Welcome!

Cloud Security Authors: Elizabeth White, John Walsh, James Carlini, Xenia von Wedel, Mehdi Daoudi

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

@ThingsExpo Stories
"Akvelon is a software development company and we also provide consultancy services to folks who are looking to scale or accelerate their engineering roadmaps," explained Jeremiah Mothersell, Marketing Manager at Akvelon, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
In his session at 21st Cloud Expo, Carl J. Levine, Senior Technical Evangelist for NS1, will objectively discuss how DNS is used to solve Digital Transformation challenges in large SaaS applications, CDNs, AdTech platforms, and other demanding use cases. Carl J. Levine is the Senior Technical Evangelist for NS1. A veteran of the Internet Infrastructure space, he has over a decade of experience with startups, networking protocols and Internet infrastructure, combined with the unique ability to it...
"Space Monkey by Vivent Smart Home is a product that is a distributed cloud-based edge storage network. Vivent Smart Home, our parent company, is a smart home provider that places a lot of hard drives across homes in North America," explained JT Olds, Director of Engineering, and Brandon Crowfeather, Product Manager, at Vivint Smart Home, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"IBM is really all in on blockchain. We take a look at sort of the history of blockchain ledger technologies. It started out with bitcoin, Ethereum, and IBM evaluated these particular blockchain technologies and found they were anonymous and permissionless and that many companies were looking for permissioned blockchain," stated René Bostic, Technical VP of the IBM Cloud Unit in North America, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Conventi...
Gemini is Yahoo’s native and search advertising platform. To ensure the quality of a complex distributed system that spans multiple products and components and across various desktop websites and mobile app and web experiences – both Yahoo owned and operated and third-party syndication (supply), with complex interaction with more than a billion users and numerous advertisers globally (demand) – it becomes imperative to automate a set of end-to-end tests 24x7 to detect bugs and regression. In th...
Large industrial manufacturing organizations are adopting the agile principles of cloud software companies. The industrial manufacturing development process has not scaled over time. Now that design CAD teams are geographically distributed, centralizing their work is key. With large multi-gigabyte projects, outdated tools have stifled industrial team agility, time-to-market milestones, and impacted P&L stakeholders.
"Cloud Academy is an enterprise training platform for the cloud, specifically public clouds. We offer guided learning experiences on AWS, Azure, Google Cloud and all the surrounding methodologies and technologies that you need to know and your teams need to know in order to leverage the full benefits of the cloud," explained Alex Brower, VP of Marketing at Cloud Academy, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clar...
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.
"MobiDev is a software development company and we do complex, custom software development for everybody from entrepreneurs to large enterprises," explained Alan Winters, U.S. Head of Business Development at MobiDev, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Coca-Cola’s Google powered digital signage system lays the groundwork for a more valuable connection between Coke and its customers. Digital signs pair software with high-resolution displays so that a message can be changed instantly based on what the operator wants to communicate or sell. In their Day 3 Keynote at 21st Cloud Expo, Greg Chambers, Global Group Director, Digital Innovation, Coca-Cola, and Vidya Nagarajan, a Senior Product Manager at Google, discussed how from store operations and ...
"There's plenty of bandwidth out there but it's never in the right place. So what Cedexis does is uses data to work out the best pathways to get data from the origin to the person who wants to get it," explained Simon Jones, Evangelist and Head of Marketing at Cedexis, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that CrowdReviews.com has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5–7, 2018, at the Javits Center in New York City, NY. CrowdReviews.com is a transparent online platform for determining which products and services are the best based on the opinion of the crowd. The crowd consists of Internet users that have experienced products and services first-hand and have an interest in letting other potential buye...
SYS-CON Events announced today that Telecom Reseller has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. Telecom Reseller reports on Unified Communications, UCaaS, BPaaS for enterprise and SMBs. They report extensively on both customer premises based solutions such as IP-PBX as well as cloud based and hosted platforms.
It is of utmost importance for the future success of WebRTC to ensure that interoperability is operational between web browsers and any WebRTC-compliant client. To be guaranteed as operational and effective, interoperability must be tested extensively by establishing WebRTC data and media connections between different web browsers running on different devices and operating systems. In his session at WebRTC Summit at @ThingsExpo, Dr. Alex Gouaillard, CEO and Founder of CoSMo Software, presented ...
WebRTC is great technology to build your own communication tools. It will be even more exciting experience it with advanced devices, such as a 360 Camera, 360 microphone, and a depth sensor camera. In his session at @ThingsExpo, Masashi Ganeko, a manager at INFOCOM Corporation, introduced two experimental projects from his team and what they learned from them. "Shotoku Tamago" uses the robot audition software HARK to track speakers in 360 video of a remote party. "Virtual Teleport" uses a multip...
A strange thing is happening along the way to the Internet of Things, namely far too many devices to work with and manage. It has become clear that we'll need much higher efficiency user experiences that can allow us to more easily and scalably work with the thousands of devices that will soon be in each of our lives. Enter the conversational interface revolution, combining bots we can literally talk with, gesture to, and even direct with our thoughts, with embedded artificial intelligence, whic...
SYS-CON Events announced today that Evatronix 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. Evatronix SA offers comprehensive solutions in the design and implementation of electronic systems, in CAD / CAM deployment, and also is a designer and manufacturer of advanced 3D scanners for professional applications.
Leading companies, from the Global Fortune 500 to the smallest companies, are adopting hybrid cloud as the path to business advantage. Hybrid cloud depends on cloud services and on-premises infrastructure working in unison. Successful implementations require new levels of data mobility, enabled by an automated and seamless flow across on-premises and cloud resources. In his general session at 21st Cloud Expo, Greg Tevis, an IBM Storage Software Technical Strategist and Customer Solution Architec...
To get the most out of their data, successful companies are not focusing on queries and data lakes, they are actively integrating analytics into their operations with a data-first application development approach. Real-time adjustments to improve revenues, reduce costs, or mitigate risk rely on applications that minimize latency on a variety of data sources. In his session at @BigDataExpo, Jack Norris, Senior Vice President, Data and Applications at MapR Technologies, reviewed best practices to ...
An increasing number of companies are creating products that combine data with analytical capabilities. Running interactive queries on Big Data requires complex architectures to store and query data effectively, typically involving data streams, an choosing efficient file format/database and multiple independent systems that are tied together through custom-engineered pipelines. In his session at @BigDataExpo at @ThingsExpo, Tomer Levi, a senior software engineer at Intel’s Advanced Analytics gr...