Internet DRAFT - draft-xiong-rtgwg-precise-tn-requirements
draft-xiong-rtgwg-precise-tn-requirements
RTGWG Q. Xiong
Internet-Draft ZTE Corporation
Intended status: Standards Track P. Liu
Expires: May 5, 2021 China Mobile
November 1, 2020
The Requirements for Precise Transport Networking
draft-xiong-rtgwg-precise-tn-requirements-01
Abstract
The future networks not only need to offer the Service Level
Agreements (SLA) guarantees such as low lantency and jitter, low
packet loss and high reliability, but also need to support the
precise services such as flexible resource allocation and service
isolation. This document proposes a set of performance requirements
and precise properties for Precise Transport Networking in various
industries such as 5G networks.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. Terms of Precise Transport Networking . . . . . . . . . . . . 3
4. Requirements of Precise Transport Networking . . . . . . . . 4
4.1. Precise Latency, Jitter, and Packet Loss . . . . . . . . 4
4.2. Precise SLA Guarantees for Converged Networks . . . . . . 4
4.3. Precise Resource Allocation . . . . . . . . . . . . . . . 4
4.4. Precise Service Isolation . . . . . . . . . . . . . . . . 5
4.5. Precise OAM . . . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Normative References . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
5G network is oriented to the internet of everything. In addition to
the Enhanced Mobile Broadband (eMBB) and Massive Machine Type
Communications(mMTC) services, it also supports the Ultra-reliable
Low Latency Communications (uRLLC) services. The uRLLC services
cover the industries such as intelligent electrical network,
intelligent factory, internet of vehicles, industry automation and
other industrial internet scenarios, which is the key demand of
digital transformation of vertical domains. These uRLLC services
demand SLA guarantees such as low latency and high reliability and
other deterministic and precise properties.
For the intelligent electrical network, there are deterministic
requirements for communication delay, jitter and packet loss rate.
For example, in the electrical current difference model, a delay of
3~10ms and a jitter variation is no more than 100us are required.
The isolation requirement is also important. For example, the
automatic operation, control of a process, isochronous data and low
priority service need to meet the requirements of hard isolation. In
addition to the requirements of delay and jitter, the differential
protection (DP) service needs to be isolated from other services.
The industrial internet is the key infrastructure that coordinate
various units of work over various system components, e.g. people,
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machines and things in the industrial environment including big data,
cloud computing, Internet of Things (IOT), Augment Reality (AR),
industrial robots, Artificial Intelligence (AI) and other basic
technologies. For example, automation control is one of the basic
application and the the core is closed-loop control system. The
control process cycle is as low as millisecond level, so the system
communication delay needs to reach millisecond level or even lower to
ensure the realization of precise control. There are three levels of
real-time requirements for industrial interconnection: factory level
is about 1s, and process level is 10~100ms, and the highest real-time
requirement is motion control, which requires less than 1ms.
The future networks not only need to offer the Service Level
Agreements (SLA) guarantees such as low latency and jitter, low
packet loss and high reliability, but also need to support the
precise services such as flexible resource allocation and service
isolation. This document proposes a set of performance requirements
and precise properties for Precise Transport Networking in various
industries such as 5G networks.
2. Conventions used in this document
2.1. Terminology
The terminology is defined as [RFC8655].
2.2. 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.
3. Terms of Precise Transport Networking
IEEE 802.1 Time-Sensitive Networking (TSN) has been proposed to
provide bounded latency and jitter in L2 LAN networks. According to
[RFC8655], Deterministic Networking (DetNet) operates at the IP layer
and delivers service with extremely low data loss rates and bounded
latency.
However, under the existing IP network architecture with statistical
multiplexing characteristics, the existing deterministic technologies
are facing long-distance transmission, queue scheduling, dynamic
flows and other controversial issues as described in [xiong-rtgwg-
precise-tn-problem-statement]. And besides precise latency, jitter,
and packet loss, more other precise and deterministic properties and
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performances should be provided such as flexible resource allocation
and service isolation and so on.
Precise Transport Networking is defined to provide precise SLA
guarantees such as latency, jitter, packet loss rate, reliability,
and precise control such as flexible resource allocation and service
isolation and more other precise services intelligently and
dynamically. The purpose of the Precise Transport Networking is
based on the hierarchical structure of the transport network, taking
advantage of the existing technologies including the flexible precise
tunnels technology and the deterministic mechanisms, to support the
end-to-end precise service through the characteristics of slicing
pieces, hard isolation and preemption characteristics, so as to
achieve the high-precision of the future networks.
4. Requirements of Precise Transport Networking
4.1. Precise Latency, Jitter, and Packet Loss
It is required to provide precise Latency, jitter and packet loss
dynamically and flexibly in all scenarios for each characterizd flow.
The precise requirements of latency includes bounded latency and low
latency. The precise requirements of jitter includes bounded jitter
and low jitter. So the precise requirements of latency and jitter
may be the combination of latency and jitter, typically including
bounded latency and low jitter, low latency and bounded latency, and
so on.
4.2. Precise SLA Guarantees for Converged Networks
It is required to provide precise SLA guarantees for converged
networks including computing and network convergence, lossless and
network convergence, etc.
In some scenarios, such as MEC, it is required to provide precise
computing for Controlized CFN/APN. Other resources such as computing
resources, energy consumption should be considered. And the
utilization and optimization of network resources are extremely
important.
4.3. Precise Resource Allocation
As described in [RFC8655], the primary means by which DetNet achieves
its QoS assurances is to reduce, or even completely eliminate, packet
loss by the provision of sufficient buffer storage at each node. But
it can not be achieved by not sufficient resource which can be
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allocated due to practical and cost reason. The existing solutions
can not achieve the precise resource allocation.
Precise resource allocation is required along with the explicit path
with more SLA guarantee parameters like bandwidth, latency, packet
loss and so on. The existing technologies such as FlexE and SR
tunnels should be taken into consideration.
4.4. Precise Service Isolation
It is required to provide precise service isolation for every flow.
In some scenarios, such as intelligent electrical network, the
isolation requirements are very important. For example, the
automatic operation or control of a process or isochronous data and
service with different priorities need to meet the requirements of
hard isolation. In addition to the requirements of delay and jitter,
the differential protection (DP) service needs to be isolated from
other services and hard isolated tunnel is required.
4.5. Precise OAM
It is required to consider precise service performance detection and
perception, service support and recovery mechanisms, such as
millisecond level service monitoring, 0.0001% packet loss awareness,
etc. The existing solutions also do not consider the statistics,
analysis and reporting of service performance.
Precise OAM is required including service monitoring, perception,
performance statistics, precise service support and recovery
mechanism, etc. The OAM mechanisms should be taken into
consideration such as In-band OAM, iOAM and so on.
5. Security Considerations
TBA
6. Acknowledgements
TBA
7. IANA Considerations
TBA
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8. 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>.
[RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", RFC 8655,
DOI 10.17487/RFC8655, October 2019,
<https://www.rfc-editor.org/info/rfc8655>.
Authors' Addresses
Quan Xiong
ZTE Corporation
No.6 Huashi Park Rd
Wuhan, Hubei 430223
China
Email: xiong.quan@zte.com.cn
Peng Liu
China Mobile
Beijing 100053
China
Email: liupengyjy@chinamobile.com
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