Page 174 - 5G Basics - Core Network Aspects

1 Core network aspects

7.1 SDN application layer

The SDN-AL enables a service-aware behaviour of the underlying network in a programmatic manner. It is
composed of the application layer management support and orchestration (AL-MSO) functional component
and multiple SDN application functional components (see Figure 7-2).

The SDN-AL interacts with the SDN-CL via the application control interface (ACI) reference point, and interacts
with the MMF via the MMF application layer (MMFA) reference point.

Figure 7-2 – SDN-AL functional components
7.1.1 SDN application functional component

SDN application functional components interact with the SDN-CL via the ACI reference point, in order for the
SDN-CL to automatically customize the behaviour and the properties of network resources. An SDN
application functional component uses the abstracted view and status of the network provided by the SDN-
CL by means of information and data models exposed through the ACI reference point. Depending on the
SDN use cases (e.g., intra- or inter-data centres, mobile networks, access networks), interfaces exposed by
the SDN-CL at the ACI reference point can differ in nature.
NOTE – This Recommendation also uses the term "SDN application", an application that controls and manages network
resources (e.g., for application specific routing purposes) by using capabilities provided through the ACI reference point.
An SDN application functional component as described in this clause consists of the necessary software required to
implement an SDN application.
7.1.2 AL management support and orchestration functional component

The AL-MSO functional component orchestrates SDN applications (including applications composed of
multiple applications) with the support of MMF. The AL-MSO functional component may involve the SDN-CL
and/or MMF orchestration for the deployment of appropriate SDN-CL and MMF functional components
respectively.
The AL-MSO functional component includes the following:

– SDN applications code repository management;
– SDN applications' lifecycle management (creation, modification, and deletion);
– performance monitoring of SDN applications to meet SLA requirements;
– detection, isolation, and correction of SDN applications' faults, and;
– security related capabilities (including for authentication and identity management purposes) of
SDN applications provided by network operators and/or third parties.
SDN applications code repository management provides optimal usage of the repository which stores various
SDN application codes and ensures integrity and authenticity of SDN application codes. It also provides
efficient search capability of the stored SDN application codes. AL-MSO security management of 3rd party
SDN applications protects from anomalous registration and usage of 3rd party SDN applications.

The AL-MSO functional component provides capabilities for provisioning SDN-AL resources, i.e., resources
that are used to run SDN applications, based on the requests received from MMF. The AL-MSO functional
component coordinates provisioning of SDN-AL resources and network resources in the SDN-RL in a cross-
layer manner and also performs atomic transactions to ensure the integrity of the requested provisioning.
The AL-MSO functional component provides capabilities for managing the capacity and performance related

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