Page 295 - Cloud computing: From paradigm to operation

Framework and requirements for cloud computing 1

In Figure 8-1, intra-cloud service and resource handling allows a CSP (A or B) to manage its own resources
including underlying physical resources and abstracted resources. Inter-cloud service and resource handling
allows a CSP to negotiate for the use of peer CSPs' abstracted resources provided as cloud services.
For example, when CSP A decides to use resources from CSP B, its intra-cloud service and resource handling
will interact with its inter-cloud service and resource handling, which will then interact with CSP B. When the
inter-cloud service and resource handling of CSP B receives the request from CSP A, the request will be
relayed towards its own intra-cloud service and resource handling in order for CSP B to decide whether to
provide the service and associated abstracted resources to the CSP A.

8.2 Overview of inter-cloud federation

8.2.1 Introduction
In the inter-cloud federation pattern, a number of CSPs provide services to CSCs. When needed (e.g., in the
event of a serious shortage in resource pool), CSPs within the inter-cloud federation utilize other CSPs'
resources to provide services to their customers.
Figure 8-2 illustrates the inter-cloud federation pattern.

Inter-cloud federation

CSP B
CSC 1 Service X

CSP A CSP C
Service Y
CSC 2

Service Z
CSC 3 CSP E CSP D

Y.3511(14)_F8-2

Figure 8-2 – Inter-cloud federation

As shown in Figure 8-2, CSC 1 and CSC 2 use services X and Y provided by CSP A, but the resources used for
services X and Y may actually be provided by CSPs B, C or E.

8.2.2 Primary CSP and secondary CSP
In an inter-cloud federation, two or more CSPs interact to provide cloud services to CSCs. The CSP that is
responsible for providing the services to a given CSC is called the primary CSP while the peer CSPs in the inter-
cloud federation offering their own resources as services to the primary CSP are called secondary CSPs.

When needed, the primary CSP will make request in order to utilize the resources of secondary CSPs. The
primary CSP determines which secondary CSPs will actually provide such resources (e.g., in terms of
processing power, storage and networks) to the CSC. In some cases, the primary CSP may provide none of its
own resources and will have to obtain all resources required for the support of services from secondary CSPs.
The roles of primary CSP and secondary CSP depend on the individual service. For example, in Figures 8-3
and 8-4, CSP A is the primary CSP and CSPs B, C and E are secondary CSPs for services X and Y. For service Z,
CSP E is the primary CSP and CSPs A and D are secondary CSPs.

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