I. Introduction
With the ever-increasing demand of cloud services, the data center network (DCN) has become an efficient and promising data processing infrastructure for cloud computing. As reported in the public data of Microsoft Azure [1], the demand and deployment size of the tenant is very bursty and unpredictable in terms of memory, cores, and bandwidth. One fundamental challenge of DCNs is to serve the varying needs of multi-tenant without requiring frequent provisioning changes. This paper proposes an elastic resource provisioning scheme to deal with the scaling without load redistribution during a run time. In order to simplify the description of the resource provisioning problem, we use virtual clusters to denote the requests of multi-tenant, and each virtual cluster is an abstraction of a set of virtual machines (VMs), which has the requirements on both computing and communication resources [3]. We use the notion of elasticity to measure the potential growth of multi-tenant in terms of computing and communication resources at the same time, which is defined as the degree of a system that is able to adapt to the workload changes by provisioning and releasing resources in an autonomic manner [5], [6], [8]. We consider the virtual clusters with hose model under constraints, and our objective is to maximize the elasticity while achieving rapid response to multi-tenants in the DCNs.