Cisco Stretching the ACI Networking Fabric

The latest release of the APIC software includes a feature that enables the ACI Fabric to link switches at sites up to 18.6 miles apart.

data center

Cisco Systems has seen strong adoption over the past year of its Application Centric Infrastructure technology, the vendor's answer to the growing network virtualization movement.

In the last financial quarter, Cisco saw the number of customers for the Application Centric Infrastructure (ACI) and the foundational Nexus 9000 switches increase to more than 1,700, and revenues for the switches increase 350 percent. It was enough to convince an ebullient CEO John Chambers to declare that Cisco was winning the contest in a software-defined networking (SDN) market that was supposed to threaten the company's future.

Now Cisco is enabling customers to stretch the ACI Fabric between data centers that are almost 20 miles apart. In the latest software release (1.0(3f)) of the Application Policy Infrastructure Controller (APIC) for the Nexus 9000 switches, Cisco is offering a feature—the Stretched Fabric—that enables each leaf and spine switch that is used to create a fabric to be located up to 30 kilometers (more than 18.6 miles) apart.

ACI fabrics are normally used at a single site, with the entire mesh design connecting every leaf switch to every spine switch in the fabric for improved throughput and convergence, Ravi Balakrishnan, senior product marketing manager for data center solutions at Cisco, wrote in a post on the company blog. Typically, full mesh connectivity is expensive or impossible, given the lack of fiber connections or the cost to connect each switch between the sites.

The Stretched Fabric capabilities leverage transit leaf switches, which are used to connect the spine switches at each site, without the need for special requirements or configurations, according to Balakrishnan.

According to the Cisco Website, when using the ACI Stretched Fabric capabilities, customers should provision at least two APIC nodes at one of the sites—usually the one that is considered the main site or the one with the most switches—and a third APIC node at the other site. The APIC nodes will automatically synchronize and offer all the controller functions to each site, according to Cisco officials.

"The key benefits of stretched fabric include workload portability and VM [virtual machine] mobility," Balakrishnan wrote. "The stretched ACI fabric behaves the same way as a regular ACI fabric, supporting full VMM [Virtual Machine Manager] integration. For example, one VMware vCenter operates across the stretched ACI fabric sites. The ESXi hosts from both sites are managed by the same vCenter and Distributed Virtual Switch (DVS). They are stretched between the two sites."

SDN and network-functions virtualization (NFV) are designed to help businesses and service providers that are trying to manage the rapidly changing network demands brought by such trends as mobility, big data and the cloud. Organizations are looking for the ability to build networks that are more automated, scalable, programmable and affordable than traditional infrastructures.

SDN and NFV do this by putting the control plane and network tasks into software that can run on less-expensive commodity hardware, such as white boxes. Many industry observers have said this threatens the core networking businesses of such companies as Cisco and Juniper Networks, which sell expensive networking gear.

However, white boxes bring their own challenges in such areas as management and integration, convincing some OEMs—such as Dell, Juniper and, most recently, Hewlett-Packard—to create branded open switches that can run software from a range of third parties, a trend Gartner analysts have termed "brite boxes."

Cisco introduced ACI in 2013, announcing a strategy that aims to get the best performance out of applications by using a combination of software and hardware to create networking infrastructures that can be optimized in both physical and virtual environments and that can leverage partnerships with other vendors. Cisco CEO Chambers stressed the architectural aspect of ACI, which includes the integration of networking, servers, storage appliances and security capabilities that isn't offered in white-box systems.

"We are pulling away from our competitors and leading in both the SDN thought leadership and customer implementations," he said last week. "ACI and APIC will become the cornerstone of the next generation of networking architectures for many years."