This is the second of a two-part blog series developed in association with Tom Edsall, a Cisco Fellow and CTO of Insieme Networks, recently acquired by Cisco Systems. While Part 1focused on the role of SDN overlays and deployment considerations, this one delves into the benefits derived from such a model in an ACI implementation.
First, an insight into these design principles and the focus on applications from some of the top Insieme engineers-
Benefits of Overlay Integration in ACI deployments
If you have a small amount of state to update when an application moves or is added to the data center you will scale better than if you have a lot of state to update. With the ACI implementation, we are pretty fortunate in that the amount of state required by the mapping database is relatively small. It is a simple binding of identity to location. There is other state not related to the overlay such as access policy which may be larger, but that will be discussed at another time as it is not strictly required for the overlay. The amount of state that changes for a single move does not change with the size of the data center.
This is a two-part blog series developed in association with Tom Edsall, a Cisco Fellow and CTO of Insieme Networks, recently acquired by Cisco Systems. The intent is to elaborate on foundational design principles of Application Centric Infrastructure (ACI), a transformational approach for next-generation and cloud deployments. While the vision of ACI is an expansive one, this blog series focuses on the role of SDN overlays, their deployment considerations, as well as benefits that customers could derive from the unique implementation of overlays in an ACI solution.
The philosophy of Application Centric Infrastructure
Cisco’s Application Centric Infrastructure approach focuses on the most important thing in the data-center: applications. Without applications, we would not even need a data center at all! Everything we do in the data center ultimately is used to support those applications and the data that they work on because that is what ultimately drives business value.
The modern data center must be able to deploy applications rapidly, using any and all resources (compute, storage, network) available in the data center at any time. It must also be possible to grow, shrink, and move applications as needed. This will drive business agility and efficient use of resources.
The problem is that classical networking systems were developed in a world where there was less focus on any application anywhere, any time. Instead the focus was on on building large, static, IP networks.
Our solution was to create an application centric infrastructure where the emphasis is on the application rather than on the network. In order to do this we had to change the abstraction of the network from one that is, well, network centric to one that is application centric. In addition, we had to employ some SDN techniques to change the network from a traditional static infrastructure to a more dynamic, agile, flexible infrastructure. Let’s look into some of these techniques in detail.
Integrating SDN concepts
We employ two important concepts used in typical SDN solutions: overlays and a centralized controller. Overlays give us network flexibility that was never possible before by separating the location of a device from its identity. The centralized controller gives us consistent network behavior wherever an application is deployed, the application centric abstraction of the network, and a single point of control. While these benefits are important, even fundamental, to building a data center capable of supporting the business requirements of application agility, they also introduce their own set of problems in traditional SDN deployments that must be addressed. We will discuss these issues and their solutions shortly.
The SDN overlay and application abstraction is built on top of networking hardware that must move data across the data center quickly and efficiently without requiring changes to the applications, servers or storage elements attached to it. The hardware must do this in an efficient, reliable manner and provide as much assistance as possible to the network operator when troubleshooting and monitoring those applications as they use the network. Lastly, this hardware must be cost effective, power efficient, and space efficient.