Archive for the ‘Uncategorized’ Category

Re-blogging the entry I just posted on the Open Networking Summit and our RouteFlow demo:

RouteFlow demo at ONS

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At CPqD and together with the University of Campinas, we are working on a line of research that tries to marry open source routing software (Quagga) with programmable switches (OpenFlow).

OpenFlow is an initiative lead by Stanford University to open up networking devices (switches, routers, access points, base stations) by defining a standard protocol to define the packet forwarding actions. The main abstraction consists of a flow — though the flow table abstraction is still subject to refinements to best expose actual hardware resources — basically formed by any combination among a dozen pieces of information forming the context (i.e., packet header fields up to the transport layer plus incoming port) of a packet to be handled by a device.
You can find more details reading the current specification or the multiple academic papers on OpenFlow. Or even better, put your hands on OpenFlow by following this tutorial (recently held by Stanford people in the major distributed systems Brazilian conference).

OpenFlow is certainly not the first approach to enable some degree of network programmability — the so sought holly grail of network infrastructure providers. Related work can be dated back to the 90´s and the efforts in programming telecommunication networks, the OPENSIG community, IEEE 1520, MPOA (Multi-protocol over ATM), GSMP (General Switch Management Protocol) RFC3292, the active network research thread, and more recently work being done at IETF forces WG (Forwarding and Control Element Separation).

While the motivation behind all this body of work is more or less the same (enabling new features, lowering costs, new revenue streams, etc.). To my understanding, the fundamental difference of the OpenFlow approach is its pragmatism. OpenFlow does not aim at trying to satisfy everybody´s needs and a pragmatic way starts by trying to re-use existing hardware capabilities (e.g, ACL in switches and routers) and defining a simple set of matching rules and associated actions (e.g., forward, discard, send to controller, re-write header XYZ). This way, OpenFlow could be enabled on existing hardware by means of a firmware update. And more importantly, industry attention has been attracted and we can already buy OpenFlow-enabled equipment and prototypes from big players like Cisco, HP, NEC, Extreme, and Juniper are on their way to the product line.

We have called our work QuagFlow and will be presented as a poster in this year´s SIGCOMM edition in New Delhi. See a preview below.

QuagFlow Sigcomm poster quagga openflow

Now that we are progressing with our vision and implementation of QuagFlow, along more literature research, we regret not having cited in our poster version the work by Lakshman et al. at Bell/Lucent on the SoftRouter Architecture. We are coming to a design close to what the SoftRouter has been pursuing on separating control software from routers. Their approach is based on the ForCES protocol vs our OpenFlow interface. Its unclear to me how far their prototypical work has gone along these years. Would like very much to know, especially as we should expect to face a set of similar challenges along our journey.

Further Reading:


Computing history has shown that open, multi-layer hardware and software stacks encourage innovation and bringcosts down. Only recently this trend is meeting the net-working world with the availability of entire open source net-working stacks being closer than ever. Towards this goal, weare working on QuagFlow, a transparent interplay between the popular Quagga open source routing suite and the lowlevel vendor-independent OpenFlow interface. QuagFlow isa distributed system implemented as a NOX controller ap-plication and a series of slave daemons running along thevirtual machines hosting the Quagga routing instances.

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It was a great week in Bremen!
The Future Internet Summer School has met by far my expectations. Good organized, excellent talks, multi-cultural interactions, technical discussions, tasty beer, and so on.

You can find most of the presentations and course material online.

I want to point you to the insightful presentation by Van Jacobson on thr work at Xerox PARC on content-centric networking. The slides are online:

Special Invited Plenary Short Course: (CCN) Content Centric Networking by: Van Jacobson

and hopefully the video will be also available. In the large and content-dense talk (around 2,5 hs), Van provided many details of the CCN architecture, presenting the models for content, nodes, routing, security, and transport, unveiling the practical foundations of CCN. He answered many of the questions from the 2006 video, but at the same time opened lots of new questions….

UPDATE 16/07/2010:

Future Internet Summer School (FISS09) Short course

One of my points to take home is that CCN not only works over IP, without new infrastructure requirements, but also very important you could run IP over CCN, by considering host identifiers (IP) as the content-objects you request…

A content layer for the new Internet waist

A content layer for the new Internet waist


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infocom 09 in Rio

Last week I had the chance to participate in this year’s edition of the IEEE Infocom conferences in the “cidade maravilhosa” of Rio de Janeiro!

Great location, great technical program, and great panel discussion and keynotes. The first day there was an excellent tutorial on sensor networks by Jim Kurose, free of charge thanks to the conference sponsors!

From the panel on Clean Slate Architectures: Where Are We Today, And What Is The Path Forward?

My opinion on clean slate research continues the same: it does not presume clean slate deployment and aims at innovation through questioning the fundamentals withou the constraints of the currently deployed architecture. Recommended introductory reading by Prof. A. Feldman: Internet Clean-Slate Design: What and Why? and my information-centric perspective to future Internet design:

More to take home from Infocom (besides the papers, the promotional books by Pearson, and the calories from the churrascaria “Porcao”):


And from my notes of the panel on What Are The Hot Topics in Networking?

Prof. Keith Ross was IMO the one who pointed out the two most interesting trends (I am not that into wireless currently):

1.- The marriage of social networks and P2P: How to enrich / enhance p2p overlays with existing social networks to exploit, proximity, trust and security?

2.- Data center networking: A lot to do to in terms of architecting the large energy-hungry networking infrastructure of data centers. Splitting TCP connections at the front-end, load balancing, intelligent wiring, cost reduction, avoiding bottlenecks (network and I/O), etc… I hope his ppt will be available soon online. Look at SIGCOMM 2008 papers on data center designs to see what kind of research is going on, and more papers in this line are expected in this year’s SIGCOMM.

There was lots of discussion on what are good topics for PhD research. Confirming some of my late suspects, and in contradiction to my previous post on network coding, network coding was considered a topic losing temperature. The practical / killer deployments are not emerging, and for wired scenarios the applications of pure network coding are still yet to be proven effective and efficient to be worth.

For more on cold topics in network: Jon Crowcroft, “Cold Topics in Networking”

and by googling for the link I found a promising material of a recent workshop held by Jon Crowcroft covering research issues and methodology.

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Research on happiness

I just watched a TED talk from Dan Gilbert (Psychologist; happiness expert) on his research work around “happiness”.  In a funny and insightful talk Dan explains the human behaviour around happiness and provides counter intuitive examples. 

Don´t miss his videos on TED if you want to understand:

  • the answer on what makes you fell happy or
  • why we do not feel miserable if we don’t get what we want,
  • is there a “synthetic” happiness,
  • the psychological immune system work
  • and more…
 Dan Gilbert researches happiness

Dan Gilbert asks, Why are we happy?     
TED Talks Dan Gilbert, author of Stumbling on Happiness, challenges the idea that we’ll be miserable if we don’t get what we want.


In a previous post on good content I suggested another video from TED, again one psychologist unveiling our daily human behaviour:

Barry Schwartz on the paradox of choice | Video on TED.com
  • TED Talks Psychologist Barry Schwartz takes aim at a central belief of western societies: that freedom ofchoice leads to personal happiness.

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In the digital-intense world we are living, one could argue that there is decreasing tendency in consuming content and sharing information in the form of traditional paper books. At the same time, my experience in consuming books in audio form (audible.com) and eBook pdfs (did no tried yet the Amazon Kindle or the Sony e-reader) has been very positive! I specially like the audio formats for my commutes, supermarket, administrative queues and outside jogging. I have heard great reviews about the Kindle 2, I hope it will be soon available outside the US, if not, I may consider to buy it anyways if  it is usable without the US wireless infrastructure…

In this post, I just want to share some of the latest books (from multiple disciplines) I have “consumed” and can really recommend:


An ”outlier” is a super-achiever, like Bill Gates, the Beatles and many others. The author unveils hidden factors that make people extremely successful, with compelling arguments and contradicting the readers’ intuition many times during the nice storyline.  You will find ou how important can be where and when you were born (e.g., premier league athletes mostly born in the first quarter of a year, IT billionaires like Jobs or Gates born around 1955), or why are Asians so good at math (spoiler: it is not in the genes)? This book recalls me another excellent common believe breaker: 


–  Brain Rules: 12 Principles for Surviving and Thriving at Work, Home, and School by John J., Ph.D. Medina

Network Coding Applications by Christina Fragouli and Emina Soljanin 

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Continuing the enterprise of research in re-architecting the future Internet, I have started to delve into the world of “network coding”, a recent field of study (Ahlswede, 2000) that aims at solving an “information flow problem”
by leveraging forwarding nodes in a network with “content mixing” capabilities of data flows (packets) in addition to simply forwarding operations.

Even though the practical usage of network coding has yet to be proven in many real networking scenarios, network coding is being considered by major research industry players as part of  the next wave of networking.

The promise of network coding? Gains in terms of network throughput, resilience, security, simplicity… an alternative path to the current practices of boosting network performance, which is basically limited on new networking hardware versions with increased chip rate and memory sizes. 

In my opinion, network coding applied to future inter-networking architectures is an example of research by questioning paradigms and has the potential to introduce another shift in internetworking with an impact comparable to the information theory work of Shannon 60 years ago.

In this post, I will not introduce gratuitous maths and non-rigorous explanation on network coding (please refer to the wast
literature, specially a book for theoreticians and and another one for practitioners). The point I want to make is some key observations that make me believe that network coding is an area worth of exploring for any future networking research project:

  • Big computer industry players (e.g., Microsoft, HP, Intel) are investing in network-coding applied research. There may be something ($$$) beyond pure academic research.
  • Pioneering research institutions around the world (e.g., Berkeley, MIT) are increasingly publishing the practical results of ongoing research projects.
  • Network coding is meeting legacy network settings, e.g., the TCP protocol (Sundajaran et al, INFOCOM ’09). We may see further “transparent” integration of network coding in real systems.

So far, so good. But, network coding is a tricky area. Even though it’s basic concept and the canonical example over a butterfly type of network is pretty simple, the actual field where network coding can be apply and the implementation options is very broad, spanning over all the layers of the traditional network stack:

I admit a taxonomy based on layers is blury below the network level, where “practical network coding” by Chou et al introduced the notion of mixing packets within generations.

Skepticism is also there (How Practical is Network Coding?). Or should I say good sense (Mixing PacketsPros and Cons of Network Coding”). We may assist to some phase of delusion surrounding network coding, if a typical Gartner’s hype cycle can be applied to the field of research.

Gartner's hype cycle

Question to the community? In which phase would you say is network coding (if research were a technology product)?

  1. “Technology Trigger”
  2. “Peak of Inflated Expectations”
  3. “Trough of Disillusionment”

I have my own list of questions when thinking about the practicality (implementability) of network coding:

  • How to decide which information to mix when operating over multiple flows?
  • How to carry effciently the coding operations to the final data consumers?
  • How to achieve butterfly type of network paths in the information-oriented network under sonsideration?
  • Differences and similitudes of network coding over wireless networks compared to wired deployments?
  • Feedback channel and applicability in two-way communications (real and non-real time)?
  • Security advantages and implications of network coding?
  • Interactions with active caching functionalities at multiple levels (packets, pages, documents)?

I will start thinking small, listing the requirements (e.g., multi-paths, identifier space, meaningfulness of packet generation, packet
headers) to perform a strawman approach for network coding in the context of information-oriented networking (e.g., the PSIRP project). Then, we can evaluate the costs and the practical benefits by extensive ns-3 simulations and may be some NetFPGA test implementations.

Whether network coders will eventually supplant routers in large, shared infrastructures like the Internet is very questionable, may be
in the long term as an additional network service… However, I think that we will se more and more real life (niche?) solutions implementing some flavour of network coding. Let it be an IPTV multicast deployment, or Instant Messaging dissemination protocols, error correction algorithms, switch designs or new variants of P2Pcontent distribution schemes like Microsoft’s Avalanche…

I am curious if Rudolf Ahlswede of the University of Bielefeld, Germany could imagine the impact of his research back in
2000. In this post, I have raised more questions than answers. Hopefully, I can turn this over during this promising 2009.

To end with, an optimistic quote of network coding experts:

“By changing how networks function, network coding may influence society in ways we cannot yet imagine.”



P.D: I found another optimistic (press-type) reference related to the information-oriented research area: PcMag includes the Van Jacobsen’s content-centric networking (CCN) as one of the “five ideas that will reinvent modern computing“, although I dislike very much the term “Extreme Peer-to-Peer” used by the PcMAg redactors.

P.D2: I could not resist not to google what the blogsphere has also commented on this topic:

Back to Research: Network Coding and a Small Riddle for You
Network Coding for Mobile Phones
– Do you know more?
Selected publications on network coding:

  • Network Information Flow. R. Ahlswede, N. Cai, S.-Y. R. Li and R. W. Yeung in IEEE Transactions on Information Theory, Vol. 46, No. 4, pages 1204-1216; July 2000.
  • T. Ho and D. S. Lun. “Network Coding: An Introduction. Cambridge University Press, Cambridge, U.K., April 2008.
  • Fragouli, C. and Soljanin, E. 2007. Network coding applications. Found. Trends Netw. 2, 2 (Jan. 2007), 135-269. DOI= http://dx.doi.org/10.1561/1300000013
  • Information Theory and Network Coding by Raymond W. Yeung, The Chinese University of Hong Kong, Springer, August 2008
  • Linear Network Coding. S.-Y. R. Li, R. W. Yeung and N. Cai in IEEE Transactions on Information Theory, Vol. 49, No. 2, pages 371-381; February 2003.
  • An Algebraic Approach to Network Coding. R. Koetter and M. M?dard in IEEE/ACM Transactions on Networking, Vol. 11, No. 5, pages 782-795; October 2003.
  • Polynomial Time Algorithms for Multicast Network Code Construction. S. Jaggi, P. Sanders, P. A. Chou, M. Effros, S. Egner, K. Jain and L.M.G.M. Tolhuizen in IEEE Transactions on Information Theory, Vol. 51, No. 6, pages 1973-1982; June 2005.
  • T. Ho, M. Medard, R. Koetter, D. R. Karger, M. Effros, J. Shi and B. Leong. A Random Linear Network Coding Approach to Multicast. In IEEE Transactions on Information Theory, Vol. 52, No. 10, pages 4413-4430; October 2006.
  • Jay Kumar Sundararajan and Devavrat Shah and Muriel Medard and Michael Mitzenmacher and João Barros. Network coding meets TCP. CoRR, (abs/0809.5022) 2008. [BibSonomy: dblp] URL
  • P. Chou, Y. Wu, and K. Jain, “Practical network coding,” 2003. [Online]. Available: http://citeseer.ist.psu.edu/chou03practical.html
  • Barros, J.; “Mixing Packets: Pros and Cons of Network Coding”, Proc Wireless Personal Multimedia Communications Symp. – WPMC, Lapland, Finland, September, 2008.


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