|By Lori MacVittie||
|January 30, 2013 10:00 AM EST||
One of the premises of SDN and cloud scalability is that it's easy to simply replicate services - whether they be application or network focused - and distribute traffic across them to scale infinitely.
In theory, this is absolutely the case. In theory, one can continue to add capacity to any layer of the data center and simply distribute requests across the layer to scale out as necessary.
Where reality puts a big old roadblock in the way is when services are stateful. This is the case with many applications - much to the chagrin of cloud and REST purists, by the way - and it is also true with a significant number of network devices. Unfortunately, it is often these devices that proponents of network virtualization target without offering a clear path to addressing the challenges inherent in scaling stateful network devices.
SDN's claims to supporting load balancing, at least at layer 4, are almost certainly based on traditional, dumb layer 4 load balancing. We use the term "dumb" to simply mean that it doesn't care about the payload or the application or anything else other than its destination port and service and does not participate in the flow. In most layer 4 load balancing scenarios for which this is the case, the only time the load balancer examines the traffic is when processing a new connection. The load balancer may buffer enough packets to determine some basic networking details - source and destination IP and TCP ports - and then it establishes a connection between the client and the server. From this point on, generally speaking, the load balancer assumes the role of a simple forwarder. Subsequent packets with the same pattern are simply forwarded on to the destination.
If you think about it, this is so close to the behavior described by an SDN-enabled network as to be virtually the same. In an SDN-enabled network, a new flow (session if you will, in the load balancing vernacular) would be directed to the SDN controller for processing. The SDN controller would determine its destination and inform the appropriate network components of that decision. Subsequent packets with the same pattern would be forwarded on to the destination according to the information in the FIB (Forwarding Information Base). As the load balancing service was scaled out, inevitably packets would be distributed to components lacking an entry in the FIB. Said components would query the controller, which would simply return the appropriate entry to the device.
In such a way, simple layer 4 load balancing can be achieved via SDN*.
However, the behavior of the layer 4 load balancing service described is stateless. It does not actively manage the flow. Aside from the initial inspection and routing decision, the load balancing service is actually just a bump in the wire, forwarding packets much in the same manner as any other switch in the network.
But what happens when the load balancing service is actively participating in the flow, i.e. it is stateful.
Scaling Stateful Devices
Stateful devices are those that actively manage a flow. That is, they may inspect, manipulate, or otherwise interact with flows in real-time. These devices are often used for security - both ingress and egress - as well as acceleration and optimization of application exchanges. They are also use for content transformation purposes, such as XML or SOA gateways, API management, and other application-focused scenarios. The most common use of stateful devices is persistent load balancing, aka sticky sessions, aka server affinity. Persistent load balancing requires the load balancing service (or device) maintain a mapping of user to application instance (or server, in traditional, non-virtualized environments). This mapping is unique to the device, and without it a wide variety of applications break when scaled - VDI being the most recent example of an application relying on persistence of sessions .
In all these cases, however, one thing is true: the device providing the service is an active participant. The device maintains service-specific information regarding a variety of variables including the user, the device, the traffic, the application, the data. The entire context of the session is often maintained by one or more devices along the traffic chain.
What that means is that, like stateful, shared-nothing applications, it matters to which device a specific request is directed. While certainly the same model used at layer 4 and below in which a central controller (or really bank of controllers) maintains this information and doles it on on-demand, the result is that depending on the distribution algorithm used, every stateful device would end up with the same flows installed. In the interim, the network is frantically applying optimization and acceleration policies to traffic that may be offset by the latency introduced by the need to query the controller for session state information, resulting in a net loss of performance experienced by the end-user.
And we're not even considering the impact of secured traffic on such a model, where any device needing to make decisions on such traffic must have access to the certificates and keys used to encrypt the traffic in order to decrypt, examine, and usually re-encrypt the traffic. Stateful network devices - application delivery controllers, intrusion prevention and detection systems, secure gateways, etc... - are often required to manage secured content, which means distributing and managing certificates and keys across what may be an ever-expanding set of network devices.
The reality is that stateful network devices are a necessary and integral component of not just networks but applications today. While modern network architectures like SDN bring much needed improvements to provisioning and management of large scale networks, their scaling models are based on the premise of stateless, relatively simple devices not actively participating in flows. For those devices that rely upon deep participation in the flow, this model introduces a variety of challenges that may not find a solution that fits well with SDN without compromising on performance outside new protocols capable of carrying that state persistently throughout the lifetime of a session.
* This does not address the issue of resources required to maintain said forwarding tables in a given device, which given current capacity of commoditized switches supported for such a role seems unlikely to be realistically achieved.
Container technology is sending shock waves through the world of cloud computing. Heralded as the 'next big thing,' containers provide software owners a consistent way to package their software and dependencies while infrastructure operators benefit from a standard way to deploy and run them. Containers present new challenges for tracking usage due to their dynamic nature. They can also be deployed to bare metal, virtual machines and various cloud platforms. How do software owners track the usag...
Aug. 5, 2015 07:00 AM EDT Reads: 297
In their session at 17th Cloud Expo, Hal Schwartz, CEO of Secure Infrastructure & Services (SIAS), and Chuck Paolillo, CTO of Secure Infrastructure & Services (SIAS), provide a study of cloud adoption trends and the power and flexibility of IBM Power and Pureflex cloud solutions. In his role as CEO of Secure Infrastructure & Services (SIAS), Hal Schwartz provides leadership and direction for the company.
Aug. 4, 2015 06:45 PM EDT Reads: 243
There are many considerations when moving applications from on-premise to cloud. It is critical to understand the benefits and also challenges of this migration. A successful migration will result in lower Total Cost of Ownership, yet offer the same or higher level of robustness. In his session at 15th Cloud Expo, Michael Meiner, an Engineering Director at Oracle, Corporation, analyzed a range of cloud offerings (IaaS, PaaS, SaaS) and discussed the benefits/challenges of migrating to each offe...
Aug. 4, 2015 06:45 PM EDT Reads: 220
SYS-CON Events announced today that the "Second Containers & Microservices Expo" will take place November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Containers and microservices have become topics of intense interest throughout the cloud developer and enterprise IT communities.
Aug. 4, 2015 05:30 PM EDT Reads: 106
As organizations shift towards IT-as-a-service models, the need for managing and protecting data residing across physical, virtual, and now cloud environments grows with it. CommVault can ensure protection and E-Discovery of your data – whether in a private cloud, a Service Provider delivered public cloud, or a hybrid cloud environment – across the heterogeneous enterprise. In his session at 17th Cloud Expo, Randy De Meno, Chief Technologist - Windows Products and Microsoft Partnerships at Com...
Aug. 4, 2015 05:00 PM EDT Reads: 113
The Software Defined Data Center (SDDC), which enables organizations to seamlessly run in a hybrid cloud model (public + private cloud), is here to stay. IDC estimates that the software-defined networking market will be valued at $3.7 billion by 2016. Security is a key component and benefit of the SDDC, and offers an opportunity to build security 'from the ground up' and weave it into the environment from day one. In his session at 16th Cloud Expo, Reuven Harrison, CTO and Co-Founder of Tufin,...
Aug. 4, 2015 03:00 PM EDT Reads: 577
SYS-CON Events announced today that MobiDev, a software development company, will exhibit at the 17th International Cloud Expo®, which will take place November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. MobiDev is a software development company with representative offices in Atlanta (US), Sheffield (UK) and Würzburg (Germany); and development centers in Ukraine. Since 2009 it has grown from a small group of passionate engineers and business managers to a full-scale mobi...
Aug. 4, 2015 02:00 PM EDT Reads: 395
Between the compelling mockups and specs produced by your analysts and designers, and the resulting application built by your developers, there is a gulf where projects fail, costs spiral out of control, and applications fall short of requirements. In his session at @DevOpsSummit, Charles Kendrick, CTO and Chief Architect at Isomorphic Software, presented a new approach where business and development users collaborate – each using tools appropriate to their goals and expertise – to build mocku...
Aug. 4, 2015 01:30 PM EDT Reads: 106
SYS-CON Events announced today that VividCortex, the monitoring solution for the modern data system, will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. The database is the heart of most applications, but it’s also the part that’s hardest to scale, monitor, and optimize even as it’s growing 50% year over year. VividCortex is the first unified suite of database monitoring tools specifically desi...
Aug. 4, 2015 12:00 PM EDT Reads: 117
As Marc Andreessen says software is eating the world. Everything is rapidly moving toward being software-defined – from our phones and cars through our washing machines to the datacenter. However, there are larger challenges when implementing software defined on a larger scale - when building software defined infrastructure. In his session at 16th Cloud Expo, Boyan Ivanov, CEO of StorPool, provided some practical insights on what, how and why when implementing "software-defined" in the datacent...
Aug. 4, 2015 11:30 AM EDT Reads: 125
Learn how you can use the CoSN SEND II Decision Tree for Education Technology to make sure that your K–12 technology initiatives create a more engaging learning experience that empowers students, teachers, and administrators alike.
Aug. 4, 2015 09:30 AM EDT Reads: 123
Mobile, social, Big Data, and cloud have fundamentally changed the way we live. “Anytime, anywhere” access to data and information is no longer a luxury; it’s a requirement, in both our personal and professional lives. For IT organizations, this means pressure has never been greater to deliver meaningful services to the business and customers.
Aug. 4, 2015 08:45 AM EDT Reads: 265
"We've just seen a huge influx of new partners coming into our ecosystem, and partners building unique offerings on top of our API set," explained Seth Bostock, Chief Executive Officer at IndependenceIT, in this SYS-CON.tv interview at 16th Cloud Expo, held June 9-11, 2015, at the Javits Center in New York City.
Aug. 3, 2015 11:00 PM EDT Reads: 710
SYS-CON Events announced today that HPM Networks will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. For 20 years, HPM Networks has been integrating technology solutions that solve complex business challenges. HPM Networks has designed solutions for both SMB and enterprise customers throughout the San Francisco Bay Area.
Aug. 3, 2015 06:45 PM EDT Reads: 561
Take the Long View with Digital Transformation By @IoT2040 | @ThingsExpo #IoT #M2M #API #Microservices #InternetOfThings
Digital Transformation is the ultimate goal of cloud computing and related initiatives. The phrase is certainly not a precise one, and as subject to hand-waving and distortion as any high-falutin' terminology in the world of information technology. Yet it is an excellent choice of words to describe what enterprise IT—and by extension, organizations in general—should be working to achieve. Digital Transformation means: handling all the data types being found and created in the organizat...
Aug. 2, 2015 06:00 PM EDT Reads: 1,150
Chuck Piluso presented a study of cloud adoption trends and the power and flexibility of IBM Power and Pureflex cloud solutions. Prior to Secure Infrastructure and Services, Mr. Piluso founded North American Telecommunication Corporation, a facilities-based Competitive Local Exchange Carrier licensed by the Public Service Commission in 10 states, serving as the company's chairman and president from 1997 to 2000. Between 1990 and 1997, Mr. Piluso served as chairman & founder of International Te...
Aug. 2, 2015 04:00 PM EDT Reads: 454
With SaaS use rampant across organizations, how can IT departments track company data and maintain security? More and more departments are commissioning their own solutions and bypassing IT. A cloud environment is amorphous and powerful, allowing you to set up solutions for all of your user needs: document sharing and collaboration, mobile access, e-mail, even industry-specific applications. In his session at 16th Cloud Expo, Shawn Mills, President and a founder of Green House Data, discussed h...
Aug. 2, 2015 11:45 AM EDT Reads: 496
One of the hottest areas in cloud right now is DRaaS and related offerings. In his session at 16th Cloud Expo, Dale Levesque, Disaster Recovery Product Manager with Windstream's Cloud and Data Center Marketing team, will discuss the benefits of the cloud model, which far outweigh the traditional approach, and how enterprises need to ensure that their needs are properly being met.
Aug. 2, 2015 09:00 AM EDT Reads: 1,724
The Internet of Everything (IoE) brings together people, process, data and things to make networked connections more relevant and valuable than ever before – transforming information into knowledge and knowledge into wisdom. IoE creates new capabilities, richer experiences, and unprecedented opportunities to improve business and government operations, decision making and mission support capabilities.
Aug. 1, 2015 10:00 AM EDT Reads: 351
[slides] A New Architecture for the Internet of Things By @JKirklan | @ThingsExpo @RedHatNews #IoT #M2M #InternetOfThings
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at @ThingsExpo, James Kirkland, Red Hat's Chief Arch...
Jul. 30, 2015 07:30 PM EDT Reads: 1,438