The purpose of modern data center networking is to accommodate multiple data center tenants with a variety of workloads. In such a network, servers are the components that provide users (and the programs working on their behalf) with requested services.
The simplest such networking services may be responses to API function calls. Servers may also provide users/clients with applications, by way of Web protocols, language platforms, or virtual machines that provide users with full desktops.
Inside Data Center Networking
Today, few business workloads – and progressively fewer consumer and entertainment workloads – are executed on single computers, hence the need for data center networking. Networks provide servers, clients, applications, and middleware with a common map with which to stage the execution of workloads, and also with which to manage access to the data they produce.
The coordinated work between servers and clients in a network is the workflow that requires data center networking between resources. Data is exchanged between servers and clients, although for modern data centers, there is no central overseer of such exchanges.
A conventional data center network comprises: servers that manage workloads and respond to client requests; switches that connect devices together; routers that perform packet forwarding functions; controllers that manage the workflow between network devices; gateways that serve as the junctions between data center networks and the broader Internet; and clients that act as consumers of the information in data packets.
Resources on the the network share a common mapping system based on networking standards or technologies. For modern networks, this shared map is often based on Internet Protocol (IP), Ethernet, and other related networking technologies. Layer 3 IP addresses (IP routing) are designed to give intermediate forwarding agents in a network, called routers, clues as to the general direction along which to move packets to data. Using Transport Control Protocol (TCP/IP), routers pass packets of data to each other, literally in a best-guess effort.
Another common data center technology is Ethernet, which connects devices using media access control (MAC) addresses. To overcome limitations of these basic networking technologies, many additional networking protocols have been developed, including VXLAN and OpenFlow, some of which may be executed as an “overlay” that rides on top of the basic networking infrastructure.
These components form the infrastructure of the data center network. As the infrastructure evolves, no longer must any of these components’ functions be served by stand-alone, physical appliances. Virtualization enables the role of any or all of these components to be fulfilled by software.
Software-Defined Data Center Networking
In a software-defined network (SDN), the dynamics of data center workflows change, in order to accommodate varying workloads more effectively and efficiently. Specifically, the workflow is split into two categories: the contents of the documents or media being used by clients (the data plane) and the instructions for how the network should accommodate this data (the control plane). This way, an SDN controller may make sweeping adjustments to the way the data plane is mapped, even while a workflow is in progress, without jeopardizing the control plane and the connections that bind the network components together.
A data center today is less bound to physical and geographic constraints than ever before. Technically, a data center is the collection of components that share a common IP address map with one another, and which may be (though not necessarily) joined together by a common domain. To the extent that the bandwidth of the underlying infrastructure permits it, a single data center may span the globe.
In conventional usage, however, enterprises and public services continue to perceive their data centers as the collection of servers that operate on premises that they own or lease. Yet even this interpretation is being worn away by new realities, the most prominent of these being the availability of cloud-based infrastructure and platforms made available to businesses “as-a-service” – sold on a subscription, or pay-as-you-go, basis.
How the Cloud Remaps Data Centers
The cloud has evolved to mean the use of network virtualization to decouple physical processors from the services they provide. That may not sound much like the colloquial term “the cloud,” with which consumers refer to the indeterminate storage space that holds their synchronized documents. Yet the data centers that comprise the cloud, as consumers perceive it, were made possible through virtualization.
For example, distributed file systems that encompass multiple volumes spanning a variety of domains, are the products of virtualized components that decouple addressable files from physical file systems. In large data center networks, SDN controllers are responsible for the management of these components; in smaller, though still reasonably vast, enterprise networks, virtual network overlays run by workload orchestrators, enable the pooling together of file systems.
As the nature of data center networking becomes more and more disaggregated, the notion of “center” becomes almost entirely abstract. Rather than a place where assets are managed and operated, a data center network may now be something no more concrete than the collection of information technology resources accessible by way of one another – which a business owns or leases, or to which it subscribes.