The Need for Distributed Cloud Networking
If Hot Standby disaster recovery solutions running in a traditional routed DCI network are still valid and are often part of the specifications of the enterprise, there are some applications and emerging services enabled with cloud computing that require an RTO and RPO of zero with a full transparent connectivity between the data centers.
These requirements have already been addressed, especially with the deployment of high-availability clusters stretched between multiple sites. However, the rapid evolution of business continuity for cloud computing requires us to offer more reliable and efficient DCI solutions to meet the flexibility and elasticity needs of the service cloud: dynamic automation and almost unlimited resources for the virtual server, network, and storage environment in a fully transparent fashion.
Disaster recovery is critical to cloud computing for two important reasons. First, physical data centers have “layer zero” physical limits and constraints such as rack space, power, and cooling capacity. Second, currently not many applications are written for the distributed cloud that accounts for the type of network transports and distances needed to exchange data between different locations.
DCI Solution with Resource Elasticity
To address these concerns, the type of network interconnection between the remote data centers that handles the cloud infrastructure needs to be as resilient as possible and must be able to support any new connections where resources may be used by different services. It should also be optimized to provide direct, immediate, and seamless access to the active resources dispersed at different remote sites.
The need for applications and services to communicate effectively and transparently across the WAN or metro network is critical for businesses and service providers using private, hybrid, or public clouds.
To support cloud services such as Infrastructure as a Service (IaaS), VDI/VXI, and UCaaS in a sturdy, resilient, and scalable network, it is also crucial to provide highly-available bandwidth with dynamic connectivity regardless of VM movement. This is true for the network layer as well as for the storage layer.
The latency related to the distances between data centers is another essential element that must be taken into account for the deployment of the DCI. Each service and function has its own criteria and constraints, so it relies on the application requiring the lowest latency to be used as a reference to determine the maximum distance between physical resources.
To better understand the evolution of DCI solutions, it is important to highlight one major difference when comparing the active/standby behavior between members of a high availability (HA) cluster and the live migration of VMs spread over multiple locations. Both software frameworks require LAN and SAN extension between locations.