ACI provides the ability to create a stateless definition of application requirements. Application architects think in terms of application components and interactions between such components; not necessarily thinking about networks, firewalls and other services. By abstracting away the infrastructure, application architects can build stateless policies and define not only the application, but also Layer 4 through 7 services and interactions within applications. Abstraction also means that the policy defining application requirements is no longer tied to traditional network constructs, and thus removes dependencies on the infrastructure and increases the portability of applications.
The application policy model defines application requirements, and based on the specified requirements, each device will instantiate a set of required changes. IP addresses become fully portable within the fabric, while security and forwarding are decoupled from any physical or virtual network attributes. Devices autonomously and consistently update the state of the network based on the configured policy requirements set within the application profile definitions.
What is Cisco Application Centric Infrastructure ACI?
It is SDN solution from Cisco for Data Centers, simply ACI is a Network policy based automation model
The end goal of this solution is about enabling software control of the network and how it operates, so that software can automate and change the network based on current conditions in the network.
ACI uses a concept of endpoints and policies. The endpoints are the VMs (or even traditional servers with the OS running directly on the hardware). Because several endpoints have the same needs, you group them together into aptly named endpoint groups. Then policies can be defined about which endpoint groups can communicate with whom—for instance, a group of web servers may need to communicate with a group of application servers. The policy also defines other key parameters, like which endpoint groups can access each other (or not), as well as QoS parameters and other services.
ACI uses a centralized controller called the Application Policy Infrastructure Controller (APIC),It is the controller that creates application policies for the data center infrastructure…..this is your SDN controller for Data Center.
ACI uses a partially centralized control plane, RESTful and native APIs, and OpFlex as an SBI. The NBIs allow software control from outside the controller. The controller communicates with the switches connected to the endpoints, and asks those switches to then create the correct flows to be added to the switches. Interestingly.
ACI has three main components: Nexus 9000 switches, APIC and ecosystem