• 11/05/2013
    6:51 PM
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Cisco ACI Solves All Your Data Center Network Problems

Cisco launches its Application Centric Infrastructure (ACI), bringing open overlay networking and SDN to the entire data center.
Nexus 9000 and Beyond

Cisco is announcing another switching platform that is able to work with the APIC controller and provide ACI functions. The Nexus 9000 product family uses Broadcom Trident 2 merchant silicon to provide 10 Gigabit and 40 Gigabit Ethernet switching. As a technology, the hardware has little to differentiate it from competitors besides its size and the fact that it doesn't use Cisco's own switch silicon. Compared to other Cisco products, it consumes less power, space and is much lower cost.

The Nexus 9000 switches use an overhauled version of the NX-OS software that combines with Broadcom Trident silicon to provide the connectivity and orchestration between the virtual network and the physical network. NX-OS Plus delivers the necessary API support for the APIC to query and update the device. It also enables greater control of the flows and functions in the device through the use of customized software drivers for Trident 2 silicon.

My view is that customers should focus on the fixed format switches that are also rolling out and deploy scalable Layer 3 ECMP designs at much less cost. The Nexus 9000 chassis is oversized for all but largest data centers. These new Nexus 9300 top-of-rack switches will easily replace most of the older and tired Catalyst 4500 and 6500 switches in the data center. At a physical level, the port density and forwarding performance is similar to other Trident 2 products on the market. Check out the data sheets for details.

More on NX-OS Plus and Network Protocols

Cisco is also releasing yet another software train where "NX-OS Plus forms the basis of the operating system in the Nexus 9000" and provides the software interfaces for network function. This NX-OS Plus firmware seems to be an overhauled version of NX-OS created by Insieme during its startup phase. NX-OS Plus provides the API support for APIC and deeper integration with the silicon to provide the necessary control functions over ternary content addressable memory (TCAM) and binary content addressable memory (BCAM) for flow management.

NX-OS Plus will be available for some models of existing Nexus 7000 equipment, allowing their inclusion in the APIC infrastructure stack. There were also hints that most Cisco business units are planning to enable APIC capability, although this will likely take some years to arrive.

It's my understanding that the APIC relies on proprietary extensions in network frame format. These are based on the IEEE 802.1BR standard called VNtag/VNLink and usually known as fabric extension or FEX. FEX is already widely used in the Cisco UCS and the Nexus 7K/5K/2K products, but I was unable to confirm the details of its use in the new launches at this time.

Cisco has either extended the VXLAN packet format with VNtag/VNLink data or used VNtag/VNLink so that its internal solution is independent of the overlay protocol. While we don't yet have deep technical detail on how the ACI technology works at the network level, I will hazard a guess that it is close to Dynamic Fabric Automation, using a specialized tag format to provide in-band tenancy data in combination with control plane state.

Today's product announcement is all about ACI strategy, the APIC controller and Nexus 9000 hardware, but integration with hypervisors remains a key topic. Both OpenStack and vCloud Director are vital product strategies that Cisco must capture in the months ahead. The Nexus 1000 software switching has some early support for APIC, but that's yet to come.

But Wait, There's More!

Cisco is also attempting to address the larger business problems relating to networking and change management. These are focused around service insertion. Cisco is emphasizing its longstanding relationships with other vendors that are pledging to support APIC in the early stages. For customers who are managing complex network services with a range of appliances, it is reassuring to know their existing investments will be maintained.

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