Posted by: Shamus McGillicuddy
Avaya, Brocade, Cisco, data center networks, Networking, openflow, shortest path bridging, software-defined networking, TRILL
Many of the bloggers who have analyzed and reported on the news of Insieme, Cisco’s latest spin-in, have talked about how the company’s formation is a morale-killer for Cisco employees. The concern is justified. Cisco’s spin-in approach enriches a select number of employees recruited to join the likes of Insieme and other past spin-ins like Nuova Systems, leaving engineers who work on products like the Catalyst line or the Aironet products to wonder when their big payday will come. That can lead to a brain drain as engineers bolt for a company that gives them a better opportunity to shine.
But what about the technology strategy that is coalescing around Insieme and the other moves Cisco is making with software-defined networks? Shouldn’t the bigger concern be that Cisco might be making a strategic blunder?
Last week Cisco circulated an internal memo that confirmed for employees its $100-milllion investment in Insieme, the spin-in that will form part of Cisco’s “build, buy, partner” strategy for software-defined networking (SDN). The Cisco memo, published by Om Malik, claims that the networking industry hasn’t yet settled on a definition for SDN, let alone a value proposition:
Because SDN is still in its embryonic stage, a consensus has yet to be reached on its exact definition. Some equate SDN with OpenFlow or decoupling of control and data planes. Cisco’s view transcends this definition.
As Brad Casemore points out, here is Cisco’s opening salvo. It’s going to resist, or at least play down the value of, one of the core attributes of software-defined networking: the decoupling of the control and data planes. There is a little bit of cognitive dissonance with this statement. This decoupling of the control and data planes is an essential foundation of SDN. It enables centralized, flow-based networking. It enables programmability. It enables organizations to deploy third-party applications on a network through an SDN controller. But Cisco claims to transcend this idea. This vague dismissal should be troubling to SDN proponents.
The memo goes on to quote Cisco CTO Padmasree Warrior to support this notion:
“If you ask five customers what SDN means to them, you may get five different answers. Customer motivations and expectations are different based on their business problem or deployment scenario,” Warrior says.
It’s true that some people new to the subject initially perceived OpenFlow as an architecture, rather than just a protocol that enables SDN. Once they get educated on the subject, few networking pros express much confusion on the matter. However, is Cisco’s view really transcending the current SDN definition. This memo muddies the waters a bit by claiming that Cisco’s Nexus 1000v virtual switch is an example of SDN?
While SDN concepts like network virtualization may sound new, Cisco has played a leadership role in this market for many years leveraging its build, buy, partner strategy. For example, Cisco’s Nexus 1000V series switches—which provide sophisticated NX-OS networking capabilities in virtualized environment down to the virtual machine level—are built upon a controller/agent architecture, a fundamental building block of SDN solutions. With more than 5,000 customers today, Cisco has been shipping this technology for a long time.
Sure, the Nexus 1000v introduces a version of SDN to the extreme edge of a virtualized data center, but it doesn’t come close to achieving the network agility and programmability promised by software-defined networks enabled, or not enabled, by OpenFlow. What about the rest of the data center LAN, filled with physical switches that are so constrained that both the IETF and the IEEE are re-engineering Ethernet in order to eliminate a legacy protocol like spanning tree?
Proponents say that SDN has the potential to eliminate spanning tree by defining flow routes centrally in a server-based controller, thus eliminating the risk of loops. Why upgrade to Shortest Path Bridging (SPB) or Transparent Interconnections of Lots of Links (TRILL), when an SDN network that can do it? If you want to use TRILL or SPB in your data center network today, you need to upgrade to the newest generation of your vendor’s switches, and you won’t be able to reverse course midway through. These vendors won’t play together. You can’t mix Brocade’s iteration of TRILL with Cisco’s. You can’t mix Avaya’s iteration of SPB with Cisco or Brocade. You probably wouldn’t want to mix vendors in your data center, but you also want investment protection with these new data center fabrics, don’t you? Five years from now when you need to refresh the server access layer, you’re locked into whatever vendor you’ve chosen.
You can ditch spanning tree in an OpenFlow-based SDN network using any combination of switches that support OpenFlow. Heck, Nicira Networks claims its product can get you there without even using OpenFlow switches. Just leave your legacy network in place. You know who is using OpenFlow? Google. You know who is using Nicira? eBay. Fidelity. Rackspace. NTT. Concerns about scalability with SDN may be justified, but some heavyweight companies have put it into production.
But never mind that for now. The Cisco memo expounds on the virtues of open, programmable networks (something that Arista Networks has offered for a couple years now). Toward the end, the memo lifts the veil off of Cisco’s SDN approach.
“Our strategy is to continue to offer choices to our customers so that they are not forced to go down a single path,” Warrior says. “We have a multipronged approach that goes beyond current perceptions of SDN, leveraging business-based use cases as building blocks so that we achieve architectural consistency and bring to bear the richness of all our capabilities.”
Warrior adds that Cisco already builds a lot of intelligence into its network silicon and software. Making them open and programmable will further unlock the value, while enabling further application awareness.
I will give Cisco credit here. the industry needs more “business-based use cases” for SDN. Midsized enterprises and even many large enterprises do not need SDN today. The networking pros at these smaller companies who ask me about SDN are interested in the technology, but mostly they just want to stay current with technology. They don’t need it. Today the emerging SDN market is focused on serving the needs of larger enterprises and web-scale companies. Broader business cases for the technology are years away. Many SDN start-ups are focusing on cloud providers and web giants rather than enterprises.
However, the mention of network silicon above (translation: ASICs) worries me. Here we have Cisco saying that it will make its ASICs and its software (IOS, NX-OS) open and programmable. Just how open and programmable will Cisco’s technology be? Look at this job posting for a software engineer at Cisco (It may not last long. It’s been scrubbed of certain details since I first reported its existence a couple weeks ago. This and another job posting (which disappeared from Cisco’s website a few days ago) made many references to a ConnectedApps team that is developing APIs for a software development kit (SDK) that will open up Cisco’s technology to third-party developers as part of a SDN initiative.
Just how open and programmable will an initiative based on APIs be? This doesn’t sound like an API for OpenFlow. It sounds like something else, given Cisco’s downplay of OpenFlow. APIs are a way to allow third party developers to hook their software to another vendor’s proprietary software. There’s nothing particularly open about it. SDN is about more than hooking third-party software to the edge of Cisco’s black box, whether that black box is in the form of software or an ASIC. SDN is what it is: Networks defined by software rather than hardware. How do you do that? By opening up the black box of networks and letting engineers build their networks in new ways. There is a control plane and there is a data plane. SDN decouples them and opens up the network to a whole new world of possibilities. It’s as simple as that.
In a few years, more IT organizations will want an open, software-defined network. Cisco needs to find a way to be relevant in such a world. APIs won’t cut it.