Welcome!

Java IoT Authors: Xenia von Wedel, Pat Romanski, Liz McMillan, John Esposito, Elizabeth White

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

SDN Journal: Blog Post

What SDN Can Do for Multicast Topologies

IP Multicast is one of those technologies that most everyone loves to hate

IP Multicast is one of those technologies that most everyone loves to hate. It’s almost the perfect example of how complicated we have made networking. Getting IP Multicast to run depends on several protocols that are all somewhat intertwined or dependent on each, their relationship sometimes explicit, sometimes implicit.

Even trying to describe the basic operation is complicated.

When an application or service provides information using IP multicast, it simply starts sending it onto a specific multicast group. The multicast router for the subnet of the sender sees the incoming multicast packet and will initially have no forwarding information for that stream in its forwarding hardware. The packet is passed onto the CPU of that router, which will encapsulate this packet and send it towards a special multicast router designated the Rendez-vous Point (RP). When the RP has installed the multicast routes for this group, it will tell the multicast router on the sender’s segment to stop sending. When it does, this router installs its own multicast routes for the source tree (the tree specific to this sender) and the shared tree (the one towards the RP) without any outgoing interfaces, and the traffic is dropped at this first router. But, the network (well at least the part between the sender and the RP) is now aware of this multicast stream. And who is sending.

Now when we want to join this IP Multicast group, the first action is send an IGMP join out on the subnet you are attached to. The IP Multicast router that serves this subnet sees the join and determines where RP can be found. It takes the client join, and sends it towards the RP, using the unicast routing table as its guide. Every multicast router along the way registers that there is a listener on the interface this join came in on and passes it along towards the IP. All along this path, the unicast routing entry for the RP is used to create the tree towards the listener.

Once received by the RP, the shared tree and the source tree towards the sender have been joined. We have an end to end path between sender and receiver, with the RP in the middle of it all. All that is left is to send a join from the RP towards the router on the sender’s subnet to essentially tell it to start passing the actual multicast along the path towards the RP (the source tree), where the RP will then push it out onto the shared tree towards the destination. Voila, it’s as simple as that.

But wait, we are not done. Once the packets start to flow from source to destination, the multicast router closest to the destination will send another join message for this group, but this time towards the sender. It is only now that it can do this because those first few data packets actually indicate who the sender is. That join is passed router to router to router towards the router on the sender’s subnet, and once arrived, that router will now also start sending the multicast data along that path towards the receiver. The receiving subnet router sees that stream appearing and will now send a prune message onto the shared tree towards the RP, indicating it no longer needs the multicast stream through the RP.

If you are not familiar with IP Multicast and after reading the above are not confused, congratulations, your brain is very well wired for complex networking.

If you step away from how IGMP and PIM implement this today as above, the most fundamental of IP multicast topologies is that you need to build a forwarding tree that is rooted in the source, with the destinations as its leaves. At each intermediate node in the tree, the packets are replicated to its branches, therefore creating the least amount of duplication. And by using a tree, it is loop free, packets won’t swirl around the network bringing it to its knees.

The challenging part though is that the tree is based on the unicast forwarding topology. From a leaf on this tree towards the sender, each step is identical to how a unicast IP packet would be forwarded. The forwarding topologies are connected and dependent on each other. IP Multicast is built on top of a unicast routed infrastructure, and unicast routing changes can have dramatic impacts to the multicast forwarding topologies.

I mentioned here before that I once spent a wonderful 2 weeks in Delhi working on a network where surveillance cameras created an aggregate 8Gbit/sec worth of multicast data, with a requirement that any unicast change would have limited impact to these streams. Believe me, it is extremely hard to engineer and tune, and we had the luxury of hijacking a really large network night after night to simulate failures.

SDN based architectures have the opportunity to change all this. Multicast forwarding was designed the way it was designed to work on arbitrary network topologies, with random senders and receivers coming and going. It builds trees on the fly and on demand. For many networks, topologies are not arbitrary, and those applications that consume/produce lots of multicast do not have randomly placed senders and receivers that come and go as they please.  Many of them are well known or placed in fairly static and fixed topologies.

A controller with a global view of the network can create multicast topologies ahead of time. It knows all possible replication points and can create distribution trees among them. It can create different distribution trees for different multicast groups. It can create them independent of the unicast forwarding. It can calculate backup topologies in case portions of the tree fail. And it can do all of that guaranteeing there are no loops and optimal replication. When applications indicate their participation in specific multicast streams as senders or listeners to this controller, it can optimize very specifically based on those participants. The possibilities are endless.

We had a customer visit us yesterday that has very significant multicast needs and we walked him through some of these possibilities. He left with a huge smile on his face. And that smile on his face was not because he really liked what we built (even though he did), but it was because we showed him that if you remove legacy network thinking and constraints, networking can yet again be extremely exciting and creates solutions that he did not think were possible, in a fairly simple and straightforward way. And that, in turn, is truly exciting to us.

The post What SDN can do for Multicast Topologies appeared first on Plexxi.

Read the original blog entry...

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
In his keynote at 18th Cloud Expo, Andrew Keys, Co-Founder of ConsenSys Enterprise, provided an overview of the evolution of the Internet and the Database and the future of their combination – the Blockchain. Andrew Keys is Co-Founder of ConsenSys Enterprise. He comes to ConsenSys Enterprise with capital markets, technology and entrepreneurial experience. Previously, he worked for UBS investment bank in equities analysis. Later, he was responsible for the creation and distribution of life sett...
Basho Technologies has announced the latest release of Basho Riak TS, version 1.3. Riak TS is an enterprise-grade NoSQL database optimized for Internet of Things (IoT). The open source version enables developers to download the software for free and use it in production as well as make contributions to the code and develop applications around Riak TS. Enhancements to Riak TS make it quick, easy and cost-effective to spin up an instance to test new ideas and build IoT applications. In addition to...
There are several IoTs: the Industrial Internet, Consumer Wearables, Wearables and Healthcare, Supply Chains, and the movement toward Smart Grids, Cities, Regions, and Nations. There are competing communications standards every step of the way, a bewildering array of sensors and devices, and an entire world of competing data analytics platforms. To some this appears to be chaos. In this power panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, Bradley Holt, Developer Advocate a...
Presidio has received the 2015 EMC Partner Services Quality Award from EMC Corporation for achieving outstanding service excellence and customer satisfaction as measured by the EMC Partner Services Quality (PSQ) program. Presidio was also honored as the 2015 EMC Americas Marketing Excellence Partner of the Year and 2015 Mid-Market East Partner of the Year. The EMC PSQ program is a project-specific survey program designed for partners with Service Partner designations to solicit customer feedbac...
Connected devices and the industrial internet are growing exponentially every year with Cisco expecting 50 billion devices to be in operation by 2020. In this period of growth, location-based insights are becoming invaluable to many businesses as they adopt new connected technologies. Knowing when and where these devices connect from is critical for a number of scenarios in supply chain management, disaster management, emergency response, M2M, location marketing and more. In his session at @Th...
The cloud market growth today is largely in public clouds. While there is a lot of spend in IT departments in virtualization, these aren’t yet translating into a true “cloud” experience within the enterprise. What is stopping the growth of the “private cloud” market? In his general session at 18th Cloud Expo, Nara Rajagopalan, CEO of Accelerite, explored the challenges in deploying, managing, and getting adoption for a private cloud within an enterprise. What are the key differences between wh...
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, wh...
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....
SYS-CON Events announced today that Bsquare has been named “Silver Sponsor” of SYS-CON's @ThingsExpo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. For more than two decades, Bsquare has helped its customers extract business value from a broad array of physical assets by making them intelligent, connecting them, and using the data they generate to optimize business processes.
Internet of @ThingsExpo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 19th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago. All major researchers estimate there will be tens of billions devices - comp...
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...
It is one thing to build single industrial IoT applications, but what will it take to build the Smart Cities and truly society changing applications of the future? The technology won’t be the problem, it will be the number of parties that need to work together and be aligned in their motivation to succeed. In his Day 2 Keynote at @ThingsExpo, Henrik Kenani Dahlgren, Portfolio Marketing Manager at Ericsson, discussed how to plan to cooperate, partner, and form lasting all-star teams to change t...
The 19th International Cloud Expo has announced that its Call for Papers is open. Cloud Expo, to be held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, brings together Cloud Computing, Big Data, Internet of Things, DevOps, Digital Transformation, Microservices and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding business opportuni...
Internet of @ThingsExpo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with the 19th International Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world and ThingsExpo Silicon Valley Call for Papers is now open.
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...
In his general session at 18th Cloud Expo, Lee Atchison, Principal Cloud Architect and Advocate at New Relic, discussed cloud as a ‘better data center’ and how it adds new capacity (faster) and improves application availability (redundancy). The cloud is a ‘Dynamic Tool for Dynamic Apps’ and resource allocation is an integral part of your application architecture, so use only the resources you need and allocate /de-allocate resources on the fly.
Machine Learning helps make complex systems more efficient. By applying advanced Machine Learning techniques such as Cognitive Fingerprinting, wind project operators can utilize these tools to learn from collected data, detect regular patterns, and optimize their own operations. In his session at 18th Cloud Expo, Stuart Gillen, Director of Business Development at SparkCognition, discussed how research has demonstrated the value of Machine Learning in delivering next generation analytics to imp...
Cognitive Computing is becoming the foundation for a new generation of solutions that have the potential to transform business. Unlike traditional approaches to building solutions, a cognitive computing approach allows the data to help determine the way applications are designed. This contrasts with conventional software development that begins with defining logic based on the current way a business operates. In her session at 18th Cloud Expo, Judith S. Hurwitz, President and CEO of Hurwitz & ...
SYS-CON Events announced today that ReadyTalk, a leading provider of online conferencing and webinar services, has been named Vendor Presentation Sponsor 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. ReadyTalk delivers audio and web conferencing services that inspire collaboration and enable the Future of Work for today’s increasingly digital and mobile workforce. By combining intuitive, innovative tec...
Amazon has gradually rolled out parts of its IoT offerings, but these are just the tip of the iceberg. In addition to optimizing their backend AWS offerings, Amazon is laying the ground work to be a major force in IoT - especially in the connected home and office. In his session at @ThingsExpo, Chris Kocher, founder and managing director of Grey Heron, explained how Amazon is extending its reach to become a major force in IoT by building on its dominant cloud IoT platform, its Dash Button strat...