Realization of Composite IETF Network Slices

A network slice offers connectivity services to a network slice customer with specific Service Level Objectives (SLOs) and Service Level Expectations (SLEs) over a common underlay network. RFC 9543 describes a framework for network slices built in networks that use IETF technologies. As part of that framework, the Network Resource Partition (NRP) is introduced as a collection of network resources that are allocated from the underlay network to carry a specific set of network slice service traffic and meet specific SLOs and SLEs. In some network scenarios, network slices using IETF technologies may span multiple network domains, and they may be composed hierarchically, which means a network slice itself may be further sliced. In the context of 5G, a 5G end-to-end network slice consists of three different types of network technology segments: Radio Access Network (RAN), Transport Network (TN) and Core Network (CN). The transport segments of the 5G end-to-end network slice can be provided using network slices described in RFC 9543. This document first describes the possible use cases of composite network slices built in networks that use IETF network technologies, then it provides considerations about the realization of composite network slices. For the multi-domain network slices, an Inter-Domain Network Resource Partition Identifier (Inter-domain NRP ID) may be introduced. For hierarchical network slices, the structure of the NRP ID is discussed. And for the interaction between IETF network slices with 5G network slices, the identifiers of the 5G network slices may be introduced into IETF networks. These network slice- related identifiers may be used in the data plane, control plane and management plane of the network for the instantiation and management of composite network slices. This document also describes the management considerations of composite network slices.