Agility

This is one of the new tenets of network design that was not talked about a couple of years ago. Networks were designed to be modular and flexible, but agile was a far-fetched thought primarily because the networks were meant to be static, or at least quasi-static. Changes were made to the network but that went through a complete change cycle, a design cycle, and hence was time consuming.

Today's business environment is dynamic, hence the networks need to be able to support these dynamic environments. Networks need to change at the speed of business if they are to be positive contributors to business. Hence, designing networks that are agile is a basic consideration in today's network design rather than an afterthought.

Agility means giving the network the ability to change quickly. The changes may include making routing changes based on the underlying network performance, bringing up new locations and integrating them with the network, making widespread changes on the network to meet new security threats, and so on. The list of use cases is endless.

Agility provides the network the capability of changing the way it handles traffic flows in response to any change in business requirements or network performance. Conventional networks were built using conventional hardware, and provisioned and configured using command-line interfaces. This meant shipping hardware to the remote site of a new office needed to be connected, leading to delays in bringing up new sites. Configuration on a device-by-device basis using the command-line interface meant that all devices had to be configured sequentially by operators leading to delays and often operator errors leading to availability issues. Technologies such as SDN and NFV and features such as Plug and Play have been the real enablers of making the networks agile.

The APIC-EM controller as defined in the DNA section and the applications running on top are examples of how SDN and network programmability are making networks more agile.