Page 678 - Cloud computing: From paradigm to operation

3 XaaS

Resources offered by the NaaS CSP to the NaaS CSC depend on the type of NaaS service
(e.g., NaaS connectivity, NaaS applications as described in [ITU-T Y.3512]) being provided by the NaaS CSP.
These resources can be negotiated by the NaaS CSC with the NaaS CSP through the use of the service interface
provided by the NaaS CSP. For example, subject of such negotiation can cover connectivity parameters for a
NaaS connectivity service provided by the NaaS CSP.
Service requests made by the NaaS CSC via the service interface will trigger interactions with other NaaS
CSP's functionalities such as evolved real-time OSS functionalities (see clause 7.7) and NaaS CSP's resource
functionalities (e.g., network elements), for example for instantiating network services, network functions,
for allocating cloud computing resources and network connectivity resources in NaaS CSP's infrastructure.
The service interface can also allow the NaaS CSC to instantiate and operate flexible, scalable and functionally
expandable virtualized networks as well as provide unified control and management functionalities to the
NaaS CSC for changing, moving, or removing resources associated to such virtualized networks being offered
by the NaaS CSP.

6.3 Virtualization of network functions

As described in [ITU-T Y.3512], NaaS services include:
– NaaS application and NaaS platform services such as virtual IP multimedia subsystem (vIMS), virtual
evolved packet core (vEPC) and virtual content delivery network (vCDN);
– NaaS connectivity services such as virtual private network (VPN) services and bandwidth on demand.
These NaaS services rely on network services (see clause 3.2.3) and network functions (see clause 3.2.2)
provided on-demand by the NaaS CSP to the NaaS CSC. When deployable as software by the NaaS CSP,
network functions are known as virtualized network functions (VNFs) (see clause 3.2.5). Examples of such
VNFs are virtualized control network entities (see [ITU-T Y.2320]). When implemented via a tightly coupled
software and hardware system, network functions are considered as physical network functions (PNFs)
(see clause 3.2.4).
Figure 6-2 provides a representation of aspects that need to be controlled and managed by NaaS CSP.

Figure 6-2 – Aspects managed by NaaS CSP

NaaS services offered to NaaS CSCs are based on NSs and network functions (NFs) that need to be managed
by the NaaS CSP. Although not illustrated in Figure 6-2, connectivity between NFs needs also to be managed
by the NaaS CSP, including connectivity between NFs in a given NS and connectivity between different NSs.

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