Welcome!

Cloud Expo Authors: Yeshim Deniz, Greg Ness, Elizabeth White, Pat Romanski, Carmen Gonzalez

Related Topics: SDN Journal, Java, Linux, Virtualization, Cloud Expo, Security

SDN Journal: Blog Feed Post

SDN Prerequisite: Stateful vs Stateless

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

We've talked before about the bifurcation of the network, which is driven as much by the evolution of network services from "nice to have" to "critical" as it is by emerging architectures. The demarcation line in the network stack has traditionally been - and remains - between layers 3 and 4 in the OSI model. The reason for this is that there is a transition as you move from layer 3 to layer 4 from stateless networking to stateful networking.

bifurcated-network-stateful-statelessThis is important to emerging architectures like SDN because this characteristic determines what level of participation in the data path is required.

Stateless networking requires very little participation. It's limited to evaluating network protocol frames and headers for the purpose of determining where to forward any given packet. The information extracted from the packet is not saved; it is not compared to previous packets.This is why it's stateless, because no information regarding the state of the communication is retained. It is evaluated and the packet is forwarded out the appropriate port based on what's in the FIB (Forwarding Information Base) or what's more commonly referred to as the "forwarding table."

Stateful networking, which begins at layer 4, retains certain information extracting from frames and packets and, as you move up the stack, from the application layer. It does this because protocols like TCP are connection-oriented and try to maintain guaranteed delivery. This is achieved through the use of sequence numbers in the TCP headers that, when out of order or lost cause the network to retransmit the packets.

There is state associated with TCP, i.e. "I have received packet 1 and am waiting for packet 2 in this connection." This is readily seen in the use of ACKnowledgment packets associated with TCP. There is a pre-designated flow associated with TCP that depends on the state of the end-points involved in the connection.

tcp-conversation-2

When a networking service operating at layer 4 or higher is inserted into this communication flow, it must also maintain the connection state. This is particularly true of staple stateful services such as security and load balancing, which rely on state to provide stateful failover services (i.e., without simply dropping connections) or to detect attacks based on state, such as SYN floods.

The higher a network service operates in the network stack, the more participation is required. For example, application routing based on HTTP headers (the URI, the hostname, cookie values, etc... ) rely on the ability of an intermediate network device maintaining state as well as extracting data from within the payload of a message (which is not the same as a packet). A message might actually require 2 or 3 or more packets, as data transferred by modern web applications is often larger than the network MTU of 1500 bytes. This means the intermediate device operating at the application layer must be stateful, as it must act as the end point for the connection in order gather all the packets that make up a message before it can extract the data and then execute its policies. This is why we also emphasize that layer 2-3 is "fixed" and layer 4-7 is "variable."

Networking protocols at layer 2-3 are governed by standards that clearly define the layout of Ethernet frames and IP packets. Devices operating at those layers have highly optimized algorithms for extracting the information needed from frames and packet headers in order to determine how to forward the packet. TCP affords the same luxury at layer 4, but as networking moves up the stack the exactly location of information necessary to make a forwarding decision become highly variable.

Even with a clearly defined protocol like HTTP, there is a wide variation in where certain data might be in the header. This is because not all headers are required and unlike Ethernet and IP and even TCP, where options may not be specified, there is still room reserved for those values. HTTP does not require that space be reserved for optional headers. They are simply left out, which can dramatically change the location (and thus the method of extraction by the intermediate device) of the data necessary to formulate a forwarding decision.

Say you had a form to fill out and, depending on the answer to question 2 you might go on to question 3 or skip to question 8. If that form were layer 2 or 3, each question would be clearly numbered. Skipping to question 8 would be quick and easy. But if that form were layer 7, the questions are not labeled, and to get to question 8 you have to count each of the questions manually. That's the difference between "fixed" and "variable". It's why compute resource requirements are more important to layer 7 than they are to layer 2 or 3.

Why this matters to SDN

This matters a great deal to SDN architectures because of how it impacts the control-data plane separation architecture. Stateless networking is perfectly suited to an architecture that places responsibility for making forwarding decisions on a centralized controller because the frequency with which those decisions must be made is relatively low. Conversely, stateful networking requires more participation and more frequent decisions as well as requiring the maintenance of state for each and every connection. This has serious implications for the controller in such a model, as it forces issues of controller scalability and resource requirements into the equation as the controller more actively participates (and stores more information) with stateful networking than it does with stateless networking.

This is not to say that SDN architecture is incompatible with higher order network services. It just means that the SDN solution you choose for stateless networking will almost certain not be the same SDN solution you choose for stateful networking. That means it's important to investigate solutions that address both of your "networks" with an eye toward integration and interoperability.

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
The definition of IoT is not new, in fact it’s been around for over a decade. What has changed is the public's awareness that the technology we use on a daily basis has caught up on the vision of an always on, always connected world. If you look into the details of what comprises the IoT, you’ll see that it includes everything from cloud computing, Big Data analytics, “Things,” Web communication, applications, network, storage, etc. It is essentially including everything connected online from ha...
We are all here because we are sold on the transformative promise of The Cloud. But what good is all of this ephemeral, on-demand infrastructure if your usage doesn't actually improve the agility and speed of your business? How must Operations adapt in order to avoid stifling your Cloud initiative? In his session at DevOps Summit, Damon Edwards, co-founder and managing partner of the DTO Solutions, will highlight the successful organizational, process, and tooling patterns of high-performing c...
Software-driven innovation is becoming a primary approach to how businesses create and deliver new value to customers. A survey of 400 business and IT executives by the IBM Institute for Business Value showed businesses that are more effective at software delivery are also more profitable than their peers nearly 70 percent of the time (1). DevOps provides a way for businesses to remain competitive, applying lean and agile principles to software development to speed the delivery of software that ...
Docker offers a new, lightweight approach to application portability. Applications are shipped using a common container format and managed with a high-level API. Their processes run within isolated namespaces that abstract the operating environment independently of the distribution, versions, network setup, and other details of this environment. This "containerization" has often been nicknamed "the new virtualization." But containers are more than lightweight virtual machines. Beyond their small...
The move in recent years to cloud computing services and architectures has added significant pace to the application development and deployment environment. When enterprise IT can spin up large computing instances in just minutes, developers can also design and deploy in small time frames that were unimaginable a few years ago. The consequent move toward lean, agile, and fast development leads to the need for the development and operations sides to work very closely together. Thus, DevOps become...
Cloud Expo 2014 TV commercials will feature @ThingsExpo, which was launched in June, 2014 at New York City's Javits Center as the largest 'Internet of Things' event in the world.

ARMONK, N.Y., Nov. 20, 2014 /PRNewswire/ --  IBM (NYSE: IBM) today announced that it is bringing a greater level of control, security and flexibility to cloud-based application development and delivery with a single-tenant version of Bluemix, IBM's

An entirely new security model is needed for the Internet of Things, or is it? Can we save some old and tested controls for this new and different environment? In his session at @ThingsExpo, New York's at the Javits Center, Davi Ottenheimer, EMC Senior Director of Trust, reviewed hands-on lessons with IoT devices and reveal a new risk balance you might not expect. Davi Ottenheimer, EMC Senior Director of Trust, has more than nineteen years' experience managing global security operations and asse...
The major cloud platforms defy a simple, side-by-side analysis. Each of the major IaaS public-cloud platforms offers their own unique strengths and functionality. Options for on-site private cloud are diverse as well, and must be designed and deployed while taking existing legacy architecture and infrastructure into account. Then the reality is that most enterprises are embarking on a hybrid cloud strategy and programs. In this Power Panel at 15th Cloud Expo (http://www.CloudComputingExpo.com...
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 Internet of @ThingsExpo, James Kirkland, Chief Ar...
Leysin American School is an exclusive, private boarding school located in Leysin, Switzerland. Leysin selected an OpenStack-powered, private cloud as a service to manage multiple applications and provide development environments for students across the institution. Seeking to meet rigid data sovereignty and data integrity requirements while offering flexible, on-demand cloud resources to users, Leysin identified OpenStack as the clear choice to round out the school's cloud strategy. Additional...
The security devil is always in the details of the attack: the ones you've endured, the ones you prepare yourself to fend off, and the ones that, you fear, will catch you completely unaware and defenseless. The Internet of Things (IoT) is nothing if not an endless proliferation of details. It's the vision of a world in which continuous Internet connectivity and addressability is embedded into a growing range of human artifacts, into the natural world, and even into our smartphones, appliances, a...
Technology is enabling a new approach to collecting and using data. This approach, commonly referred to as the "Internet of Things" (IoT), enables businesses to use real-time data from all sorts of things including machines, devices and sensors to make better decisions, improve customer service, and lower the risk in the creation of new revenue opportunities. In his General Session at Internet of @ThingsExpo, Dave Wagstaff, Vice President and Chief Architect at BSQUARE Corporation, discuss the ...
"BSQUARE is in the business of selling software solutions for smart connected devices. It's obvious that IoT has moved from being a technology to being a fundamental part of business, and in the last 18 months people have said let's figure out how to do it and let's put some focus on it, " explained Dave Wagstaff, VP & Chief Architect, at BSQUARE Corporation, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4-6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
The 4th International DevOps Summit, co-located with16th International Cloud Expo – being held June 9-11, 2015, at the Javits Center in New York City, NY – announces that its Call for Papers is now 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 large...
Verizon Enterprise Solutions is simplifying the cloud-purchasing experience for its clients, with the launch of Verizon Cloud Marketplace, a key foundational component of the company's robust ecosystem of enterprise-class technologies. The online storefront will initially feature pre-built cloud-based services from AppDynamics, Hitachi Data Systems, Juniper Networks, PfSense and Tervela. Available globally to enterprises using Verizon Cloud, Verizon Cloud Marketplace provides a one-stop shop fo...
"Our premise is Docker is not enough. That's not a bad thing - we actually love Docker. At ActiveState all our products are based on open source technology and Docker is an up-and-coming piece of open source technology," explained Bart Copeland, President & CEO of ActiveState Software, in this SYS-CON.tv interview at DevOps Summit at Cloud Expo®, held Nov 4-6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
DevOps Summit 2015 New York, co-located with the 16th International Cloud Expo - to be held June 9-11, 2015, at the Javits Center in New York City, NY - announces that it is now accepting Keynote Proposals. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait for long development cycles that produce software that is obsolete...
Infor has announced a new feature Infor CloudSuite™ Aerospace & Defense (A&D) to aid compliance with International Traffic in Arms Regulations (ITAR). The ITAR function will serve as a complementary function for new or existing Infor CloudSuite A&D customers, to facilitate compliance for Infor customers that are creating a US defense article or performing a US defense service and wish to benefit from cloud-services. The ITAR regulation serves to manage handling and access requirements for dat...
What do a firewall and a fortress have in common? They are no longer strong enough to protect the valuables housed inside. Like the walls of an old fortress, the cracks in the firewall are allowing the bad guys to slip in - unannounced and unnoticed. By the time these thieves get in, the damage is already done and the network is already compromised. Intellectual property is easily slipped out the back door leaving no trace of forced entry. If we want to reign in on these cybercriminals, it's hig...