Internet DRAFT - draft-li-nmrg-dtn-addressing-protocols
draft-li-nmrg-dtn-addressing-protocols
nmrg G. Li
Internet-Draft Huawei
Intended status: Informational C. Zhou
Expires: 28 April 2022 China Mobile
25 October 2021
Opportunities of Flexible Addressing and Protocols in Digital Twin
Network
draft-li-nmrg-dtn-addressing-protocols-00
Abstract
To build digital twin networks based on the digital twin network
architecture in [DTNConcept], modeling of digital twins and virtual-
physical mapping are critical. There are many ways to construct
network twins, and they have different ways to realize virtual-
physical mapping and information exchange between twins.
Constructing a twin of network element that has communication
requirement and function like a physical entity is a kind of network
modeling. In this scenario, when implementing virtual-physical
mapping and information exchange between twins based on network layer
communication, It faces problems such as large addressing space
consumption and low addressing efficiency.
This document describes an idea to using flexible addressing and
protocol techniques in digital twin network architecture that can
help reduce the complexity of digital twin network implementations
and improve digital twin network efficiency and security.
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
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 28 April 2022.
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Copyright Notice
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 3
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Flexible Addressing for DTN . . . . . . . . . . . . . . . . . 4
4.1. Communication between Physical Network Entities . . . . . 5
4.2. Communication between Digital Twins . . . . . . . . . . . 5
4.3. Communication between Physical Network Entities and Digital
Twins . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Flexible Protocols for DTN . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. IANA Considerations {#SEC:iana}. . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
With the development of digital transformation, the network scale
becomes larger and larger, and the types of network and network
services become more complex. To improve the efficiency of network
planning, construction, maintenance, and optimization, the digital
twin technology is introduced into the network field to implement
intelligent and automated networks. In [DTNConcept], a digital twin
network is defined as a virtual representation of the physical
network. In almost all digital twin use cases, real-time connections
between physical entities and digital twins are necessary.
In order to implement the mapping between network physical entities
and digital twins, various data collection technologies are proposed
[DTNTechs], such as the mature and widely used SNMP (Simple network
management protocol) and NETCONF, which can collect NetFlow and sFlow
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of original code streams. Supports network telemetry in push mode on
the data source side. Different data collection solutions have
different characteristics and are applicable to different application
scenarios. However, these data collection methods depend on the
complex mapping models to act on the correct object, resulting in
poor readability of the data.
In order to be compatible with device interfaces and configuration
models of different vendors, those modelings of mapping needs to
define complex data acquisition protocols and perform data parsing
and conversion at the application layer,which increases the
information transmission delay of the digital twin network.
Constructing a twin of network element that has communication
requirement and function like a physical entity is another modeling
of mapping. It provides requirements of implementing virtual-
physical mapping and information exchange between twins based on
network layer communication.
This document proposes a flexible network addressing technique to
solve the problem of mapping network physical entities to digital
twins. The physical network domain and the twin network domain use
the same address configuration, that is, any network entity and its
corresponding digital twin use the same IP address. Different NIA
(Network Index Addresses) are allocated to different domains. The
NIA and IP address of network element together constitute a globally
unique communication identifier. In addition, a programmable
flexible network layer protocol is used to carry communication
traffic between physical entities and digital twins. Communication
between network elements and between physical network elements and
their digital twins is distinguished by using different addresses,
and fields with different security levels are applied to network
packet headers. Therefore, the state synchronization efficiency and
security of the digital twin network are improved.
2. Requirements Notation
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] and [RFC8174] when, and only when, they appear in all
capitals, as shown here.
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3. Overview
Currently, IPv6 (Internet Protocol version 6) is being deployed more
and more. As the network scale increases, the distribution of IPv6
addresses will become more fragmented. If a 1:1 real-time digital
twin network needs to be implemented, it is the most natural way to
create an independent mirror IPv6 space for the digital twin network
domain. However, the digital twin network architecture requires
real-time state synchronization between the physical network layer
and the twin network layer, which requires that the network physical
entity and the network digital twin have unique network communication
identifiers. Different NIAs are allocated to the physical network
domain and the twin network domain to implement unique identifiers.
During running of a digital twin network, communication between
physical network entities, between network twins, and between
physical network entities and network twins has different functions.
However, the format of IPv6 is relatively fixed, and it is difficult
to reflect characteristics of communication traffic in the digital
twin network. In addition, security requirements for these
communications are different. IPv6-based security protocols cannot
flexibly configure security for data flows. Therefore, a flexible
and extensible Internet communication protocol will be able to solve
the above problems. First, the communication subject needs to carry
a trusted digital identity in the data packet header. The network
can efficiently differentiate traffic and guarantee QoS based on the
digital identity. In addition, composite attributes such as a
digital identity, a verification identifier, and a communication
policy identifier may be flexibly carried in a data packet header.
In this way, the communication between the physical IPv6 domain and
the mirrored IPv6 domain can be implemented through a unified network
layer protocol.
4. Flexible Addressing for DTN
The mapping between digital twins and underlying entities is one of
the four key elements of digital twin networks. Conceptually,
mapping needs to include one-to-one mapping and one-to-many mapping,
but one-to-one mapping helps achieve clearer digital twins and
facilitates real-time network state synchronization. When a digital
twin network validates a new technology, there may also be multiple
network digital twins corresponding to the same physical network.
One-to-one mapping makes this easier.
The use of IPv6 as a communication identifier in physical networks
has become a common understanding, and this is a technical
requirement for many legacy networks. However, for new digital twin
networks, using the same IPv6 address space will incur additional
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mapping storage overhead. It is also not particularly readable for
network O&M personnel. In this case, providing a separate address
space for each digital twin of the physical network so that the
digital twin can use the same IPv6 address as its corresponding
physical entity greatly simplifies network operation complexity.
Considering that in the case of one-to-one mapping, a continuous data
flow is required between the physical entity and the digital twin to
synchronize state, a globally unique identifier needs to be allocated
to both parties in a communication process. To address this issue,
this document introduces the concept of Network Index Address (NIA).
The NIA uniquely identifies a network address space. For example, an
IPv6 address space identifier of a physical network is 0x86, and an
IPv6 address space identifier of a digital twin network is 0x96,
0xa6.
For the three communication models, the communication protocol uses
different forms of network address to identify the source and
destination.
4.1. Communication between Physical Network Entities
Native IPv6 protocols and addresses can be used for communication.
4.2. Communication between Digital Twins
You can use independent IPv6 addresses for internal communication.
Digital twins are generally carried on physical computing platforms.
Therefore, when cross-physical-platforms communication is involved,
how traffic in the digital twin space transit through physical
network space needs to be considered.
4.3. Communication between Physical Network Entities and Digital Twins
Because the communication parties are located in different address
spaces, a combined NIA and IPv6 address is used as the identifier of
the communication subject.
5. Flexible Protocols for DTN
In a digital twin network system, traffic will have multiple levels
of significance. such as traditional physical network traffic,
traffic between digital twins, and state synchronization traffic
between physical entities and digital twins. These types of traffic
have different requirements for reliability, security, and real-time
communication. However, the devices carrying the traffic are highly
overlapped. Therefore, a unified protocol is required for
interconnection. As mentioned earlier, in these communication
models, the form of source and destination addresses goes beyond IPv6
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addresses. At the same time, the diversified requirements for
security, real-time performance and network policies also require
better scalability and security of network protocols.
Flexible network protocols can meet the preceding requirements to the
maximum extent. First, in the digital twin network, it is required
that all virtual and physical elements have globally trusted
identities. The identity may be used to sign a network instruction
and monitoring data, and may be further used to generate a key to
encrypt a key network parameter or status information. On the basis
of trusted identity, the along path verification mechanism can
efficiently verify the validity of traffic, thereby achieving higher
security.
Adding a digital identifier to a packet header facilitates refined
traffic engineering and management policies according to these
identifiers, and facilitates fast implementation of complex digital
twin network applications. Based on scalable and flexible protocols,
deterministic network technologies can be customized in packets to
achieve real-time network communication.
6. Security Considerations
The independent address space and flexible protocol encapsulation
allow you to customize different security levels for different
traffic. In particular, the mechanism of trusted identity can
effectively detect illegal traffic and block it as early as possible,
which enhances the security of digital twin networks. However, new
address modes and protocols may break traditional end-to-end security
mechanisms.
7. IANA Considerations {#SEC:iana}.
In this document, it needs to apply for new registry for the NIA and
apply for NIA numbers for protocols such as IPv6.
8. References
8.1. 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>.
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8.2. Informative References
[DTNConcept]
"Digital Twin Network: Concepts and Reference
Architecture", n.d., <https://datatracker.ietf.org/doc/
draft-zhou-nmrg-digitaltwin-network-concepts/>.
[DTNTechs] Sun Tao, Zhou Cheng, Duan Xiao-Dong, Lu Lu, Chen Dan-Yang,
Yang Hong-Wei, Zhu Yan-Hong, Liu Chao, Li Qin, Wang Xiao,
Shen Zhen, Qu Feng-Zhong, Jiang Huai-Guang, Wang Fei-Yue,
., "Digital twin network (DTN): concepts, architecture,
and key technologies", June 2021, <Acta Automatica Sinica,
2021, 47(3): 569-582 DOI: 10.16383/j.aas.c210097>.
Authors' Addresses
Guangpeng Li
Huawei Technologies
Beiqing Road, Haidian District
Beijing
100095
China
Email: liguangpeng@huawei.com
Cheng Zhou
China Mobile
No. 53, Xibianmen Inner Street, Xicheng District
Beijing
100053
China
Email: zhouchengyjy@chinamobile.com
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