Internet DRAFT - draft-liu-rtgwg-optical2cloud-problem-statement
draft-liu-rtgwg-optical2cloud-problem-statement
RTGWG Working Group S. Liu
Internet-Draft China Mobile
Intended status: Standards Track H. Zheng
Expires: April 28, 2022 Huawei Technologies
October 25, 2021
Accessing Cloud via Optical Network Problem Statement
draft-liu-rtgwg-optical2cloud-problem-statement-00
Abstract
This document describes the scenarios and requirements for the Cloud
accessing through optical network, as a complementary functionality
of the network and cloud coordination. The problem from optical
perspective is different with packet, and statement is made in this
document.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 3
2. Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Multi-cloud accessing . . . . . . . . . . . . . . . . . . . 3
2.2. High-quality leased line . . . . . . . . . . . . . . . . . 4
2.3. Cloud virtual reality . . . . . . . . . . . . . . . . . . . 5
3. Requirement and Problem statement . . . . . . . . . . . . . . 5
3.1. LxVPN of optical networks for multiple-to-multiple access . 5
3.2. Small Granularity Switching . . . . . . . . . . . . . . . . 6
3.3. High-performance and high-reliability . . . . . . . . . . . 6
4. Manageability Considerations . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . . 7
7.2. Informational References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
The cloud-related applications is becoming popular and wider
deployed, in enterprises and vertical industries. Companies with
multi-campus are interconnected together with the remote cloud, for
the purpose of storage and computation. Such cloud services require
high-level experiences including high availability, low latency, on-
demand adjustment and so on.
Optical is playing an important role in the transport network, with
its own large bandwidth and low latency feature. Based on the TDM
switching technology, the data transportation in optical networks
does not have any queuing problem to solve and can perfectly avoid
congestion. Such features can drastically improve the users
experience on the service quality.
Optical network is considered as the transportation solution for
long-distance. This feature is also suitable for the cloud
interconnections, especially when there is demand for large
bandwidth.
[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, and
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it is expected the description in this document can be used as a
complementary from the optical 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 accessing
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 (Optical Transport Network) for
DCIs.
//------\\ /----\
||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
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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.
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 asfinancial, medical centers and education
customers. The main advantages and drivers of the high quality
private line are as follows.
o High quality private lines provide large bandwidth, low latency,
secure and reliable for any type of connection.
o 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.
o 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.
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o 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
Cloud Virtual Reality (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.
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 of optical networks for multiple-to-multiple access
To establish MP2MP connections, TDM transport technologies, like OTN,
are adopting packet features. Some OTN equipments have adopted
packet processing functions, such as packet switching, MPLS VPN,
etc., which could provide an underlay performance guaranteed TDM
channel for cloud accessing, as an alternative of packet-based
connections.
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3.2. Small Granularity Switching
Accroding to the ITU-T G.709 recommendation, the OTN is providing TDM
based connection with a granularity 1.25Gbps, which is more than the
demand for normal user. Most of the leased line is requesting a
bandwidth less than 10Mbps, and the request from big enterprises are
usually on the level of 100Mbps. Therefore, most of the leased lines
are with small granularity in the field.
The SDH was a good complementary of OTN for small granularity
solution, but SDH devices are gradually removed from the network due
to End of Services. As SDH networks gradually phase out, service
providers start to think about how to utilize OTN networks to
transmit small-granularity high-value SDH services. The OSU (optical
service unit) is proposed to solve the problem.
At ITU-T, two work items, G.sub1G.sup and G.OSU, have been initiated
aiming to enable OTN to support small-granularity services of 2M-1Gb/
s. For G.OSU, the general idea is to put small granularity services
into OSU containers, and then put OSU containers into OPU payload
areas. OSU containers are flagged by Tributary Port Number (TPN)
tags located at the overhead of the OSU containers. At the
intermediate nodes, OSUs can be switched to different directions
based on the TPN tags in the overhead. Given the development of OSU,
the OTN is expected to be able to carry small granularity service and
create end-to-end optical connections.
3.3. 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.
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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>.
[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. Informational References
[I-D.ietf-rtgwg-net2cloud-gap-analysis]
Dunbar, L., Malis, A. G., and C. Jacquenet, "Networks
Connecting to Hybrid Cloud DCs: Gap Analysis", draft-ietf-
rtgwg-net2cloud-gap-analysis-07 (work in progress), July
2020.
[I-D.ietf-rtgwg-net2cloud-problem-statement]
Dunbar, L., Consulting, M., Jacquenet, C., and M. Toy,
"Dynamic Networks to Hybrid Cloud DCs Problem Statement",
draft-ietf-rtgwg-net2cloud-problem-statement-11 (work in
progress), July 2020.
Authors' Addresses
Sheng Liu
China Mobile
China
Email: liushengwl@chinamobile.com
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Haomian Zheng
Huawei Technologies
H1, Xiliu Beipo Village, Songshan Lake,
Dongguan, Guangdong 523808
China
Email: zhenghaomian@huawei.com
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