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  • xinjin 8:05 pm on April 8, 2012 Permalink | Reply  

    Ensemble Routing 

    My course project will focus ensemble routing. In this post, I’d like to introduce what ensemble routing is. Then I’ll talk about my progress in the future posts.

    As today’s data centers have hundreds of thousands of servers, scalability is a main design goal for data center networks. A major challenge is how to efficiently interconnect servers and provide efficiently traffic management for a huge amount of traffic flows from multiple tenants.

    Ensemble routing provided an efficient way to dynamically manage a huge amount of traffic flows in data center networks. The core idea of ensemble routing is to operate on the granularity of flow ensembles, rather than individual flows. A flow ensemble is a collection of flows, each of which follows the same routing path. Each flow, identified by the tenant ID and packet header tuple, is classified into a traffic class, which determines the QoS treatment for the flow, and a hash class, which is simply calculated by a hash function. The traffic class and the hash class determine the routing class of the flow, i.e., the flow ensemble the flow belongs to. By operating on the flow ensembles, ensemble routing greatly reduces management overhead and is scalable to manage a huge amount of traffic flows. Ensemble routing uses Virtual Local Area Networks (VLANs) to provide routing networks. It needs to effectively assign each flow ensemble, or routing class, to VLANs. The goal is to optimize network utilization for multiple tenants through load balancing.

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    • fotis zygoulis 9:41 am on September 18, 2012 Permalink | Reply

      I would like to thank you for the coursera participation. It is extremely interesting!

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  • xinjin 5:30 pm on April 1, 2012 Permalink | Reply  

    Video Usage in Cellular Networks 

    Video is a dominant factor in mobile traffic today. As smart phones become more and more popular, more people watch videos on their smart phones. However, the investment of ISPs, such as AT&T and Verizon, lags far behind. There is a huge gap between demand and supply in wireless bandwidth in cellular networks today. I did some research on the characteristics of video traffic. I mainly read some reports from ByteMobile (http://www.bytemobile.com/index.html).

    Video traffic characteristics:

    • Video occupies 50% of the traffic.
    • Video users watch 10 videos sequentially, each of which is 60-90 seconds long on average.
    • On an average day, 17% laptop users, 11% iPhone users, 7% Android users, <1% feature phone users consume video content.
    • 10% users generate approximately 90% of total traffic.
    • 40% of total data volume is generated by the top 3% of videos requested.
    • Average video size 5minutes, but only watch about 1 minutes.

     

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    • tomtom android download 3:18 am on November 5, 2012 Permalink | Reply

      Wow, fantastic blog layout! How long have you been blogging for? you made blogging look easy. The overall look of your site is excellent, let alone the content!. Thanks For Your article about Video Usage in Cellular Networks network20q .

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  • xinjin 5:26 pm on March 23, 2012 Permalink | Reply  

    What we can believe in the Internet era 

    http://www.foxnews.com/scitech/2012/03/22/dutch-artist-admits-faking-viral-human-bird-wings-video/

    A video on YouTube recently draws the world’s attention. In the video, a man used his “human bird wings” to fly above a park in the Netherlands! However, it turns out that it was totally a hoax! The filmmaker admitted faking this viral “human bird wings” video.

    The video has been watched more than 4 million times worldwide. In this hoax, they made everything seem to be true. They didn’t just create a series of YouTube videos, but also an official website, a Facebook page, a Twitter feed, and even a LinkedIn profile. Af the first glance, it really seemed that some innovative inventors changed the world. Some people even showed their willingness to buy the product if possible.

    This case raises people’s concern on the truthfulness of information on the Internet. It is not so difficult to make a YouTube video or a Twittter tweet viral on the Internet. People are easily influenced by the viral information. It is really dangerous if some people make use of the Internet to do something really bad. Unlike traditional media, such as newspapers or TVs, the Internet really lacks regulation. People are almost free to post whatever they like to Facebook or Twitter and upload videos to YouTube. We really need a way to limit any damage people can do using the Internet.

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  • xinjin 2:27 am on March 17, 2012 Permalink | Reply  

    51% of Internet traffic is from bots 

    http://www.techspot.com/news/47826-study-51-of-internet-traffic-is-from-bots-31-is-harmful.html

    According to a recently study by Incapsula, 51% of Internet traffic is from bots. It is a little surprising that, at least at the first glance, human beings only generate 49% of the total Internet traffic. Of that 51% bot-related traffic, 20% is from “good” bot traffic such as search engine crawlers, 19% from spies of sorts, 5% from hacking tools, 5% scrapers, and 2% from comment spammers.

    Based on this study, maybe website administrators should rethink their traffic analysis. Not all the traffic they see from their traffic monitoring tools is “good”. A huge amount of the traffic is “bad”, or what they do not want to have. Also, hackers, spies, scrapers, and comment spammers are more than they may have assumed. Maybe they should consider to invest more on security-related software.

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  • xinjin 9:25 pm on March 9, 2012 Permalink | Reply  

    China mobile subscribers hit 1 billion 

    http://www.phonearena.com/news/China-mobile-subscribers-hit-1-billion_id27601

    According to recent news, China mobile subscribers hit 1 billion. This number is really impressive. You can imagine how much profit the carriers, such as China Mobile and China Unicom, are making every year.

    But we should also notice that most subscribers in China still use 2G or 2.5G. 3G subscribers are only about one or two hundred million. There is still a long way to go. On the other hand, China Mobile is going to launch 4G LTE in recent years, and it announces that 4G LTE will be cheaper than 3G. So it seems many people will directly jump to 4G from 2G or 2.5G.

    Also, India seems to have (or already has had) 1 billion mobile subscribers soon. It is really a new era. Even people who cannot afford a PC may have a phone. So they can all access the Internet. It is estimated by Cisco that the mobile traffic will double every year during 2011-2015. The demand increases much faster than the supply of wireless bandwidth. It needs more effort of the ISPs to figure out how to cope with so many subscribers and so much traffic.

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  • xinjin 4:42 am on March 1, 2012 Permalink | Reply  

    Integrating AI into Vehicles 

    http://www.ibtimes.com/articles/305485/20120227/mercedes-benz-apple-siri-drive-kit-plus.htm

    A recent news says that Mercedes Benz plans to use Siri to power its A-class electronics system. With such integration, drivers are able to listen to music, change radio channels, make calls, send texts and find directions using just their voice. And drivers, while driving, can even update their facebook and twitter with Siri. This seems to be a plausible solution, as many things, such as sending texts, are prohibited during driving in most countries. But there are still problems. Firstly, using voice control to update facebook or send texts can still distract drivers, which is undoubtedly very dangerous. Secondly, according my personal experience with Siri, Siri is still not a that good software. It can not precisely understand what users say. For example, when you tell Siri to call Alice, Siri might call someone else. Then considering that in cars there is even more noise than in rooms, the interference may cause Siri to frequently misunderstand users’ request. Users may have to repeat several times until Siri gets what they want. Anyway, I think it is good that artificial intelligence actually begins to influence everyone’s life. I also expect more competitors against Siri to appear.

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  • xinjin 1:47 am on February 26, 2012 Permalink | Reply  

    Women more likely to unfriend than men 

    http://tech.slashdot.org/story/12/02/25/0111219/women-more-likely-to-unfriend-than-men

    A recent study on social networks by the Pew Research Center’s Internet and American Life Projects shows many interesting differences between women’s behaviors on social networks and men’s. One finding indicates that women are more likely to delete friends in their friend list than men. According to the study, 67% of women said that they have deleted friends compared to 58% of men. It seems that women cares more about their privacy and tend to use restrictive privacy settings. I guess there should be some reasons in the different personalities of women and men. Maybe women like to post pictures of the family and update information about their personal life, which makes them care more about who can read these news.

    The study also indicates that “a small group of what might be described as trigger-happy users say they post updates, comments, photos, or videos that they later regret sharing.” This is also an interesting phenomenon. Social networks make sharing more easily than ever before, which may have a potential effect on people’s willingness to share. It would be interesting if we could model such effect and see what factors contribute to such effect. I think the number of friends a person have may contribute a lot to her/his willingness to share. Intuitively, if one has lots of friends, after she/he does something exciting, she/he may want her/his friends to know it quickly.

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  • xinjin 12:51 am on February 19, 2012 Permalink | Reply  

    The age of big data 

    http://www.nytimes.com/2012/02/12/sunday-review/big-datas-impact-in-the-world.html?pagewanted=all

    Recently, the above article about “big data” in NYTimes raises heated discussions. Definitely we are in the era of “big data”. Sensors all around the world are collecting tons of data every second. Even our smart phones contain a bunch of small sensors, which records our everyday life. Storage companies, such as EMC, are in the best of their time.

    However, one of the biggest questions is what we can do with so much data. It seems that people were drowned in such a big amount of data. As the stories in the article shows, people are still lack of the ability to discover useful information from large-scale data. While people are continuously spending money on collecting more and more data, such investment does not seem to have enough reward now. This is where needs more development in computer science, not only theoretical results in data mining and machine learning, but also real systems that can be put into practical use.

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  • xinjin 4:04 pm on February 12, 2012 Permalink | Reply  

    IBM seeks patent on judging programmers by commits 

    http://yro.slashdot.org/story/12/02/09/1624232/ibm-seeks-patent-on-judging-programmers-by-commit

    IBM applies for a patent which is used to judge programmers by commits. It can automatically analyze a programmer’s profile with data related to code repository updates by the programmer. With such analysis, it says it can help managers “avoid wasted time with ineffective developers”. I just wonder that by analyzing the algorithm the patent uses carefully, whether an inefficient programmer could pretend to be an efficient programmer.

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