Page 652 - Cloud computing: From paradigm to operation

3 XaaS

OVF Open Virtualization Format

QoS Quality of Service
SLA Service Level Agreement

UML Unified Modelling Language
VLAN Virtual Local Area Network

VM Virtual Machine

5 Conventions

The keywords "is required to" indicate a requirement which must be strictly followed and from which no
deviation is permitted if conformance to this Recommendation is to be claimed.
The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely
required. Thus this requirement need not be present to claim conformance.
The keywords "can optionally" indicate an optional requirement which is permissible, without implying any
sense of being recommended. This term is not intended to imply that the vendor's implementation must
provide the option and the feature can be optionally enabled by the network operator/service provider.
Rather, it means the vendor may optionally provide the feature and still claim conformance with the
specification.
In the body of this Recommendation and its annexes, the words shall, shall not, should, and may sometimes
appear, in which case they are to be interpreted, respectively, as is required to, is prohibited from, is
recommended, and can optionally. The appearance of such phrases or keywords in an appendix or in material
explicitly marked as informative are to be interpreted as having no normative intent.

6 General description

Infrastructure as a Service (IaaS) is one of the representative categories of cloud services, in which the cloud
capabilities type provided to the cloud service customer (CSC) is an infrastructure capabilities type. IaaS
allows the CSC to use cloud infrastructure resources (processing, storage or networking). Use of cloud
infrastructure resources is supported by service functions, which can include the relevant operations.
IaaS provides to the CSC the following service functions:
– computing service functions allow the CSC to provision and use processing resources. CSC can
perform operations relevant to processing resources including machine (physical or virtual machine)
lifecycle operations and functions such as virtual machine (VM) migration, backup, snapshot, clone
and reservation;

– storage service functions allow the CSC to use storage resources. The CSC can perform operations
relevant to storage resources including lifecycle operations and functions such as snapshot, backup,
input/output (I/O) performance, load balance and reservation;
– network service functions allow the CSC to use networking resources. The CSC can integrate
infrastructure resources using network relevant functions such as IP address, network isolation (e.g.,
virtual local area network (VLAN)), virtual networking (e.g., virtual switch), load balance and firewall.

The high level concept of IaaS using the layering framework defined in [ITU-T Y.3502] is illustrated in
Figure 6-1.

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