Monday, November 18, 2013

Cisco ACI - SDN in the DC, Cisco's Way

As you may have read by now, Cisco has announced their first big 'SDN' (Software Defined Networking) solution named ACI (Application Centric Infrastructure) that tightly pairs with the Nexus 9000 line (announced along with ACI). However, with most product announcements that are released far in advance to the actual product release, the technical details are very few and far in-between. I recently had the opportunity to attend a conference where I attended an ACI and Nexus 9000 breakout session discussion with presenter Joe Onisick (, a Cisco TME for ACI/N9k.

From the discussions that followed, these were the interesting points and thoughts that stuck out to me about ACI and the N9k:

  • As Cisco has already stated, the N9k will be shipping soon, but they won't be able to run in ACI-mode until 2HCY14. The upgrade from standalone-mode (standard NX-OS) to ACI-mode will be a major upgrade, as the whole underlying OS/firmware is completely different. No ISSU upgrade.
  • The N9k and ACI is currently a Data Center only solution, in a CLOS fabric design (Spines and Leafs) with the APIC controller (Application Policy Infrastructure Controller). It was not designed to replace Core, WAN-edge, or Campus network environments - it will likely expand to these other environments after the technology gains momentum in the DC space. The whole concept of SDN is still very early in it's infancy - at least for everyone who isn't Google.
  • The N9k will be priced very competitively - partly due to the use of merchant silicon and mid-plane elimination - but I would say more importantly due to the DC-focused scope of software functionality. Technologies like OTV, LISP, etc will still require a N7k or ASR. Design guides will become available with how to integrate the ACI DC infrastructure with other areas of the network. Since it's using VXLAN as an overlay - there will certainly be a VXLAN-gateway functionality to have that integration.
  • 40G BiDi optics - man these are great (also announced along w/ ACI and the N9k)! 40GE over a single pair of OM3 MMF (good for 100m) using essentially CWDM, but only 2 waves (20G each). And they are able to manufacture and sell them very cost effectively. This could be a major Cisco differentiator when 40G becomes more of the norm. Businesses already have a lot of sunk cost into their fiber cable plants - would they rather replace/addon to accommodate the 12-strand MTP fiber cables for MMF 40G or use their existing 10G fiber plant? A 'no-brainer' decision. Some great info on them here:
  • How will the APIC controller look/feel/operate? It's still somewhat of a mystery, but I expect it to be very similar to the successful UCS Manager (configuring network/application policies with various metrics/SLAs). After all, the people at Insieme were also the people who created UCS and the Nexus products.
  • NSH - Network Service Header - a Cisco vPath-like technology that has been submitted to the IETF as a draft ( See who co-authored it? Cisco and a certain company Cisco announced they were acquiring at the launch of ACI (Insieme). This appears to be one of the major underlying technologies that the APIC (the controller) will use to chain network services (firewalls, load balancers, etc). vPath is a really cool technology that the Cisco Nexus 1000v uses to communicate with VMware ESX and virtual network appliances (VSG, vASA, etc) for logically 'chaining' network services. That makes the Cisco AVS (Application Virtual Switch, also announced along w/ ACI) seem to fit quite nicely in the mix, as it's essentially a Nexus 1000v that communicates with the ACI infrastructure. With NSH having a fixed header, it makes it easily implemented into hardware - essentially doing the same function of the N1000v and vPath, but with the ability to have hardware ASICs participate in the service chaining.
Starting to see the potential of ACI now? There are still lots of technical details that are missing, and for that matter the actual product. It'll be very interesting to see how the market reacts to ACI and VMware's NSX. VMware has already released NSX, but will customers adopt it? Will NSX be production-ready by the time ACI/APIC are released; will customers see the need for tighter integration with network and other hardware (VMware has stated that they are working with networking vendors for interop, but how well will that turn out)? All questions that come to mind in terms of the race to see who wins SDN in the DC. The next couple years in the networking field are going to be really interesting.

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