Comcast Opens Curtains On How They Filter Your Traffic

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Comcast has just released a series of documents in response to the Federal Communications Commission detailing how, exactly, the ISP filters your traffic. Based on their traffic analysis, five protocols (Ares, BitTorrent, eDonkey, FastTrack and Gnutella) were especially filtered. Not anymore. Now Comcast is going to be throttling ALL traffic you generate, even if it's from their own Fancast streaming video service, if you're generating abnormally high traffic compared to your peers. On the bright side, it's good that your torrents aren't getting slowed down, but on the other hand, "legal" applications like Netflix or Amazon will be affected as well. This probably won't be a big deal to all that many of you, as Comcast says the throttling only occurs during periods of congestion, and in total will only impact 1% of users. (It's likely that many Giz readers are in that 1% of bandwidth hogs though.) In any case, you'll still have to watch out that you don't run over the 250GB monthly cap, or else your net will become disconnected entirely. FAQ below:

Why does Comcast manage its network? Comcast manages its network with one goal: to deliver the best possible broadband Internet experience to all of its customers. High-speed bandwidth and network resources are not unlimited. Managing the network is essential to promote the use and enjoyment of the Internet by all of our customers. We use reasonable network management practices that are consistent with industry standards. We also try to use tools and technologies that are minimally intrusive. Just as the Internet continues to change and evolve, so too, will our network management practices to address the challenges and threats on the Internet. All Internet service providers need to manage their networks and Comcast is no different. In fact, many of them use the same or similar tools that Comcast does. If we didn't manage our network, our customers would be subject to the negative effects of spam, viruses, security attacks, network congestion, and other risks and degradations of the service. By engaging in reasonable and responsible network management, Comcast can deliver the best possible broadband Internet experience to all of its customers. How does Comcast manage its network? Comcast uses various tools and techniques to manage its network, deliver the Service, and ensure compliance with the Acceptable Use Policy and the Comcast Agreement for Residential Services available at These tools and techniques are dynamic, like the network and its usage, and can and do change frequently. For example, these network management activities may include identifying spam and preventing its delivery to customer e-mail accounts, detecting malicious Internet traffic and preventing the distribution of viruses or other harmful code or content and using other tools and techniques that Comcast may be required to implement in order to meet its goal of delivering the best possible broadband Internet experience to all of its customers. Does network management change over time? Yes. The Internet is highly dynamic. As the Internet and related technologies continue to evolve and advance, Comcast's network management tools will evolve and keep pace so that we can deliver an excellent, reliable, and safe online experience to all of our customers. In March 2008, Comcast announced that it will migrate to a new network congestion management technique before the end of the year. (See more FAQs about that in this section.) How will the new technique work? The new network congestion management practice works as follows: If a certain area of the network nears a state of congestion, the technique will ensure that all customers have a fair share of access to the network. It will identify which customer accounts are using the greatest amounts of bandwidth and their Internet traffic will be temporarily managed until the period of congestion passes. Customers will still be able to do anything they want to online, and many activities will be unaffected, but they could experience things like: longer times to download or upload files, surfing the Web may seem somewhat slower, or playing games online may seem somewhat sluggish. The new technique does not manage congestion based on the online activities, protocols or applications a customer uses, rather it only focuses on the heaviest users in real time, so the periods of congestion could be very fleeting and sporadic. It is important to note that the effect of this technique is temporary and it has nothing to do with aggregate monthly data usage. Rather, it is dynamic and based on prevailing network conditions as well as very recent data usage. Will the technique target P2P or other applications, or make decisions about the content of my traffic? No. The new technique is "protocol-agnostic," which means that the system does not manage congestion based on the applications being used by customers. It is content neutral, so it does not depend on the type of content that is generating traffic congestion. Said another way, customer traffic is congestion-managed not based on their applications, but based on current network conditions and recent bytes transferred by users. How does the new network management technique impact me and my use of the Comcast High Speed Internet service? With this new technique, most customers will notice no change in their Internet experience. The goal of congestion management is to enable all users to have access to a fair share of the network at peak times, when congestion occasionally occurs. Congestion management focuses on the consumption activity of individual customer accounts that are using a disproportionate amount of bandwidth. As a result, and based on our technical trials of this technique, we expect that the large majority of customers will not be affected by it. In fact, based on consumer data collected from these trials, we found that on average less than 1% of our high-speed Internet customers are affected by the approach. How often does Comcast expect to use this technique? Based on market trials to date, Comcast expects that select portions of the network will be in a congested state only for relatively small portions of the day, if at all. During these trials, Comcast did not receive a single customer complaint that could be traced to this new congestion management practice, despite having publicized the trials and notifying customers involved in the trials via e-mail. Comcast will continue to monitor how user traffic is affected by these new congestion management techniques and will make the adjustments reasonably necessary to ensure that our Comcast High-Speed Internet customers have a high-quality online experience. Can you give me some "real world" examples of how much bandwidth consumption would be considered too much? For example, how many movies would I have to download to be affected by this new technique? Since the technique is dynamic and works in real time, the answer really depends on a number of factors including overall usage, time of day and the number of applications a customer might be running at the same time. First, the local network must be approaching a congested state for our new technique to even look for traffic to manage. Assuming that is the case, customers' accounts must exceed a certain percentage of their upstream or downstream (both currently set at 70%) bandwidth for longer than a certain period of time, currently set at fifteen minutes. A significant amount of normal Internet usage by our customers does not last that long. For example, most downloads would have completed within that time, and the majority of streaming and downloading will not exceed the threshold to be eligible for congestion management. And the majority of longer-running applications, such as VoIP, video conferencing, and streaming video content (including HD streaming on most sites) will not exceed these thresholds either. The point of the technique is to deliver the best overall online experience possible. The technique should help ensure that all customers get their fair share of bandwidth resources to enjoy all that the Internet has to offer and that includes surfing the web, reading emails, downloading movies, watching streaming video, gaming or listening to music. How will customers know they are being managed? We are exploring ways to create new tools that will let customers know when the management is occurring. In the short term, our efforts are focused on transitioning to the new technique as soon as possible. We believe this sort of congestion notification should be an Internet standard and have been discussing this issue in technical bodies like the Internet Engineering Task Force. We believe the use of Internet Standards for such a real-time notification is important as applications developers can write for networks beyond the Comcast network. However we are planning to develop a capability that may enable a customer to see if they were managed in the past, though this is not yet ready for testing. Does this technique apply to both Commercial and Residential services? Yes. How is this announcement related to the recent 250 GB monthly usage threshold? The two are completely separate and distinct. The new congestion management technique is based on real-time Internet activity. The goal is to avoid congestion on our network that is being caused by the heaviest users. The technique is different from the recent announcement that 250 GB/month is the aggregate monthly usage threshold that defines excessive use. Is Comcast Digital Voice affected by this technique? What about other VoIP providers? Comcast Digital Voice is a separate facilities-based IP phone service that is not affected by this technique. Comcast customers who use VoIP providers that rely on delivering calls over the public Internet who are also using a disproportionate amount of bandwidth during a period when this network management technique goes into effect may experience a degradation of their call quality at times of network congestion. It is important to note, however, that VoIP calling in and of itself does not use a significant amount of bandwidth. Furthermore, our real-world testing of this technique did not indicate any significant change in the quality of VoIP calls, even for managed customer traffic during periods of congestion. What about and streaming video or video downloads? What will happen to them? During periods of congestion, any customers who are using a disproportionate amount of bandwidth – no matter what type or content of the online activity (for example, it does not matter if the content is coming from a Comcast owned site like or not) – may be affected by this technique. Our technique also has no ability to determine the applications or protocols being used or the content, source or destination. Does Comcast block peer-to-peer ("P2P") traffic or applications like BitTorrent, Gnutella, or others? No. Today, Comcast does not block P2P traffic or applications like BitTorrent, Gnutella, or others as part of its current network congestion management technique. It is important to note, however, that the current network congestion technique, which will be replaced by the end of 2008, may on a limited basis temporarily delay certain P2P traffic when that traffic has, or is projected to have, an adverse effect on other customers' use of the service. We do this because, in certain situations, that type of traffic consumes a disproportionately large amount of network resources. Does Comcast discriminate against particular types of online content? No. Comcast provides its customers with full access to all the content, services, and applications that the Internet has to offer. However, we are committed to protecting customers from spam, phishing, and other unwanted or harmful online content and activities. Comcast uses industry standard tools and generally accepted best practices and policies to help it meet this customer commitment. In cases where these tools and policies identify certain online content as harmful and unwanted, such as spam or phishing Web sites, this content is usually prevented from reaching customers. In other cases, these tools and policies may permit customers to identify certain content that is not clearly harmful or unwanted, such as bulk e-mails or Web sites with questionable security ratings, and enable those customers to inspect the content further if they want to do so.