2. Introduction:
It is able to integrate SDN and NFV for efficient resource over‐reservation control to support
differentiated QoS over the 5G Internet without undue signalling and related processing overhead.
Network operator -1 is a mulitioperator network scenario encompassing network.
Network operator -2 is considered as a cloud of clouds.
The SDNC is responsible for granting or denying access to the network and the related resources in
such a way as to ensure that each admitted user receives the QoS contracted.
Also, the SDNC’s functions include, among others, traffic load balancing to avoid unnecessary
congestion occurrence inside the network while inter‐domain connections are performed according
to pre‐defined Service Level Agreements (SLAs) between the operators for scalability reasons.
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3. Introduction:
The SDNC is enabled for defining appropriate control policies and dictating the enforcement on the transport elements
(e.g. switches and routers)
Through appropriate signalling protocols (e.g. OpenFlow compliant protocol). This will ensure that every application is
effectively prevented from starving other applications of their resources inside the network.
Therefore, the SDNC embeds a set of control components such as, but not limited to:
(i) Control Information Repository (CIR) as being a database for maintaining network topological information and
users’ profiles.
(ii) Service Admission Control Policies (SACP), as the entity responsible for defining appropriate control policies and
managing access to the network resources.
(iii) Network Resource Provisioning(NRP), which can be used for advanced resource allocation. Further details on
these components in terms of functions and interactions are provided in the following subsections.
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5. Control Information Repository:
CIR by the is exploited SDNC to maintain the network topology and related link resource statistics, including
communication paths that may be created inside the network along with the IDs of the outgoing interfaces that
belong to the paths.
The CIR records the overall capacity of each network interface and the amount of bandwidth.
Active session information includes, but is not limited to, the QoS requirements of the session (e.g. bandwidth,
delay, jitter and packets loss).
The session ID, the IDs of the flows that make up the session, the ID of the CoS to which the session belongs, the
flows’ source and destination IDs (e.g. IP and Media Access Control – MAC – addresses).
The ports’ IDs. The users’ other profile information, such as billing and personalisation parameters, may also be
stored in the CIR.
In summary, the specific design and configurations of a SDNC would depend on the operators’ preferences, which
may vary from one operator to another.
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6. Service Admission Control Policies:
The SACP enables the SDNC to admit or deny service access to the network by dynamically taking into account
incoming service request QoS requirements (e.g. bandwidth).
It provides an interface to allow interactions with end‐users to receive requests on one hand, and with the network
nodes (e.g. routers) for sending control instructions to be enforced throughout the network, on the other.
Hence, upon admission, termination or readjustment of the QoS requirements of a session in a CoS on a
communication path, the session‐related information (e.g. resource usage) must be updated in the local CIR in a
real‐time manner.
The SACP is able to admit, terminate or readjust the QoS demands without undue signalling overhead or waste of
resources.
Since the network resource utilisation statistics are maintained in a real‐time manner in the CIR, the information
can be exploited to improve traffic load‐balancing functions in a flexible way without undesired path‐probing and
the related signalling overhead.
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7. Network Resource Provisioning:
The main role of the NRP component is to define the amount of resources to be over‐reserved and the
parameters, such as reservation thresholds, to be configured for each CoS on each interface inside the network
according to the local control policies.
This component must be intelligent enough to allow the integration of existing over‐reservation algorithms and
policies, as in including future algorithms.
This is important since the NRP is invoked dynamically by the admission control functions so that reservation
parameters can be readjusted upon need to prevent ineffective use of resources while reducing signalling
frequency.
It turns out that this component can also be used to create and manage deterministic communication paths
inside the network (e.g. Label Switching Paths as in Multi‐protocol Label Switching – MPLS).
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8. Network Configurations:
The SDNC is able to discover the network topology dynamically as new nodes boot up inside the network. One
may use existing topology discovery mechanisms by importing the information from link‐state routing
protocols.
Hence, by taking the network topology and appropriate algorithm as inputs, the SDNC is able to compute all
possible paths, especially the edge‐to‐edge paths inside the core network under its control.
A combination of the paths may lead to all possible branched routes and the best paths can be filtered, for
example, based on the number of hops or bottleneck bandwidth.
It is worth recalling that the use of deterministic paths is very important to improve network resource control.
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10. To facilitate the understanding, let’s suppose that User A wants to enjoy a 3D video service from the provider of DC B
(Data Centre B) in the cloud. Hence, the user issues a service request, which is directed to the SDNC via a gateway,
BR1 (step 1).
The service request contains the user’s QoS requirements (e.g. bandwidth) and the related traffic characteristics (e.g.
codec).
Hence, based on the information received, SDNC I performs the admission control according to the pre‐defined local
control policies and books the best path with sufficient available bandwidth for connecting the gateway BR1 and
egress BR3 towards DC B.
It is therefore very important to note that the SDNC is able to do so without any path probing or extra QoS signalling
into the network since we assume that it integrates the resource over‐reservation solution .
In case these operations are successful, the server redirects the request to SDNC II (operator B’s network), as being
the next domain on the end‐to‐end path towards the DC B.
When SDNC II receives the request, it also books the best path (BR5 to BR8) without any extra signalling overhead and
checks the requested service availability in the DC B. Then, upon receiving a successful response from the DC B, SDNC
II enforces the booked path by properly configuring the border routers on the path (BR5 and BR8).
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11. Examples of the configurations include the selected path’s multicast group (in multicast‐enabled domain) or MPLS
label (in MPLS domain), and traffic conditioning parameters (e.g. classification, shaping and policing).
This will ensure that incoming media packets will be correctly encapsulated at the ingress edge routers to follow the
desired paths, so they enjoy the QoS reserved for them. The packets are decapsulated at the relevant egress edge
routers for delivery to the end‐user or the following domain.
As we explained in 2.6.3, only the BRs are configured since it is assumed that the over‐reserved resources are still
available on the core/interior nodes on the path. As we detailed earlier, the core nodes are signalled to reconfigure
the reservation parameters only after the over‐reserved resource has exhausted and is not sufficient for the
incoming request.
In this way, not only can the signalling frequency be significantly reduced, but also the session setup time will be
reduced. Afterwards, SDNC II replies to SDNC I and the latter also enforces the path that was booked for the service
(see step 7).
Finally, SDNC I notifies user A about the operations success (see step 8). At the same time, SDNC I sends an
Acknowledgement (ACK) message to SDNC II, whose message is forwarded to DC B (see step 9) to trigger the media
streaming..
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