What is Cisco ACI? This is part one of SDxCentral’s series to explain the Cisco ACI (Application Centric Infrastructure) framework and how it’s the Cisco SDN Solution. Check out Part 2 that details the Cisco Application Policy Infrastructure Controller or Cisco APIC. Cisco ACI is the solution that emerged from Cisco, following its acquisition of Insieme, which is a company they funded for more than two years. ACI is seen by many as Cisco’s software-defined networking (SDN) offering for data center and cloud networks.
How Cisco ACI Works
Cisco ACI is a tightly coupled policy-driven solution that integrates software and hardware. The hardware for Cisco ACI is based on the Cisco Nexus 9000 family of switches. The software and integration points for ACI include a few components, including Additional Data Center Pod, Data Center Policy Engine, and Non-Directly Attached Virtual and Physical Leaf Switches. While there isn’t an explicit reliance on any specific virtual switch, at this point, policies can only be pushed down to the virtual switches if Cisco’s Application Virtual Switch (AVS) is used, though there has been talk about extending this to Open vSwitch in the near future.
To a large extent, the network for Cisco ACI is no different than what has been deployed over the past several years in enterprise data centers. What is different, however, is the management and policy framework, along with the protocols used in the underlying fabric.
In a leaf-spine ACI fabric, Cisco is provisioning a native Layer 3 IP fabric that supports equal-cost multi-path (ECMP) routing between any two endpoints in the network, but uses overlay protocols, such as virtual extensible local area network (VXLAN) under the covers to allow any workload to exist anywhere in the network. Supporting overlay protocols is what will give the fabric the ability to have machines, either physical or virtual, in the same logical network (Layer 2 domain), even while running Layer 3 routing down to the top of each rack. Cisco ACI supports VLAN, VXLAN, and network virtualization using generic routing encapsulation (NV-GRE), which can be combined and bridged together to create a logical network/domain as needed.
From a management perspective, the central SDN Controller of the ACI solution, the Application Policy Infrastructure Controller (APIC) manages and configures the policy on each of the switches in the ACI fabric. Hardware becomes stateless with Cisco ACI, much like it is with Cisco’s UCS Computing Platform. This means no configuration is tied to the device. The APIC acts as a central repository for all policies and has the ability to rapidly deploy and re-deploy hardware, as needed, by using this stateless computing model.
Cisco ACI also serves as a platform for other services that are required within the data center or cloud environment. Through the use of the APIC, third party services can be integrated for advanced security, load balancing, and monitoring. Vendors and products, such as SourceFire, Embrane, F5, Cisco ASA, and Citrix can integrate natively into the ACI fabric and be part of the policy defined by the admin. Through the use of northbound APIs on the APIC, ACI can also integrate with different types of cloud environments.
How Cisco ACI Integrates with Other Products