Page 637 - Cloud computing: From paradigm to operation

XaaS 3

existing VPN, there is a need to provision a new subnet in the CSP's data centre and to set
up a new virtual routing and forwarding (VRF) in its edge router. The migration of the
corresponding subnet from the CSC's data centre to the CSP's data centre and the subnet
removal from the CSC's data centre needs to be announced to the remaining edge routers.
The concrete procedure is shown in the following figure.
1. Processing resources and the corresponding subnet migrate from the CSC's data centre
to the CSP's data centre.
2. New VRF is configured in the edge router of the CSP's data centre.
3. The removal of the CSC's subnet is announced through MP-BGP update to all VPN sites.
4. CSP's new subnet is announced through MP-BGP update to all VPN sites.
Service continuity needs to be ensured during the whole migration and reconfiguration
procedure. However, the existing VPN is a black box from the CSC's perspective, and as
such it can't be provisioned and reconfigured by the CSC. In addition, the current VPN
technology cannot support the dynamic addition and reduction of the VPN sites and
bandwidth capacity.

Roles CSC, CSP
Figure
(optional)

Pre-conditions
(optional)
Post-conditions
(optional)
Derived – Elastic network reconfiguration (refer to clause 9.5)
requirements

II.4.2.3 NaaS connectivity use case for BoD service

Title NaaS connectivity use case for BoD service
Description In this scenario CSU access to cloud computing service offered by XaaS CSP is considered
(e.g., virtual desktop infrastructure (VDI), video streaming). CSU accesses the service from a
fixed location e.g., using a company local area network (LAN) or from mobile location e.g.,
mobile terminal. The XaaS CSP serves the services on the basis of own data centres and has
no impact on the performance of particular connectivity between end users and the data
centre where the service is hosted. From the perspective of CSU, quality of experience
(QoE) of the service is dependent on a combination of data centre and network
performance. The XaaS CSP is able to guarantee certain service quality limited to its own
data centre. This quality could be downgraded on network performance on the connection

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