Internet-Draft Differentiated DetNet QoS for Determinis June 2024
Xiong, et al. Expires 29 December 2024 [Page]
Workgroup:
DetNet
Internet-Draft:
draft-xiong-detnet-differentiated-detnet-qos-01
Published:
Intended Status:
Informational
Expires:
Authors:
Q. Xiong, Ed.
ZTE Corporation
J. Zhao
CAICT
Z. Du
China Mobile
Q. Zeng
China Telecom
C. Liu
China Unicom

Differentiated DetNet QoS for Deterministic Services

Abstract

This document describes the service requirements of scaling deterministic networks and proposes Differentiated DetNet QoS (DD-QoS) for deterministic services in enhanced DetNet.

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 https://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."

This Internet-Draft will expire on 29 December 2024.

Table of Contents

1. Introduction

According to [RFC8655], Deterministic Networking (DetNet) operates at the IP layer and delivers service which provides extremely low data loss rates and bounded latency within a network domain. The DetNet Quality of Service (QoS) includes the bounded latency indicating the minimum and maximum end-to-end latency from source to destination and bounded jitter (packet delay variation). Three techniques are used by DetNet to provide these qualities of service including service protection, explicit routes and resource allocation.

[I-D.ietf-detnet-scaling-requirements] has mentioned the enhanced DetNet should support different levels of application requirements which is important for the DetNet deployment. [I-D.zhao-detnet-enhanced-use-cases] has described enhanced use cases and network requirements for scaling deterministic networks and seven levels of typical applications have been defined. Different levels of applications differ in the network ranges and SLAs requirements. Moreover, multiple services and traffic flows with different bounded latency requirements may be also co-existed in the same application. Multiple deterministic services may demand different set of SLAs and it may define more than one DetNet QoS levels according to different application scenarios. These flows should be transmitted and forwarded with different DetNet QoS behaviors. From the use cases in [RFC8578], DetNet applications differ in their network topologies and specific desired behavior and different services requires differentiated DetNet QoS.

This document describes the service requirements of scaling deterministic networks and proposes Differentiated DetNet QoS (DD-QoS) for deterministic services in enhanced DetNet.

1.1. 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].

2. Terminology

The terminology is defined as [RFC8655].

DD-QoS: Differentiated DetNet QoS

DC: DetNet Traffic Class

3. Service Requirements of Scaling Deterministic Networks

3.1. Support Different Levels of Applications Co-existed with Differentiated SLAs

5G network is oriented to the internet of everything. It need to supports the Ultra-reliable Low Latency Communications (uRLLC) services. The uRLLC services demand SLA guarantees such as low latency and high reliability and other deterministic and precise properties especially in Wide Area Network (WAN) applications.The uRLLC services should be provided in large-scale networks which cover the industries such as intelligent electrical network, intelligent factory, internet of vehicles, industry automation and other industrial internet scenarios. The industrial internet is the key infrastructure that coordinate various units of work over various system components, e.g. people, 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 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. For the automation control, it 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. So the deterministic latency requirements are different with varying services and network scenarios.

As per [I-D.zhao-detnet-enhanced-use-cases], various deterministic applications are co-existed with different SLAs guarantees in scaling networks and these applications can be classified into different levels. As per [I-D.ietf-detnet-scaling-requirements], the enhanced DetNet should support different levels of application requirements and different levels of deterministic applications demand different DetNet technologies in scaling deterministic networks. As defined in [RFC8655], the DetNet QoS can be expressed in terms of : Minimum and maximum end-to-end latency, bounded jitter (packet delay variation), packet loss ratio and an upper bound on out-of-order packet delivery. As described in [RFC8578], DetNet applications differ in their network topologies and specific desired behavior and different services requires differentiated DetNet QoS. In large-scale networks, multiple services with differentiated DetNet QoS can be co-existed in the same DetNet network. The classification of the deterministic flows within different levels should be taken into considerations. It is required to provide Latency, bounded jitter and packet loss dynamically and flexibly in all scenarios for each characterized flow.

As the Figure 1 shows, the services can be divided into 5 levels and level 2~5 is the DetNet flows and level-1 is non-DetNet flow. DetNet applications and DetNet QoS is differentiated within each level.


+--------------+---------+-----------+-----------+----------+------------+
| Item         | Level-1 | Level-2   | Level-3   | Level-4  |  Level-5   |
+--------------+---------+-----------+-----------+----------+------------+
|Applications  |Email    |  Voice    | Audio and | AR/VR    | Industrial |
|Examples      |         |           | Video     |          |            |
+--------------+---------+-----------+-----------+----------+------------+
|Differentiated|N/A      |delay<300ms|delay<50ms |delay<20ms|delay<10ms  |
|SLAs          |         |jitter<50ms|jitter<50ms|jitter<5ms|jitter<100us|
+--------------+---------+-----------+-----------+----------+------------+
|DetNet QoS    |Bandwidth|Jitter     | Delay     | Low      | Ultra-low  |
|Forwarding    |Guarantee|Guarantee  | Guarantee | delay    |  delay and |
|Behaviors     |         |           |           |and jitter|  jitter    |
+--------------+---------+-----------+-----------+----------+------------+


Figure 1: The classification of Different Levels of Applications

From the perspective of deterministic service requirements, deterministic QoS in the network can be divided into five types or levels:

Level-1: bandwidth guarantee. The indicator requirements include basic bandwidth guarantee and certain packet loss tolerance. There is no requirement for the upper bound of the latency, and no requirement for the jitter. Typical services include download and FTP services.

Level-2: jitter guarantee. The indicator requirements include: jitter<50ms, delay<300ms. Typical services include synchronous voice services, such as voice call.

Level-3: delay guarantee. The indicator requirements include: delay<50ms, jitter<50ms. Typical services include real-time communication services, such as video, production monitoring, and communication services.

Level-4: low delay and jitter guarantee. The indicator requirements include: delay<20ms, jitter<5ms. Typical services include video interaction services, such as AR/VR, holographic communication, cloud video and cloud games.

Level-5: ultra-low delay and jitter guarantee. The indicator requirements include: delay<10ms, jitter<100us. Typical services include production control services, such as power protection and remote control.

Moreover, different DetNet services is required to tolerate different percentage of packet loss ratio such as 99.9%, 99.99%, 99.999%, and so on.

3.2. Support High Utilization of Network Resources

Traditional Ethernet, IP and MPLS networks which is based on statistical multiplexing provides best-effort packet service and offers no delivery and SLA guarantee. As described in [RFC8655], the primary technique by which DetNet achieves its QoS is to allocate sufficient resources. But it can not be achieved by not sufficient resource which can be allocated due to practical and cost reason. So it is required to achieve the high-efficiency of resources utilization when provide the DetNet services.

4. Pre-defined Classes for Differentiated DetNet QoS

As per [RFC8655], an important goal of the DetNet QoS is the bounded latency including the minimum and maximum end-to-end latency from source to destination, and bounded jitter. From the services requirements, a scaling network in enhanced DetNet needs to provide the deterministic services for various applications. The deterministic services may demand differentiated SLAs and different bounded latency guarantees. So multiple DetNet QoS levels should be supported according to different application scenarios. Moreover, as per [RFC8938], the aggregation of individual flows may be still challenging for network operations with a large number of deterministic flows and network nodes in large-scale networks. It may provide aggregation based on pre-defined classes to resolve the scaling issues.

The differentiated QoS MAY be classified based on the applications in scaling networks. This document proposed the DetNet Traffic Class (DC) to indicate the pre-defined classes for Differentiated DetNet QoS (DD-QoS). The DetNet traffic class may be divided into 4 types:


   +--------------+-----------+----------+----------+-----------+-----------+
   |Differentiated| Bandwidth | Jitter   | Delay    | Low       | Ultra-low |
   |DetNet QoS    | Guarantee | Guarantee| Guarantee| delay and |  delay and|
   |Forwarding    |           |          |          | and jitter|  jitter   |
   |Behaviors     |           |          |          |           |           |
   +--------------+-----------+----------+----------+-----------+-----------+
   | DetNet       |           |          |          |           |           |
   | Traffic      |Best-effort|  DC-1    |  DC-2    |  DC-3     |   DC-4    |
   | Class        |           |          |          |           |           |
   +--------------+-----------+----------+----------+-----------+-----------+
Figure 2: Traffic class for Differentiated DetNet QoS

Different QoS class indicates different levels of applications with SLAs requirements and each class demands differentiated QoS behaviors as well as different DetNet capabilities in scaling network. For example, the behaviors of jitter guarantee and delay guarantee may implement different queuing mechanisms. Each QoS class can be divided into serveral sub-classes based on the SLAs requirements of the applications.

5. Security Considerations

Security considerations for DetNet are covered in the DetNet Architecture [RFC8655] and DetNet data plane [RFC8938], [RFC8939], [RFC8964] and DetNet security considerations [RFC9055]. The security considerations specified in [I-D.ietf-detnet-scaling-requirements] are also applicable to the procedures defined in this document.

6. IANA Considerations

There might be no IANA register request in this document.

7. Acknowledgements

The authors would like to acknowledge Tianji Jiang, Aihua Liu, Bin Tan for the thorough review and very helpful comments.

8. References

8.1. Normative References

[I-D.ietf-detnet-scaling-requirements]
Liu, P., Li, Y., Eckert, T. T., Xiong, Q., Ryoo, J., zhushiyin, and X. Geng, "Requirements for Scaling Deterministic Networks", Work in Progress, Internet-Draft, draft-ietf-detnet-scaling-requirements-06, , <https://datatracker.ietf.org/doc/html/draft-ietf-detnet-scaling-requirements-06>.
[I-D.zhao-detnet-enhanced-use-cases]
Zhao, J., Xiong, Q., and Z. Du, "Enhanced Use cases for Scaling Deterministic Networks", Work in Progress, Internet-Draft, draft-zhao-detnet-enhanced-use-cases-00, , <https://datatracker.ietf.org/doc/html/draft-zhao-detnet-enhanced-use-cases-00>.
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC4655]
Farrel, A., Vasseur, J.-P., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC 4655, DOI 10.17487/RFC4655, , <https://www.rfc-editor.org/info/rfc4655>.
[RFC4915]
Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", RFC 4915, DOI 10.17487/RFC4915, , <https://www.rfc-editor.org/info/rfc4915>.
[RFC5120]
Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi Topology (MT) Routing in Intermediate System to Intermediate Systems (IS-ISs)", RFC 5120, DOI 10.17487/RFC5120, , <https://www.rfc-editor.org/info/rfc5120>.
[RFC5440]
Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, DOI 10.17487/RFC5440, , <https://www.rfc-editor.org/info/rfc5440>.
[RFC6549]
Lindem, A., Roy, A., and S. Mirtorabi, "OSPFv2 Multi-Instance Extensions", RFC 6549, DOI 10.17487/RFC6549, , <https://www.rfc-editor.org/info/rfc6549>.
[RFC7752]
Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and S. Ray, "North-Bound Distribution of Link-State and Traffic Engineering (TE) Information Using BGP", RFC 7752, DOI 10.17487/RFC7752, , <https://www.rfc-editor.org/info/rfc7752>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
[RFC8231]
Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path Computation Element Communication Protocol (PCEP) Extensions for Stateful PCE", RFC 8231, DOI 10.17487/RFC8231, , <https://www.rfc-editor.org/info/rfc8231>.
[RFC8233]
Dhody, D., Wu, Q., Manral, V., Ali, Z., and K. Kumaki, "Extensions to the Path Computation Element Communication Protocol (PCEP) to Compute Service-Aware Label Switched Paths (LSPs)", RFC 8233, DOI 10.17487/RFC8233, , <https://www.rfc-editor.org/info/rfc8233>.
[RFC8578]
Grossman, E., Ed., "Deterministic Networking Use Cases", RFC 8578, DOI 10.17487/RFC8578, , <https://www.rfc-editor.org/info/rfc8578>.
[RFC8655]
Finn, N., Thubert, P., Varga, B., and J. Farkas, "Deterministic Networking Architecture", RFC 8655, DOI 10.17487/RFC8655, , <https://www.rfc-editor.org/info/rfc8655>.
[RFC8664]
Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., and J. Hardwick, "Path Computation Element Communication Protocol (PCEP) Extensions for Segment Routing", RFC 8664, DOI 10.17487/RFC8664, , <https://www.rfc-editor.org/info/rfc8664>.
[RFC8938]
Varga, B., Ed., Farkas, J., Berger, L., Malis, A., and S. Bryant, "Deterministic Networking (DetNet) Data Plane Framework", RFC 8938, DOI 10.17487/RFC8938, , <https://www.rfc-editor.org/info/rfc8938>.
[RFC8939]
Varga, B., Ed., Farkas, J., Berger, L., Fedyk, D., and S. Bryant, "Deterministic Networking (DetNet) Data Plane: IP", RFC 8939, DOI 10.17487/RFC8939, , <https://www.rfc-editor.org/info/rfc8939>.
[RFC8964]
Varga, B., Ed., Farkas, J., Berger, L., Malis, A., Bryant, S., and J. Korhonen, "Deterministic Networking (DetNet) Data Plane: MPLS", RFC 8964, DOI 10.17487/RFC8964, , <https://www.rfc-editor.org/info/rfc8964>.
[RFC9055]
Grossman, E., Ed., Mizrahi, T., and A. Hacker, "Deterministic Networking (DetNet) Security Considerations", RFC 9055, DOI 10.17487/RFC9055, , <https://www.rfc-editor.org/info/rfc9055>.
[RFC9320]
Finn, N., Le Boudec, J.-Y., Mohammadpour, E., Zhang, J., and B. Varga, "Deterministic Networking (DetNet) Bounded Latency", RFC 9320, DOI 10.17487/RFC9320, , <https://www.rfc-editor.org/info/rfc9320>.
[RFC9357]
Xiong, Q., "Label Switched Path (LSP) Object Flag Extension for Stateful PCE", RFC 9357, DOI 10.17487/RFC9357, , <https://www.rfc-editor.org/info/rfc9357>.

Authors' Addresses

Quan Xiong (editor)
ZTE Corporation
China
Junfeng Zhao
CAICT
China
Zongpeng Du
China Mobile
China
Qimiao Zeng
China Telecom
China
Chang Liu
China Unicom
No.9 Shouti Nanlu
Beijing
100048
China