Internet Research Task Force H. Yang Internet-Draft C. Zhou Intended status: Informational China Mobile Expires: 24 April 2023 21 October 2022 Digital Twin Network Flow Simulation draft-yz-nmrg-dtn-flow-simulation-01 Abstract Some important application scenarios of digital twin network, such as network new technology experiment, network configuration verification, network performance optimization, etc., all require the virtual traffic in the twin network to accurately simulate the real traffic in the physical network.The real traffic in the physical network is called the physical traffic, and the virtual traffic in the twin network is called the twin traffic. In order to realize the high-fidelity simulation of the physical traffic by the twin traffic, this paper proposes that the twin traffic and the physical traffic should satisfy three consistent characteristics, and an implementation method of twin flow is introduced. 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 24 April 2023. Copyright Notice Copyright (c) 2022 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Yang & Zhou Expires 24 April 2023 [Page 1] Internet-Draft Digital Twin Network October 2022 Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions Used in This Document . . . . . . . . . . . . . . 4 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Requirements Language . . . . . . . . . . . . . . . . . . 4 3. Key characteristics of DTN flow . . . . . . . . . . . . . . . 4 4. DTN flow implementation method . . . . . . . . . . . . . . . 4 5. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 9 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 8. Normative References . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction Digital twin network is a virtual representation of the physical network. Such virtual representation of the network is meant to be used to analyze, diagnose, emulate, and then control the physical network based on data, models, and interfaces. The DTN architecture diagram is shown in Figure 1. Yang & Zhou Expires 24 April 2023 [Page 2] Internet-Draft Digital Twin Network October 2022 +---------------------------------------------------------+ | +-------+ +-------+ +-------+ | | | App 1 | | App 2 | ... | App n | Application| | +-------+ +-------+ +-------+ | +-------------^-------------------+-----------------------+ |Capability Exposure| Intent Input | | +-------------+-------------------v-----------------------+ | Instance of Digital Twin Network | | +--------+ +------------------------+ +--------+ | | | | | Service Mapping Models | | | | | | | | +------------------+ | | | | | | Data +---> |Functional Models | +---> Digital| | | | Repo- | | +-----+-----^------+ | | Twin | | | | sitory | | | | | | Network| | | | | | +-----v-----+------+ | | Mgmt | | | | <---+ | Basic Models | <---+ | | | | | | +------------------+ | | | | | +--------+ +------------------------+ +--------+ | +--------^----------------------------+-------------------+ | | | data collection | control +--------+----------------------------v-------------------+ | Physical Network | | | +---------------------------------------------------------+ Figure 1: Figure1:Reference Architecture of Digital Twin Network The digital twin layer forms a network element model by modeling physical network elements, and the network element model forms a twin network element through instantiation, that is, each physical network element in the physical network has a corresponding twin network element in the digital twin layer. Similarly, each physical flow of the physical network also has a corresponding twin flow at the digital twin layer. Through the real-time data interaction between the physical network and the twin network, the physical network elements, network topology, network traffic, network status and other data in the physical network are virtualized at the twin network layer. The topology of the physical network and the twin network are consistent, The number of NEs is the same, and the traffic information is the same. Yang & Zhou Expires 24 April 2023 [Page 3] Internet-Draft Digital Twin Network October 2022 2. Conventions Used in This Document 2.1. Terminology DTN Digital Twin Network 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. Key characteristics of DTN flow The twin network layer needs to accurately simulate the traffic of the physical network to support the normal operation of the network application layer.The twin traffic of the twin network layer and the physical traffic of the physical network need to satisfy the following three characteristics at the same time. 1) The two traffic forwarding paths are consistent, that is, the twin nodes that twin traffic passes through at the twin network layer are consistent with the physical nodes that physical traffic passes through at the physical network layer; 2) The network performance of the two types of traffic is consistent, that is, the twin traffic and the physical traffic have the same performance as network delay, packet loss, and jitter; 3) The two traffic data characteristics are consistent, that is, the data packets of twin traffic and physical traffic have the same key characteristics such as traffic rate, quintuple information, data packet length, and data packet priority; 4. DTN flow implementation method If the twin flow and physical flow are to meet the above three characteristics, three problems need to be solved: 1) The physical network element and the twin network element have unique identifiers in the entire network, so as to realize the mutual correspondence between the two. The physical traffic passes through those physical network elements, and the twin traffic also passes through the corresponding twin network element, so as to achieve the same forwarding path; Yang & Zhou Expires 24 April 2023 [Page 4] Internet-Draft Digital Twin Network October 2022 2) The physical flow is uniformly collected and managed by the Data Repository of the twin network layer, and then distributed to each twin network element. Because the time for each physical network element to complete data collection and data transmission is inconsistent, in order to ensure that the twin flow and physical flow have the same performance as forwarding delay, packet loss, and jitter, the twin flow must be delayed by a fixed time. That is, the twin flow delays the physical flow by a fixed time. 3) The flow data collected by the Data Repository should include the key information of physical flow, so that the twin flow and physical flow data characteristics are consistent; when the Data Repository collects physical flow, it can be collected in full package by package or partially collected at a certain sampling rate; +--------------------------------------------------------------+ | Digital Twin Network +----------+ | | +---------+ Twin NE 3+----------+ | | | +----------+ | | | | | | | -----------+ +-----+----+ +----------+ +-----+----+ | | | Twin NE 1+----+ Twin NE 2+----+ Twin NE 4+----+ Twin NE n| | | -----------+ +----------+ +----------+ +----------+ | | +-----------------+ | | | Data Repository | | | +-----------------+ | +--------------------------------------------------------------+ | +-------------------------------+------------------------------+ | Delay Deterministic Networking | +-------------------------------^------------------------------+ | +---------------------------------+---------------------------------+ | Phsical Network +------------+ | | +----------+Physical NE3+----------+ | | | +------------+ | | | | | | | +------------+ +-----+------+ +------------+ +------+-----+ | | |Physical NE1+---+Physical NE2+---+Physical NE4+---+Physical NEn| | | +------------+ +------------+ +------------+ +------------+ | +-------------------------------------------------------------------+ Figure 2: Figure 2: Twin Flow and Physical Flow For the above three problems, use the following three methods to solve: Yang & Zhou Expires 24 April 2023 [Page 5] Internet-Draft Digital Twin Network October 2022 1) Each physical network element has a system MAC address, because the MAC address is unique in the whole network and can be used as the identifier of the physical network element. The twin NE ID can be extended based on the physical NE ID. For example, an 8-bit custom field is added after the MAC address of the physical NE system, for example, to identify the device type. The twin NE is identified based on the MAC address of the physical NE, which not only realizes the one-to-one correspondence between the physical NE and the twin NE, but also realizes the unique identification of the twin NE in the entire network. 2) The data transmission network between the physical network element and the Data Repository uses a delay deterministic network, such as TSN (Time Sensitive Network), DIP (Deterministic Internet Network), etc. Since the delays of different physical network elements to transmit data to the Data Repository may be different, if a delay deterministic network is used, the data transmission delays T1~Tn are fixed and can be pre-calculated. After the Data Repository calculates T1~Tn, the maximum value Tmax is selected as the reference time. Assume that the data collected from each physical network element arrives at the Data Repository from t1 to tn. If the data transmission time Tn | | | | | | | | +-------------------------+ | | | | 2. Physical NEs|collect | | | | | key flow information | | | | | and form a data|set | | | | +-------------------------+ | | | | | | | | | | | 3.The|dataset is|sent to the Data Repository +---------------------->| | | | 4.The Data Repository sendsto | | the corresponding twin NE | | according to the NE identifier | | of the data|set | | | +----------->+ | | | | | | | +----------+---------------+ | | | | 5.The twin NEs generate | | | | | twin flow|according to | | | | | the data set information | | | | +----------+---------------+ | | | | Figure 3: Figure 3: The generation process of twin traffic 5. Conclusion This paper realizes high-precision simulation of DTN twin flow, so that twin flow and physical flow meet the following three characteristics: 1) The forwarding paths of the two types of flow are the same, that is, the nodes they pass through are the same; 2) The network performance of the two types of flow is the same, that is, the two have the same performance as network delay, packet loss, and jitter; Yang & Zhou Expires 24 April 2023 [Page 8] Internet-Draft Digital Twin Network October 2022 3) The data characteristics of the two types of flow are consistent, that is, they have the same key characteristics such as flow rate, five-tuple information, data packet length, and data packet priority. 6. Security Considerations TBD. 7. IANA Considerations TBD. 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, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . Authors' Addresses Hongwei Yang China Mobile Beijing 100053 China Email: yanghongwei@chinamobile.com Cheng Zhou China Mobile Beijing 100053 China Email: zhouchengyjy@chinamobile.com Yang & Zhou Expires 24 April 2023 [Page 9]