Welcome!

Java IoT Authors: Liz McMillan, Yeshim Deniz, Elizabeth White, Pat Romanski, Frank Lupo

Related Topics: SDN Journal, Java IoT, Microservices Expo, Linux Containers, Containers Expo Blog, Cloud Security

SDN Journal: Article

Resiliency in Controller-Based Network Architectures

At the core of SDN solutions is the concept of a controller

Last week Ivan Pepelnjak wrote an article about the failure domains of controller based network architectures. At the core of SDN solutions is the concept of a controller, which in most cases lives outside the network devices themselves. A controller as a central entity controlling the network (hence its name) provides very significant values and capabilities to the network. We have talked about these in this blog many times.

Centralized Control

When introducing a centralized entity into any inherently distributed system, the architecture of such a system needs to carefully consider failure domains and scenarios. Networks have been distributed entities, with each device more or less independent and a huge suite of protocols defined to manage the distributed state between all of them. When you think about it, it’s actually quite impressive to think about the extend of distribution we have created in networks. We have created an extremely large distributed system with local decision making and control. I am not sure there are too many other examples of complex distributed systems that truly run without some form of central authority.

It is exactly that last point that we networking folks tend to forget or ignore. Many control systems in the world have central control and management. And the vast majority of them work pretty well. Any complex manufacturing facility has centralized control over robots, belts and all other machinery that it may use. There usually is some distributed state and health checks at interfaces between machines and operations, but the entire end to end process is controller by a centralized entity.

The reason for this is not much different from the reason we are starting to deploy controllers in networks. Having a true end to end view of all available resources will provide better overall performance of and control over the network. A centralized entity can make choices and decisions that are related or dependent of previous choices based on information that may well be outside the reach of a typical system in distributed operation.

Architectural Choices

But the introduction of such an entity needs to be carefully architected and designed. The exact role of a controller in the day to day (or microsecond to microsecond) operation of a network becomes a critical choice, it defines the dependency of the network on the controller and as a result, the impact of a controller failure. At Plexxi we made a very deliberate architectural choice for our controller:

  • it cannot ever be in the data path of network traffic. Not for new flows, not for existing flows. Not for link failures. Not for switch failures.

The network has to run when the controller is not available. It has to run for existing attached devices, newly attached devices, existing flows and new flows. Of course we want the controller to be available all the time because it gives us the best visibility, but we very deliberately architected it so that the network keeps working if it isn’t.

To that purpose we split our controller into two separate components. The most visible (and perhaps even traditional in this new world of controller architecture) is our central controller. It’s software, runs on a VM or bare metal server and is the central coordinator. It maintains the database with all relevant data. It communicates with the switches. And the operator communicates with it through a GUI, or our APIs or Data Services Engine.

Then there is a distributed portion of the controller. It run on every Plexxi Switch. It communicates with the central controller and takes higher level configuration, policy and topology instructions, then passes them to the Switch software that turns this into configuration for the hardware etc. Similarly, things like statistics and state info from the Switch software is passed to the distributed portion of the controller, then passed back to the central controller.

Network Independence

But most importantly, Plexxi switches are fully capable of making forwarding decisions by themselves. They learn MAC addresses. They resolve ARP. They have L2 forwarding tables. They have L3 forwarding tables. And these tables themselves are not managed by the central controller. They are managed by each switch. What the central controller provides is topology information on how to reach other switches in a Plexxi domain. Out of the many paths through the fabric, which ones should be used and for what percentage of traffic. And hundreds of backup paths through that fabric if a link of switch fails. And those failures are communicated between the switches themselves, without involving the controller (who gets informed, but is not in the action path).

Having this very clear line in the sand of what the switches are responsible for and what the controller is responsible for allows us to worry (just a little) less about the 100% resiliency of the controller. Don’t get me wrong, we want the controller there, but your network will operate as you expect if its not. In his article, Ivan calls it “controller enhanced network infrastructure”. That works.

[Today's Fun Fact: All polar bears are left-handed. Or left-clawed. I would assume that means they tend to be more creative than other bears too.]

The post Resiliency in Controller based Network Architectures appeared first on Plexxi.

More Stories By Marten Terpstra

Marten Terpstra is a Product Management Director at Plexxi Inc. Marten has extensive knowledge of the architecture, design, deployment and management of enterprise and carrier networks.

@ThingsExpo Stories
SYS-CON Events announced today that Avere Systems, a leading provider of enterprise storage for the hybrid cloud, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Avere delivers a more modern architectural approach to storage that doesn't require the overprovisioning of storage capacity to achieve performance, overspending on expensive storage media for inactive data or the overbui...
With major technology companies and startups seriously embracing Cloud strategies, now is the perfect time to attend 21st Cloud Expo October 31 - November 2, 2017, at the Santa Clara Convention Center, CA, and June 12-14, 2018, at the Javits Center in New York City, NY, and learn what is going on, contribute to the discussions, and ensure that your enterprise is on the right path to Digital Transformation.
Most technology leaders, contemporary and from the hardware era, are reshaping their businesses to do software. They hope to capture value from emerging technologies such as IoT, SDN, and AI. Ultimately, irrespective of the vertical, it is about deriving value from independent software applications participating in an ecosystem as one comprehensive solution. In his session at @ThingsExpo, Kausik Sridhar, founder and CTO of Pulzze Systems, will discuss how given the magnitude of today's applicati...
Smart cities have the potential to change our lives at so many levels for citizens: less pollution, reduced parking obstacles, better health, education and more energy savings. Real-time data streaming and the Internet of Things (IoT) possess the power to turn this vision into a reality. However, most organizations today are building their data infrastructure to focus solely on addressing immediate business needs vs. a platform capable of quickly adapting emerging technologies to address future ...
Digital transformation is changing the face of business. The IDC predicts that enterprises will commit to a massive new scale of digital transformation, to stake out leadership positions in the "digital transformation economy." Accordingly, attendees at the upcoming Cloud Expo | @ThingsExpo at the Santa Clara Convention Center in Santa Clara, CA, Oct 31-Nov 2, will find fresh new content in a new track called Enterprise Cloud & Digital Transformation.
SYS-CON Events announced today that NetApp has been named “Bronze Sponsor” of SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. NetApp is the data authority for hybrid cloud. NetApp provides a full range of hybrid cloud data services that simplify management of applications and data across cloud and on-premises environments to accelerate digital transformation. Together with their partners, NetApp emp...
Widespread fragmentation is stalling the growth of the IIoT and making it difficult for partners to work together. The number of software platforms, apps, hardware and connectivity standards is creating paralysis among businesses that are afraid of being locked into a solution. EdgeX Foundry is unifying the community around a common IoT edge framework and an ecosystem of interoperable components.
As popularity of the smart home is growing and continues to go mainstream, technological factors play a greater role. The IoT protocol houses the interoperability battery consumption, security, and configuration of a smart home device, and it can be difficult for companies to choose the right kind for their product. For both DIY and professionally installed smart homes, developers need to consider each of these elements for their product to be successful in the market and current smart homes.
Join IBM November 1 at 21st Cloud Expo at the Santa Clara Convention Center in Santa Clara, CA, and learn how IBM Watson can bring cognitive services and AI to intelligent, unmanned systems. Cognitive analysis impacts today’s systems with unparalleled ability that were previously available only to manned, back-end operations. Thanks to cloud processing, IBM Watson can bring cognitive services and AI to intelligent, unmanned systems. Imagine a robot vacuum that becomes your personal assistant th...
SYS-CON Events announced today that Avere Systems, a leading provider of hybrid cloud enablement solutions, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Avere Systems was created by file systems experts determined to reinvent storage by changing the way enterprises thought about and bought storage resources. With decades of experience behind the company’s founders, Avere got its ...
SYS-CON Events announced today that Golden Gate University will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Since 1901, non-profit Golden Gate University (GGU) has been helping adults achieve their professional goals by providing high quality, practice-based undergraduate and graduate educational programs in law, taxation, business and related professions. Many of its courses are taug...
SYS-CON Events announced today that SIGMA Corporation will exhibit at the Japan External Trade Organization (JETRO) Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. uLaser flow inspection device from the Japanese top share to Global Standard! Then, make the best use of data to flip to next page. For more information, visit http://www.sigma-k.co.jp/en/.
High-velocity engineering teams are applying not only continuous delivery processes, but also lessons in experimentation from established leaders like Amazon, Netflix, and Facebook. These companies have made experimentation a foundation for their release processes, allowing them to try out major feature releases and redesigns within smaller groups before making them broadly available. In his session at 21st Cloud Expo, Brian Lucas, Senior Staff Engineer at Optimizely, will discuss how by using...
In this strange new world where more and more power is drawn from business technology, companies are effectively straddling two paths on the road to innovation and transformation into digital enterprises. The first path is the heritage trail – with “legacy” technology forming the background. Here, extant technologies are transformed by core IT teams to provide more API-driven approaches. Legacy systems can restrict companies that are transitioning into digital enterprises. To truly become a lead...
SYS-CON Events announced today that CAST Software will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. CAST was founded more than 25 years ago to make the invisible visible. Built around the idea that even the best analytics on the market still leave blind spots for technical teams looking to deliver better software and prevent outages, CAST provides the software intelligence that matter ...
SYS-CON Events announced today that Daiya Industry will exhibit at the Japanese Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Ruby Development Inc. builds new services in short period of time and provides a continuous support of those services based on Ruby on Rails. For more information, please visit https://github.com/RubyDevInc.
As businesses evolve, they need technology that is simple to help them succeed today and flexible enough to help them build for tomorrow. Chrome is fit for the workplace of the future — providing a secure, consistent user experience across a range of devices that can be used anywhere. In her session at 21st Cloud Expo, Vidya Nagarajan, a Senior Product Manager at Google, will take a look at various options as to how ChromeOS can be leveraged to interact with people on the devices, and formats th...
SYS-CON Events announced today that Yuasa System will exhibit at the Japan External Trade Organization (JETRO) Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Yuasa System is introducing a multi-purpose endurance testing system for flexible displays, OLED devices, flexible substrates, flat cables, and films in smartphones, wearables, automobiles, and healthcare.
SYS-CON Events announced today that Taica will exhibit at the Japan External Trade Organization (JETRO) Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Taica manufacturers Alpha-GEL brand silicone components and materials, which maintain outstanding performance over a wide temperature range -40C to +200C. For more information, visit http://www.taica.co.jp/english/.
SYS-CON Events announced today that SourceForge has been named “Media Sponsor” of SYS-CON's 21st International Cloud Expo, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. SourceForge is the largest, most trusted destination for Open Source Software development, collaboration, discovery and download on the web serving over 32 million viewers, 150 million downloads and over 460,000 active development projects each and every month.