Identity: A data center network fabric to enable co-existence of identical addresses

Seamless virtual machine (VM) mobility within and across data centers brings its own set of problems. One of these problems is enabling co-existence of identical or overlapping layer-2 and layer-3 addresses in a single data center network. The motivation for this problem comes from a number of compelling scenarios. These include the need to backup and restore or replicate multi-tier applications that comprise of multiple VMs from one data center to another or within the same data center. This requires significant network reconfiguration costs as IP addresses of replicated VMs may clash with other existing IP addresses in the data center or with other replicas of the same VMs. Similarly, when multiple data centers need to be consolidated through a single data center interconnect, their address ranges may overlap. Lastly, cloud providers need to ensure that various customers can backup and restore their VMs which can have potentially conflicting addresses with other customers' VMs without requiring time consuming network reconfiguration efforts. In this paper, we present Identity - a data center network fabric that enables co-existence of hosts or VMs with identical layer 2 and layer 3 addresses. We use pseudo addresses to uniquely identify each host or VM and employ address resolution and duplicate detection techniques to enable co-existence of hosts and VMs with identical addresses. We leverage the centralized programmable control plane offered by OpenFlow and present the design and implementation of our scheme in Mininet. We provide an experimental evaluation of our scheme and validate that its average latency and throughput performance is as good as a default setup.