Hot on the heels of Hewlett-Packard announcing its OpenSwitch open source switch operating system, Big Switch Networks, a provider of software-defined networking tools based on the OpenFlow protocol, and Facebook, one of the world’s largest hyperscalers and an adamant proponent of open networking, have crafted their own open source network operating system.
The two are demonstrating the pairing of OpenNetLinux from Big Switch and FBOSS from Facebook, which together comprise a basic switch operating system that can – and probably will – compete with HP’s OpenSwitch as well as alternatives from Cumulus Networks, Pluribus Networks, Pica8, and others. This competition across various NOS stacks, both on the technical merits and the relative openness of their software, is healthy for the nascent open networking space.
“We started out two years ago to create the bottom half of a switch operating system, with all of the knobs open for other organizations to be able to implement the top half themselves,” Rob Sherwood, chief technology officer at Big Switch, tells The Next Platform. “Working with Facebook and the Open Compute Project community, the goal is to solve low-level hardware driver problems so engineers can write what they want on top. OpenNetLinux does ship with some example code to implement a switch operating system, but it was never to be the thing that companies would deploy all by itself, but it does enable a DIY switch OS. Our interest in this, honestly, is to accelerate the adoption of open hardware.”
You do not have to buy Big Switch’s OpenFlow networking stack to make OpenNetLinux useful, although that is one path that prospective customers can take. The point of OpenNetLinux is to lower the barrier to entry for those companies that – for whatever reason – want to write their own switch operating system, or cobble one together from various open source projects, like the Facebook FBOSS code that has also been contributed to Open Compute.
“If you look at the hyperscale community, where we spend a lot of time, there is this interesting dynamic that is happening,” Kyle Forster, a seasoned Cisco executive who was one of the co-founders of Big Switch, which was founded back in March 2010 and which uncloaked from stealth mode in November 2012 with its OpenFlow controller. “The hyperscale companies that are creating their own switch OSes are writing this bottom half independently, and we thought there was an opportunity to aggregate that. But they really disagree very strongly on the top half – what we call pluggable forwarding agents. Facebook has FBOSS, Google has its own, and Microsoft has its own strong opinions. By splitting this layer out, we found common ground where we can get the hyperscalers to agree.”
In a metaphorical sense, this layer is a bit like the kernel in the an operating system, and in fact it is based on the Linux kernel, albeit one stripped down and designed explicitly for switches instead of servers. Even the one at Microsoft, called the Azure Cloud Switch, is based on Linux as the company recently revealed.
The OpenNetLinux project is still pretty new, and its software is still being fleshed out, and Forster says that it is still a little bit early to expect for hyperscalers like Google, Amazon, and Facebook, who have created their own network software stacks, to move over to OpenNetLinux. “But certainly the reason we did OpenNetLinux is to move the industry in this direction,” he says, without commenting on their plans.
We can envision the typical customers we follow at The Next Platform – large enterprises (particularly telecom companies and service providers), HPC centers, cloud builders, as well as hyperscalers – all being interested in open networking and being able to put together a network stack that precisely fits and its tuned for their workloads. If hyperscale and HPC teaches us anything, it is the value of precisely matching the infrastructure to the workload for maximum efficiency. So open networking might be born out of hyperscale, but it will make its way into other parts of the market, just like Linux was initially adopted for web hosting and HPC and gradually made its way onto every surviving kind of system in just about every niche except small business servers where Windows Server still rules.
It remains to be seen, says Sherwood, how the HP OpenSwitch effort and OpenNetLinux can or will coexist or cooperate. The Big Switch team is going to comb through the OpenSwitch code to see what is in there, but on first glance, Sherwood thinks that HP has taken a basic Linux kernel as its bottom half of the NOS and put a “very interesting” top half on it, much as Google, Facebook, Microsoft, and Amazon have done with their homegrown software. The issue now becomes how has the larger hardware compatibility list for that bottom half, including not just network ASICs from multiple vendors, but also support for other elements of the switches such as cables, optics, light indicators, fans, sensors, and such.
“This is really at the home brew computer club phase right now,” says Forster, but so was Linux back in the mid-1990s and then it was driving the industry and the whole open source movement only a few years later. “The one thing we know for sure is that whether we are talking about OpenNetLinux or OpenSwitch, the traditional L2 and L3 switch OS is getting commoditized and so is traditional switching hardware.”
Pica8 has said publicly that it will be moving its NOS on top of OpenNetLinux, and the Japanese carrier NTT (which has its own OpenFlow controller called Ryu) is doing a demo of its own “Lagopus” software switch atop OpenNetLinux. And aside from Big Switch’s own OpenFlow pluggable forwarding agents, Sherwood says there are graduate students all over the world who are monkeying around with OpenNetLinux and adding things to it and on top of it.
This is exactly how OpenFlow, which breaks the data plane from the control plane in a switch and allows the latter to be reconfigured across a bunch of switches on the fly from a central controller, got its start. And Big Switch should know, because Guido Appenzeller, who ran the Clean Slate Lab at Stanford University that gave birth to the OpenFlow standards, was co-founder and CEO at Big Switch. Interestingly, Appenzeller is chief technology strategy officer at the Networking and Security business unit at VMware and has been a force for the virtualization juggernaut’s joining up with HP on the OpenSwitch effort.
When all is said and done, OpenSwitch could end up replacing the bottom half of its stack with OpenNetLinux and creating an even more powerful option in fighting against the closed switches sold by industry giant Cisco Systems. It seems likely that Arista Networks, which has joined the OpenSwitch effort, will investigate how to incorporate elements of OpenSwitch and OpenNetLinux in its own EOS, Linux-based network operating system. In fact, all of the switch makers and those who have created their own NOS stacks have to stop and see what this all might mean for their futures. Those that have more value higher up in the stack – such as VMware and Big Switch – are best positioned for the long haul in terms of making money. Just selling a switch with a Broadcom ASIC and a proprietary NOS is not going to be much of a business plan.
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