Problem Statement and Requirements of Accessing Cloud via Optical Network
draft-liu-ccamp-optical2cloud-problem-statement-00
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draft-liu-ccamp-optical2cloud-problem-statement-00
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
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This Internet-Draft will expire on 8 September 2022.
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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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