Page 164 - 5G Basics - Core Network Aspects

1 Core network aspects

7.2 SDN application layer

The SDN application layer executes SDN applications and enables network resources to behave in a service-
aware, programmatic manner.
The functional requirements for the SDN application layer are as follows:
– It is required to create and apply the application-specific programs to the SDN resource layer by
interacting with the SDN control layer.
– It is required to support multiple applications at the same time.
– It is required to notify network events from the SDN control layer to the corresponding SDN
application.
NOTE – Network events are information of network resources that are necessary for SDN applications to run in an
appropriate manner, e.g., start/end of an activity, failure, performance degradation to be handled by SDN applications.
– It is required to orchestrate multiple SDN applications within the SDN application layer.
– It is required to categorize SDN applications and combine multiple applications into an integrated
SDN application.

7.3 SDN control layer

The SDN control layer includes application support, orchestration, and abstraction functions.
Orchestration provides the coordination of requests from the SDN application layer and automated control
of network resources, such as the management of physical and virtual network topologies, network resources
and traffic.
Abstraction provides abstracted views of the property and behaviour of underlying network resources, in
order to support the management and orchestration of physical and virtual network resources.
The functional requirements for the SDN control layer are as follows:

– It is required to provide orchestration, abstraction and programmability of the network resources.
NOTE – Programmability provides the ability to control or configure the network resources by introducing a high level
of automation. Behaviour of network resources can be programmed by SDN applications for network control and
management functionality.
– It is required to discover underlying network topology to see how network resources (e.g., SDN-
enabled switches) connect to each other.

– It is required to collect and maintain network information about the capability of network resources
and network-wide information, including the status of forwarding tables, routing policies and
network topologies.
– It is required to back up network information in case of failures.
– It is required to build and update forwarding paths constituted by network resources, such as
switches, routers and data processing entities.
– It is required to provide an abstracted view of different network solutions (e.g., Packet Transport
Network, Optical Transport Network) to SDN applications.
– It is required to expose network configurations (e.g., routing policies) to the SDN application layer.
– It is required to maintain a set of lists of data processing entities (e.g., firewall, transcoding)
categorized by their capabilities.
– It is recommended to create and maintain mapping information between SDN applications and
network resources.

7.4 SDN resource layer
The SDN resource layer provides control support, data transport and processing functions.

The functional requirements for the SDN resource layer are as follows:

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