Page 154 - 5G Basics - Core Network Aspects

1 Core network aspects

11.5 Interfaces

There are two interfaces in the high-level architecture of SDN: the application-control interface and the
resource-control interface. They provide access to the SDN controllers and network resources, allowing for
programmable control of network resources.

The details of each interface are as follows:
– Resource-control interface
The resource-control interface is used for interactions between the SDN control layer and the
resource layer. Information exchanged through these interactions include controlling information
provided by the SDN control layer to the resource layer (e.g., for configuring a network resource or
providing policies) as well as the information that pertains to the (unsolicited) notifications sent by
the resource layer whenever the network topology changes, congestion is detected, etc. Such
notification information also includes data that are meant to assess the conformance of what has
been delivered against what has been negotiated (hence the notion of service fulfilment and
assurance). This interface provides high-level accesses to the network resources regardless of their
respective technology.

– Application-control interface
The application-control interface is used for interactions between the application layer and the SDN
control layer. The application-control interface can be used by the application layer to feed the SDN
control layer information that will contribute to the decision-making process in terms of dynamic
resource allocation or policy enforcement, for example. The SDN control layer can also expose the
information and data models that reflect the resource abstraction to the application layer through
this interface.

12 Environmental considerations

SDN is meant to facilitate self-adaptability, so that resource availability and usage efficiency can be improved.
This is likely to contribute to the optimization of resource usage and therefore reduced energy consumption.

SDN relocates the control of network resources to a logically centralized SDN controller. This may contribute
to simplify the design of network elements, thus power consumption is expected to decrease. However, the
function that is logically centralized may become complicated, thus its power consumption may increase.

13 Security considerations

The introduction of a high level of automation in the overall service delivery procedure by means of SDN
techniques inevitably raises security challenges. In particular, access to network resources by applications
must be granted in order to protect the networking infrastructure and its components from a denial of service
attack that may jeopardize the overall robustness, quality and reliability of the SDN architecture, or the
services that it delivers.
SDN provides new possibilities to combat security breaches. The affected resources may be easily and quickly
isolated, malicious traffic may be safely terminated, sensitive flows can be identified and separately
transferred in a more secure manner, e.g., with dedicated equipment and security protocols. All these
processes may be automated due to SDN for improved availability. Moreover, a logically centralized control
of SDN enables operators and/or entities to have a broader and/or a global view of the current status of
networks, which makes security operations easier and more efficient.

On the other hand, SDN may aggravate the damage of security breaches, misconfiguration, privacy
infringement and other incidents. Properties that were traditionally implemented in hardware and
impossible to change can now be modified, misconfigured or can function improperly. Such damage can
expand quickly as responses of various software programs and human operation may be too slow for
appropriate reaction. It is therefore necessary to enhance monitoring capability and automated operations.
More careful checking of e.g., policy configuration, becomes necessary. Moreover, a logically centralized
controller can be a single point of failure, and can be a target of malicious attacks, thus special attention is
required.

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