Welcome!

SDN Journal Authors: Elizabeth White, David Paquette, Olivier Huynh Van, Pat Romanski, Dana Gardner

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

SDN Journal: Blog Feed Post

Why Network Load Balancing Is Not the Same as Application Load Balancing

Things you need to know before diving into SDN...

Way back in the early days of the Internet scalability was an issue (the more things change...). One of the answers to this problem was to scale out web servers using a fairly well-proven concept called load balancing. Simply put, distribute the load across web servers to make sure everyone gets served in a timely fashion. We see this in action at stores every day when more checkout lines are added as demand increases. Well, we hope we see this in action. Too often we don't, much to our chagrin.

Anyway, the way in which early load balancing worked was simply to take a couple variables (IP address and TCP port) and then hash them together and stick them in the equivalent of a queue for a web server. Because hash values tend to distribute fairly evenly, this worked well (until we ran into the mega-proxy issue, thanks to folks like Compuserve and AOL).

This is called "network load balancing" because, well, it uses network variables to distribute load. It's quite fast, actually, because it's based on variables that are in fixed locations within a single packet: source or destination IP and TCP port. All the work is on the ingress, on the inbound side, and once the decision has been made it's a pretty simple thing to hash future packets and match it up before sending it on its way. Voila. Network load balancing.

Application load balancing, however, arose because network load balancing was all based on inbound variables. It couldn't take into consideration how loaded the chosen server was, or whether its response time was falling within acceptable business parameters, or whether it was at capacity or not. Those variables were all on the server side, and required visibility into the application, not the client.

It also couldn't account for the fact that virtual servers were popping up everywhere (multiple applications served from the same IP address and port) and forced the web server to become a load balancer itself. Which, if you think about it, was kind of crazy. If a single server couldn't scale well enough to meet demand, how is putting a single server in front of them going to help the situation?

Application load balancing (which has also been given other fancy names over the years like content switching or routing, application switching, application or page routing, etc...) is really focused on distributing load across applications intelligently. While it can use ingress variables like IP address and port, it generally doesn't because that doesn't offer the insight into which server (application, web, virtual, whatever) is going to be able to respond (has capacity) in a time frame acceptable to the business (response time) for a specific application (or piece of the application like images).

The difference between the two lies primarily in the variables used to distribute load. Network load balancing relies solely on network variables while Application load balancing relies mainly on application variables.

This change in load balancing techniques opened up all sorts of new efficiencies and scalability options because it allowed architectures to specialize - route requests for images to servers focused on serving images, requests for static content to servers focused on serving static content, etc...). It also enabled persistence (sticky sessions) which greatly accelerated the ability to scale out stateful applications in a web format.

Why Is It Important to SDN?
The reason this is important to SDN architectures is because layer 3 switches can, in fact, support network load balancing. Fairly easily, in fact. If you look at how Link Aggregation (trunking) is implemented in most switches, you'll see it's using network load balancing techniques to distribute load across trunked links and that the algorithms used are pretty much the same ones we used back in the day to load balancing servers based on network variables. The hash is pretty simple (and easily implemented) and doesn't require storing state because the hash is always based on the same variables, easily extracted from IP and TCP headers, and don't really tax the system. Forwarding tables are basically sets of inbound IP addresses, TCP ports and (switch) ports matched to outbound IP addresses, TCP ports and (switch) ports. So you can see that network load balancing wouldn't overly tax a controller (it just has to hash the right values and insert a forwarding entry) or a switch.

But it wouldn't be application centric, or be able to take into consideration things that modern load balancing services care about - like application status, connection capacity, and response times, not to mention enabling specialization of services. But in order to be application centric application load balancing must participate in the data path and have visibility into variables that aren't available in packets - they're in payloads and in the application server (instances) itself. Like the implications of being stateful versus stateless, the burden on a centralized controller would be overwhelming.

Thus while SDN principles are certainly applicable, the same architecture used to implement SDN for lower order network layer services is not going to be the same architecture used to implement SDN for higher order network layer services. When evaluating SDN solutions, it's again important to consider how any two SDN network (core and application) architectures complement one another, integrate with one another, and collaborate to enable a complete software-defined network architecture that supports the unique needs of both layer 2-3 and layer 4-7.

Read the original blog entry...

More Stories By Lori MacVittie

Lori MacVittie is responsible for education and evangelism of application services available across F5’s entire product suite. Her role includes authorship of technical materials and participation in a number of community-based forums and industry standards organizations, among other efforts. MacVittie has extensive programming experience as an application architect, as well as network and systems development and administration expertise. Prior to joining F5, MacVittie was an award-winning Senior Technology Editor at Network Computing Magazine, where she conducted product research and evaluation focused on integration with application and network architectures, and authored articles on a variety of topics aimed at IT professionals. Her most recent area of focus included SOA-related products and architectures. She holds a B.S. in Information and Computing Science from the University of Wisconsin at Green Bay, and an M.S. in Computer Science from Nova Southeastern University.

@CloudExpo Stories
Ask someone to architect an Internet of Things (IoT) solution and you are guaranteed to see a reference to the cloud. This would lead you to believe that IoT requires the cloud to exist. However, there are many IoT use cases where the cloud is not feasible or desirable. In his session at @ThingsExpo, Dave McCarthy, Director of Products at Bsquare Corporation, will discuss the strategies that exist to extend intelligence directly to IoT devices and sensors, freeing them from the constraints of ...
Let’s face it, embracing new storage technologies, capabilities and upgrading to new hardware often adds complexity and increases costs. In his session at 18th Cloud Expo, Seth Oxenhorn, Vice President of Business Development & Alliances at FalconStor, discussed how a truly heterogeneous software-defined storage approach can add value to legacy platforms and heterogeneous environments. The result reduces complexity, significantly lowers cost, and provides IT organizations with improved efficienc...
Businesses are struggling to manage the information flow and interactions between all of these new devices and things jumping on their network, and the apps and IT systems they control. The data businesses gather is only helpful if they can do something with it. In his session at @ThingsExpo, Chris Witeck, Principal Technology Strategist at Citrix, will discuss how different the impact of IoT will be for large businesses, expanding how IoT will allow large organizations to make their legacy ap...
19th Cloud Expo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy. Meanwhile, 94% of enterpri...
Complete Internet of Things (IoT) embedded device security is not just about the device but involves the entire product’s identity, data and control integrity, and services traversing the cloud. A device can no longer be looked at as an island; it is a part of a system. In fact, given the cross-domain interactions enabled by IoT it could be a part of many systems. Also, depending on where the device is deployed, for example, in the office building versus a factory floor or oil field, security ha...
SYS-CON Events announced today that CDS Global Cloud, an Infrastructure as a Service provider, will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. CDS Global Cloud is an IaaS (Infrastructure as a Service) provider specializing in solutions for e-commerce, internet gaming, online education and other internet applications. With a growing number of data centers and network points around the world, ...
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 lea...
24Notion is full-service global creative digital marketing, technology and lifestyle agency that combines strategic ideas with customized tactical execution. With a broad understand of the art of traditional marketing, new media, communications and social influence, 24Notion uniquely understands how to connect your brand strategy with the right consumer. 24Notion ranked #12 on Corporate Social Responsibility - Book of List.
Why do your mobile transformations need to happen today? Mobile is the strategy that enterprise transformation centers on to drive customer engagement. In his general session at @ThingsExpo, Roger Woods, Director, Mobile Product & Strategy – Adobe Marketing Cloud, covered key IoT and mobile trends that are forcing mobile transformation, key components of a solid mobile strategy and explored how brands are effectively driving mobile change throughout the enterprise.
Technology vendors and analysts are eager to paint a rosy picture of how wonderful IoT is and why your deployment will be great with the use of their products and services. While it is easy to showcase successful IoT solutions, identifying IoT systems that missed the mark or failed can often provide more in the way of key lessons learned. In his session at @ThingsExpo, Peter Vanderminden, Principal Industry Analyst for IoT & Digital Supply Chain to Flatiron Strategies, will focus on how IoT de...
SYS-CON Events announced today that LeaseWeb USA, a cloud Infrastructure-as-a-Service (IaaS) provider, will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. LeaseWeb is one of the world's largest hosting brands. The company helps customers define, develop and deploy IT infrastructure tailored to their exact business needs, by combining various kinds cloud solutions.
DevOps at Cloud Expo – being held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA – announces that its Call for Papers is open. Born out of proven success in agile development, cloud computing, and process automation, DevOps is a macro trend you cannot afford to miss. From showcase success stories from early adopters and web-scale businesses, DevOps is expanding to organizations of all sizes, including the world's largest enterprises – and delivering real results. Am...
There is little doubt that Big Data solutions will have an increasing role in the Enterprise IT mainstream over time. Big Data at Cloud Expo - to be held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA - has announced its Call for Papers is open. Cloud computing is being adopted in one form or another by 94% of enterprises today. Tens of billions of new devices are being connected to The Internet of Things. And Big Data is driving this bus. An exponential increase is...
Big Data has been changing the world. IoT fuels the further transformation recently. How are Big Data and IoT related? In his session at @BigDataExpo, Tony Shan, a renowned visionary and thought leader, will explore the interplay of Big Data and IoT. He will anatomize Big Data and IoT separately in terms of what, which, why, where, when, who, how and how much. He will then analyze the relationship between IoT and Big Data, specifically the drilldown of how the 4Vs of Big Data (Volume, Variety,...
Cloud computing is being adopted in one form or another by 94% of enterprises today. Tens of billions of new devices are being connected to The Internet of Things. And Big Data is driving this bus. An exponential increase is expected in the amount of information being processed, managed, analyzed, and acted upon by enterprise IT. This amazing is not part of some distant future - it is happening today. One report shows a 650% increase in enterprise data by 2020. Other estimates are even higher....
The Internet of Things can drive efficiency for airlines and airports. In their session at @ThingsExpo, Shyam Varan Nath, Principal Architect with GE, and Sudip Majumder, senior director of development at Oracle, will discuss the technical details of the connected airline baggage and related social media solutions. These IoT applications will enhance travelers' journey experience and drive efficiency for the airlines and the airports. The session will include a working demo and a technical d...
Adobe is changing the world though digital experiences. Adobe helps customers develop and deliver high-impact experiences that differentiate brands, build loyalty, and drive revenue across every screen, including smartphones, computers, tablets and TVs. Adobe content solutions are used daily by millions of companies worldwide-from publishers and broadcasters, to enterprises, marketing agencies and household-name brands. Building on its established design leadership, Adobe enables customers not o...
Creating replica copies to tolerate a certain number of failures is easy, but very expensive at cloud-scale. Conventional RAID has lower overhead, but it is limited in the number of failures it can tolerate. And the management is like herding cats (overseeing capacity, rebuilds, migrations, and degraded performance). Download Slide Deck: ▸ Here In his general session at 18th Cloud Expo, Scott Cleland, Senior Director of Product Marketing for the HGST Cloud Infrastructure Business Unit, discusse...
SYS-CON Events announced today that Interface Masters Technologies, a leader in Network Visibility and Uptime Solutions, will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Interface Masters Technologies is a leading vendor in the network monitoring and high speed networking markets. Based in the heart of Silicon Valley, Interface Masters' expertise lies in Gigabit, 10 Gigabit and 40 Gigabit Eth...
SYS-CON Events announced today the Enterprise IoT Bootcamp, being held November 1-2, 2016, in conjunction with 19th Cloud Expo | @ThingsExpo at the Santa Clara Convention Center in Santa Clara, CA. Combined with real-world scenarios and use cases, the Enterprise IoT Bootcamp is not just based on presentations but with hands-on demos and detailed walkthroughs. We will introduce you to a variety of real world use cases prototyped using Arduino, Raspberry Pi, BeagleBone, Spark, and Intel Edison. Y...