Page 623 - Cloud computing: From paradigm to operation

XaaS 3

• On-demand reconfiguration

Cloud computing system allows for dynamic computing and storage resources reconfiguration or
migration to meet the changing requirements. It is desirable that networks provide on-demand
reconfiguration to satisfy the requirements of cloud services, e.g., change of bandwidth,
modification of network topology or addition of new network elements.

6.2 High-level concept of NaaS
As defined in [ITU-T Y.3500], Network as a Service (NaaS) is a category of cloud services in which the capability
provided to the cloud service customer (CSC) is transport connectivity and related network capabilities in
order to solve the challenges mentioned above. NaaS services are divided into NaaS application service, NaaS
platform service and NaaS connectivity service. In particular, NaaS connectivity service is an "infrastructure
capabilities type" service limited to networking resources.
The high-level concept of NaaS using the layering framework defined in [ITU-T Y.3502] is illustrated on
Figure 6-1.
NaaS can provide any of the three cloud capabilities identified in [ITU-T Y.3500] as follows:

• NaaS application: application capabilities type of service where NaaS CSC can use network
applications provided by NaaS cloud service provider (CSP). These network applications are
considered and used as a virtual network functions provided by NaaS CSP. This includes any network
function for either fixed or mobile or both core and access as well as for control and forwarding
planes network elements. Examples of NaaS applications include virtual router, virtual content
delivery network (vCDN), virtualised evolved packet core (vEPC) and virtual firewall (vFW).
In this category, CSP offers a set of interfaces for network functionalities.
• NaaS platform: platform capabilities type of service where NaaS CSC can use the network platform
provided by NaaS CSP. The NaaS platform offers one or more software execution environments and
one or more programming languages to deploy, manage and run customer-created or customer-
acquired network applications. Such network applications can be created or acquired by CSC as self-
implemented network services. Network applications can implement various network
functionalities or services, e.g., router, firewall, load balancer, as well as groups of network
functionalities. Groups of network applications and functionalities can form an integrated network
solution.
In this category, CSP offers a programmable environment for network functionalities that can be
employed by cloud service customer or cloud service partner software.
• NaaS connectivity: infrastructure capabilities type of service where NaaS CSC can provision and use
networking connectivity resources provided by NaaS CSP. This includes for example flexible and
extended virtual private network (VPN), bandwidth on demand (BoD), etc. NaaS can provide basic
networking functionalities such as connectivity, using whatever physical, logical or virtual
networking capabilities the CSP chooses to offer. There is often a desire to offer more than IP
networking. For example, a CSC may wish for elastic, on-demand control of optical networks, or
even for access to dark fibre using photonic switching.
In this category, CSP offers network connections between two or more endpoints, which may
include additional network functionalities.
NOTE 1 – The creation, control, management and removal of NaaS connectivity is performed as a cloud
service.
NOTE 2 – NaaS typically provides "bearer" connectivity of raw data without regard to the type of data carried
between endpoints. Services that are specific to a type of carried data, such as telephony, voice over IP (VoIP),
video conferencing, and instant messaging, are typically categorised as Communications as a Service (CaaS).
NOTE 3 – The endpoints of NaaS connectivity can reside either within the NaaS service interface itself, in
another cloud service, in a non-cloud service or at a traditional network endpoint.

NaaS services can be utilized by both cloud and non-cloud services.

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