Requirements for Interfaces of
Network Digital TwinChina MobileBeijing100053Chinachendanyang@chinamobile.comChina MobileBeijing100053Chinayanghongwei@chinamobile.comChina MobileBeijing100053Chinazhouchengyjy@chinamobile.com
Networking
Internet Research Task ForceNetwork Digital Twin; interfaceThe interfaces of Digital Twin Network can be divided as twin network
southbound interface, internal interface and northbound interface. In
order to build a digital twin network and realize its many advantages,
different interfaces should be able to meet different requirements. And
this memo introduces the requirements for the interfaces of the Digital
Twin Network.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.As defined in the , the digital twin
network is defined as "a network system with a physical network entity
and a virtual twin, and the two can interact with each other in real
time". It should have four core elements: data, model, mapping and
interaction. Accordingly, a "three-layer, three-domain and double-closed
loop" architecture is adopted.) and the network telemetry technologyBased on the above architecture definition of three-layer,
three-domain and double-closed-loop, the interfaces of each layer and
their positions of the digital twin network are shown in Figure 1. The
network elements in the physical entity network exchange network data
and network control information with the twin network layer through the
twin southbound interface. The twin network layer contains three key
subsystems, which are data sharing warehouse, service mapping model and
digital twin management. Through the corresponding interface protocol,
the construction and interaction requirements of the three key
subsystems should be met. And through the internal interface of the twin
layer, the interaction between the three key subsystems and the physical
network layer and network application layer is realized. Network
applications input requirements to the twin network layer through the
twin northbound interface, and deploy services in the twin network layer
through the model example. To sum up, there are differences in interface
protocol requirements between different layers of DTN and within twin
layers.Twin northbound interfaceThe twin northbound interface is the interface between the
network application layer and the twin network layer. The
network application requirements are input from the twin
northbound interface to the twin network layer. The twin
northbound interface can support the rapid deployment of network
applications such as network operation and optimization, network
visualization, intent verification, and network automatic
driving with lower cost, higher efficiency, and less impact on
live network services. Therefore, the twin northbound interface
should have the characteristics of the following 4 aspects.Openness: The twin northbound interface must meet the
business requirements of different network applications and
can be input to the twin network layer, so it needs to have
good openness and compatibility;Scalability: There are a variety of network applications
in the network application layer, which will inevitably lead
to the generation of network applications. At the same time,
the continuous development of the network is bound to
introduce new network applications. With the upgrade of
network applications and the generation of new applications,
the twin northbound interface should be able to expand in
time to meet the needs of new network applications;Portability: There are twins with different sizes and
functions in the twin network layer. The same or similar
requirements of various applications in the network
application layer may be deployed on different twins.
Therefore, the twin northbound interface should be easily
transplanted and deployed on different twins;Flexible deployment: To reduce deployment time and cost,
twin northbound interfaces must be flexibly deployed.Twin Internal interfaceAs shown in the "three-layer, three-domain, double-closed
loop" of DTN architecture, the twin network layer contains three
key subsystems, namely, data sharing warehouse, service mapping
model and digital twin management, which is the most critical
part of the digital twin network. The internal interface of the
twin layer refers to the interface within and between the three
subsystems: data sharing warehouse, service mapping model and
digital Twin management. In order to support the functions of
the three subsystems in the twin network layer and the
interaction between the three subsystems, the internal interface
of the twin layer should have the following four functions.Unity: Each subsystem in the twin network layer should be
able to provide the same data format and data service for
other subsystems through the internal interface of the twin
layer, that is, the interface should have unity.Adaptability: The twin network layer must interact with
the network application layer and the physical network
layer, and should be well adapted to various network devices
and interfaces. Therefore, the internal interfaces of the
twin layer also need to be adaptive.Portability: The data model instances provided by the
service mapping model subsystem for different applications
may have a high degree of similarity. In order to improve
efficiency, the data model instances must be able to be
provided and deployed through different internal interfaces
of twin layers.Flexible and extensible: The twin network layer must be
able to verify different new network services. In order to
shorten the implementation time of functions, the
implementation of functions inside the twin layer should be
simplified as far as possible. Therefore, the internal
interface of the twin network layer must be flexible and
extensible.Twin southbound interfaceThe twin southbound interface is the interface between the
twin network layer and the physical entity network. Control
updates are delivered from the twin southbound interface to the
physical entity network, and various nes in the physical entity
network exchange network data and network control information
with the twin network layer through the twin southbound
interface. Therefore, the southbound twin interface should have
three functions.Information interaction capability: the twin southbound
interface should be able to collect the information of
different physical nes or network devices, and send the
configuration information of the twin network to the
physical network for execution, that is, it can realize the
information interaction between the twin network layer and
the physical entity network.Real-time: The realization of twin network configuration
verification and other functions must have certain
real-time, so the information collected and uploaded from
the physical entity network and the configuration
information sent from the twin network to the physical
network must have certain real-time, in order to meet the
real-time requirements of the digital twin network.Compatibility: Network devices and nes from different
manufacturers use different interfaces and protocols. The
southbound interfaces must be compatible to ensure the
reliability of information collection and configuration
delivery.TBDTBDThis document has no requests to IANA.