Page 268 - Cloud computing: From paradigm to operation

1 Framework and requirements for cloud computing

5 Conventions

In this Recommendation:
The keywords "is required" indicate a requirement which must be strictly followed and from which no
deviation is permitted if conformance to this document is to be claimed.
The keywords "is prohibited" indicate a requirement which must be strictly followed and from which no
deviation is permitted if conformance to this document 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.

6 Overview of cloud infrastructure

In this Recommendation, cloud infrastructure includes processing, storage, networking and other hardware
resources as well as software assets.

Abstraction and control of physical resources are essential means to achieve the on-demand and elastic
characteristics of cloud infrastructure. In this way, physical resources can be abstracted into virtual machines
(VMs), virtual storages and virtual networks. The abstracted resources are controlled to meet cloud service
customers' (CSCs) needs.
The main characteristics of cloud infrastructure are:
– Network centric: The cloud infrastructure consists of distributed resources including processing,
storage and other hardware resources that are connected through the networks;
– On-demand resource provisioning: The cloud infrastructure dynamically provides resources
according to CSCs' needs;
– Elasticity: The cloud infrastructure is capable of expanding or reducing its resources to
accommodate the current workloads;

– High availability: The cloud infrastructure is capable of providing required resources under the
conditions stated in the service level agreement (SLA);
– Resources abstraction: The underlying resources of cloud infrastructure (processing, storage,
networking, etc.) are invisible to the CSCs.
NOTE – For high level cloud computing requirements, please refer to [ITU-T Y.3501].

7 Requirements for processing resources
Processing resources are used to provide essential capabilities for cloud services and to support other system
capabilities, such as resource abstraction and control, management, security and monitoring.
The basic unit of allocation and scheduling of processing resources is a computing machine. A computing
machine can be physical or virtual. The capability of a computing machine is typically expressed in terms of
configuration, availability, scalability, manageability and energy consumption.

7.1 Physical machine requirements
The physical machine requirements include:
• It is recommended to support hardware resource virtualization.
• It is recommended to support horizontal scalability (e.g., adding more computing machines) and
vertical scalability (e.g., adding more resources with a computing machine).
• It is recommended to use power optimization solutions to reduce energy consumption.

260