Achieving the high level of flexibility, resource availability, and transparency necessary for distributed cloud services DCI requires four components:
- Routing Network: The routing network offers the traditional interconnection between remote sites and gives end-users access to the services supported by the cloud. This component is improved using GSLB-based services such as DNS, HTTP redirection, dynamic host routes, and LISP.
- LAN Extension: The technical solution for extending the LAN between two or more sites using dedicated fibers or Layer 2 over Layer 3 transport mechanisms for long distances.
- Storage Services: The storage services used to extend access between SAN resources. SANs are highly sensitive to latency and therefore impose the maximum distances supported for the service cloud. It is preferable to use an Active/Active replication model to reduce the latency to its minimum value.
- Path Optimization Solution: The path optimization solution improves the server-to-server traffic as well as the ingress and the egress workflows.
Unlike the classical data center interconnection solutions required for geo-clusters that can be stretched over unlimited distances, DA and live migration for the service cloud require that active sessions remain stateful. As a result, maintaining full transparency and service continuity with negligible delay requires that the extension of the LAN and the SAN be contained within metro distances.
Enterprises and service providers may still have strong requirements to extend the LAN and SAN over very long distances, such as the need for operation cost containment or DP in stateless mode. These needs can be addressed if interrupting (even for a short period of time) and restarting sessions after workloads are migrated is acceptable to the system managers. Those requirements can be achieved using tools such as Site Recovery Manager from VMware© or an active-active storage solution such as EMC VPLEX Geo© for more generic system migration.