| Internet-Draft | Network Working Group | March 2023 |
| Chen, et al. | Expires 9 September 2023 | [Page] |
The 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 [RFC2119].¶
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As defined in the[I-D.irtf-nmrg-network-digital-twin-arch] , 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 technology¶
Based 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.¶
+---------------------------------------------------------------------+
| |
| Network Application Layer |
| |
+-------^-------------------------^----------------------^------------+
| | |
Twin
| | | Northbound
| | | Interface
+-------v-------------------------v----------------------v-----------+
| Twin Network Layer |
| |
| +------------+ +----------+ +---------------+ |
| | data | | service | | digital | |
| | sharing <-----------> mapping <----------> twin | |
| | warehouse | Twin | model | | management | |
| +------------+ Internal +----------+ +---------------+ |
| Interface |
+--------^------------------------^-----------------------^----------+
| | | Twin
| | | Southbound
| | | Interface
+--------v------------------------v-----------------------v-----------+
| |
| Physical Network Layer |
| |
+---------------------------------------------------------------------+
Twin northbound interface¶
The 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.¶
Twin Internal interface¶
As 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.¶
Twin southbound interface¶
The 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.¶
With the development of communication networks, many North-South and intra-network communication protocols have been formed in the network, such as RESTCONFRFC 8527 [RFC8527], NETCONFRFC 8526 [RFC8526], OpenFlow, XMPPRFC 7622 [RFC7622], East-West Bridge, etc.. Because different communication protocols have different characteristics, the existing protocols are suitable for different twin network interfaces. In this draft, we attempt to give some suggestions about the applicability of some existing general protocols suitable for DTN construction.¶
This document has no requests to IANA.¶