Fault-tolerance, survivability and resiliency in wide area networks have long been prominent research topics. With the popularity of the cloud service model and the novel software defined networking (SDN) paradigm, there is renewed interest in failure protection and restoration in network service provisioning. In this work, we propose a novel protection and restoration based virtual network management scheme to enhance fault tolerance in infrastructure-as-a-service, deployed over networked cloud infrastructure. The networked cloud infrastructure is composed of multiple geographically distributed datacenters that are interconnected with SDN. Both compute and network resources are allocated by formulating the virtual network embedding problem as an integer linear program. A shared backup virtual link protection mechanism and a reactive traffic engineering network failure restoration algorithm are proposed and integrated with the framework to provide recovery from unexpected link failures. We implemented the framework on an emulated SDN testbed and evaluated the performances of the algorithms during single and multiple link failures. Experimental results demonstrate trade-offs of the proposed approaches and their applicability in different application scenarios.