Page 312 - Cloud computing: From paradigm to operation
P. 312

1                                    Framework and requirements for cloud computing




                                      Table I.5 – Inter-cloud use case: Service continuity

                                                         Use case
             Use case title                Inter-cloud use case: Service continuity
             Relevant roles                CSP and CSC
             Use case description          –  The cloud service offering continues through the collaboration with other
                                              CSPs, even when the original CSP terminates its business.
                                           –  Available resources in the CSPs other than the service-terminating CSP are
                                              discovered and reserved in advance.
                                           –  Network connections among the interworking CSPs are established or
                                              reconfigured. Then service-related data including user identifier (ID), user
                                              data and application data are transferred from the original CSP to the new
                                              CSPs.
                                           –  Access from CSCs is appropriately changed to the interworking CSPs so that
                                              the same service is continuously offered.
                                           –  If the capabilities (VM and applications) at the original CSP migrate to other
                                              CSPs, the CSC, who keeps the same user ID, can continuously access the
                                              service at the same level of performance as before.
             Information flow              –  The relevant CSPs are supposed to join a common trusted alliance in
                                              advance and set up the service level agreements (SLAs).
                                           –  The terminating CSP inquires about the resource availability of other CSPs
                                              in the alliance and requests a reservation of the available resources to
                                              continue the services.
                                           –  The cloud resource management (e.g., CRUD: create, read, update and
                                              delete) are operated across multiple CSPs. The management is to enable
                                              leasing of the cloud resources from different CSPs in the federation.
             High-level figure describing the   Pre-processes
                                                • CSPs form a group with service level agreement (i.e., policy negotiation).
             use case                           • P-CSP replicates its data to other S-CSPs in advance.
                                                                           3. The P-CSP chooses S-CSPs and reserves the resources.
                                                         2. The P-CSP initiates  3a. When some CSCs are in service, the P-CSP performs
                                                         service closure.  migration to continue the service to the CSCs.
                                                                           3b. When no CSC is in service, the S-CSP invokes
                                                                           application to offer the same service.
                                                 1. A CSC accesses  Primary-
                                                 P-CSP services.    CSP                   n
                                                                        o
                                                                                     n
                                                CSC                                    S-CSP
                                                                         Secondary-  S-CSP
                                                                           CSP             Group
                                                 4. P-CSP changes the
                                                 CSC access to the S-CSP.
                                                NOTE – When all services and their users are moved to other S-CSPs, P-CSP will close the service.
                                                                                                 Y.3511(14)_FI.Tab5
             Derived requirements for cloud   The system is required to support:
             capability                    –  Policy negotiation including SLA management among the multiple CSPs
                                              within a pre-established group (federation);
                                           –  Discovery, reservation, use and release of the cloud resources in a dynamic
                                              manner (i.e., not relying on the pre-configuration) across the multiple CSPs
                                              within the federation;
                                           –  Capability migration (e.g., VM and applications) among multiple CSPs within
                                              the federation;
                                           –  Alteration (i.e., switchover) of the CSC access, in a dynamic manner (i.e., not
                                              relying on the pre-configuration), from one CSP to another CSP within the
                                              federation;
                                           –  Exchange of authentication information about CSC (user/enterprise)
                                              authentication status among the multiple CSPs within the federation.





            304
   307   308   309   310   311   312   313   314   315   316   317