity of location.

   *  Enable operators to develop value-added services by providing
      enterprise users with latency maps, availability maps,
      comprehensive SLA reports, customized latency levels, and dynamic
      bandwidth adjustment packages.

2.3.  Cloud virtual reality (VR)

   Cloud VR offloads computing and cloud rendering in VR services from
   local dedicated hardware to a shared cloud infrastructure.  Cloud
   rendered video and audio outputs are encoded, compressed, and
   transmitted to user terminals through fast and stable networks.  In
   contrast to current VR services, where good user experience primarily
   relies on the end user purchasing expensive high-end PCs for local
   rendering, cloud VR promotes the popularization of VR services by
   allowing users to enjoy various VR services where rendering is
   carried out in the cloud.

   Cloud VR service experience is impacted by several factors that
   influence the achieved sense of reality, interaction, and immersion,
   which are related to the network properties, e.g. bandwidth, latency
   and packet loss.  The network performance indicators, such as
   bandwidth, latency, and packet loss rate, need to meet the
   requirements to realize a pleasurable experience.





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   The current network may be able to support early versions of cloud VR
   (e.g. 4K VR) with limited user experience, but will not meet the
   requirements for large scale deployment of cloud VR with enhanced
   experience (e.g.  Interactive VR applications, cloud games).  To
   support more applications and ensure a high-quality experience, much
   higher available and guaranteed bandwidth (e.g. larger than 1 Gbps),
   lower latency (e.g. less than 10 ms) and lower jitter (e.g. less than
   5 ms) are required.

3.  Requirement and problem Statement

3.1.  LxVPN over optical networks for multiple-to-multiple access

   L2VPN or L3VPN are used as overlay services on an optical network to
   support multi-cloud access.  Therefore, it is required for optical
   networks as underlay to support multipoint-to-multipoint (MP2MP)
   connections.

3.2.  Service-awareness

   Overlay packet-based services are usually configured separately from
   the configuration of underly connections in optical networks.  The
   connections in optical networks are treated as static connections for
   packet routing, therefore, they usually result in suboptimal routing
   of traffic and inefficient use of network resources at both packet
   and optical layer, making the network unable to adapt to dynamic
   network traffic changes.

   To support carrying dynamic cloud traffic, an optical network should
   be capable of understanding the traffic type and patterns, as well as
   the bandwidth and QoS requirement of the traffic, and map the traffic
   onto the best feasible connections in the optical network.  This
   requires both the control and management plane of optical networks to
   be able to sense the traffic and exchange the feasible QoS of
   underlay optical connections with the packet layer, such that the
   packet layer can make the best route selection.

3.3.  Deterministic performance

   Accessing cloud-based services requires deterministic performance
   from the underlay optical networks in order to achieve good user
   experience.  Connections built on optical networks need to be
   deterministic in many quality factors, such as end-to-end latency,
   delay jitter, bandwidth, and availability supported by end-to-end
   protection and restoration.  These deterministic performances are
   hard to reach on shared resources but can be achieved relatively
   easier on TDM-based optical networks.




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   Traditionally in an optical network, connections are pre-configured
   and the speed of dynamic restoration and reconfiguration of
   connections are in the order of several hundred milliseconds to
   several minutes.  The control and management plane of the optical
   network should be enhanced to significantly improve the speed of
   connection operations and be able to convey accurate estimate of the
   performance to the upper layer to achieve end-to-end deterministic
   performance.  Extensions to existing control plane and management
   interfaces are likely needed to support this capability.

3.4.  High performance and high reliability

   To support the above-mentioned applications some of the network
   properties are critical to promise the Quality of Services (QoS).
   For instance, high bandwidth (e.g. larger than 1 Gbps), low latency
   (e.g. no more than 10 ms) and low jitter (e.g. no more than 5 ms),
   are required for Cloud VR.  In addition, small-granularity container
   is required to improve the efficiency of the networks.

   It is also critical to support highly reliable DCI for cloud
   services.  With advanced optical transport network protection and
   automatic recovery technologies, services can still run properly even
   fiber cuts occur in the DCI network.  Specific protection and
   restoration schemes are required, to provide high reliability for the
   networks.

4.  Manageability Considerations

   TBD

5.  Security Considerations

   TBD

6.  IANA Considerations

   This document requires no IANA actions.

7.  References

7.1.  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,
              <https://www.rfc-editor.org/info/rfc2119>.





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   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

7.2.  Informative References

   [I-D.ietf-rtgwg-net2cloud-gap-analysis]
              Dunbar, L., Malis, A. G., and C. Jacquenet, "Networks
              Connecting to Hybrid Cloud DCs: Gap Analysis", Work in
              Progress, Internet-Draft, draft-ietf-rtgwg-net2cloud-gap-
              analysis-07, 26 July 2020,
              <https://www.ietf.org/archive/id/draft-ietf-rtgwg-
              net2cloud-gap-analysis-07.txt>.

   [I-D.ietf-rtgwg-net2cloud-problem-statement]
              Dunbar, L., Consulting, M., Jacquenet, C., and M. Toy,
              "Dynamic Networks to Hybrid Cloud DCs Problem Statement",
              Work in Progress, Internet-Draft, draft-ietf-rtgwg-
              net2cloud-problem-statement-11, 26 July 2020,
              <https://www.ietf.org/archive/id/draft-ietf-rtgwg-
              net2cloud-problem-statement-11.txt>.

Acknowledgments

   TBD

Authors' Addresses

   Sheng Liu
   China Mobile
   Email: liushengwl@chinamobile.com


   Haomian Zheng
   Huawei Technologies
   Email: zhenghaomian@huawei.com


   Aihua Guo
   Futurewei Technologies
   Email: aihuaguo.ietf@gmail.com


   Yang Zhao
   China Mobile
   Email: zhaoyangyjy@chinamobile.com





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