Today’s data centers host Server, Network, and Storage equipment, or the hardware resources needed to deploy various customer applications on these data centers. Customer applications are typically multi-tier – web, application, and database – with their own set of networking requirements. In addition, data centers utilize server and storage virtualization technologies.
Since virtualization offers the capabilities to create, snapshot, replicate, and delete resources on demand, provisioning of customer workloads for server and storage requirements is carried out instantly once a customer’s request is received. However, to satisfy networking requirements such as security policies and load balancers for customer workloads, data center providers either use manual provisioning or develop automation scripts to provision custom networking requirements. Whenever any movement in workload is required to move from a server to a new server or there is a need to change connectivity between workloads, data center providers provision the networking equipment manually. For large-scale data centers which are frequently required to efficiently utilize server and storage resources and provide enhanced customer experiences, manual provisioning of networking policies has always been a bottleneck, as networking has been very static and could not satisfy the dynamic changes as required by workloads and applications, until now.
Recent disruptive changes in networking virtualization technologies have helped to remove this barrier and provide more agility so that networking can now respond instantly to dynamic changes required by workloads/applications. Such newer data centers that have fully embraced virtualization technologies across server, storage, and network infrastructures and services are known as Software-Defined Data Centers (SDDCs).
Traditional data centers typically deploy a 3-tier networking architecture with Access/Distribution/Core switches, which is particularly suitable for north-south traffic between client and server. However, recent multi-tier web design architectures and new trends in big data gave rise to significant east-west traffic growth compared to client-server (north-south) traffic. This required a relook at data center designs to support next-generation application architectures that require non-blocking, high-bandwidth, loss-less transport, deterministic latency, unlimited workload and mobility, and simplified provisioning and management from underlying networks.
In the wake of the above development, Clos networks that were popular in the 1950s for telephone switching are becoming popular again as they support the requirements for next-generation application architectures. Clos networks are built using multi-stage switching fabrics with low-cost switches (also referred to as Leaf-Spine fabric). End servers are connected to Leaf switches and Leaf switches are connected upwards towards all the Spine switches above it as shown below. Leaf-Spine fabric helps newer data centers meet high-demand traffic from today’s applications/workloads.
Moreover, to address the required agility demanded by workloads or applications, traditional networking designs are being revamped to Software Defined Networks (SDN), which promises to deliver network agility (create, update, delete, and restore networks on demand), increase the capability to rapidly introduce new services, and enhance security and user experience, among others. To support the network virtualization in SDDC, SDN controllers typically work with infrastructure network switches (physical or virtual) to enforce the policies as required based on customer workloads, and take care of the movement of policies whenever workloads move automatically. This removes the networking bottleneck as described above in traditional data centers. Additionally, dynamic changes required in the network from customer workloads/applications are automatically managed by the SDN controller, with SDN applications written on top of the SDN controller providing better network visibility and analytics, and more optimal allocation of network resources. This also allows SDDC to incorporate legacy physical appliances like databases, bare metal servers, network services such as physical firewalls, and load balancers, in addition to the virtual workloads (customer applications, virtual firewalls, and virtual load balancers) residing on multiple hypervisors in servers.
In summary, with the advent of SDN architecture, networks have become more agile in supporting network virtualization, and gave rise to SDDCs that have fully embraced virtualization technologies across server, storage, and network infrastructures and services to support ever-growing customer workloads and next-generation applications.
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