Frequently Asked Questions about Network Management

Based on our recent announcement we will be revising this page soon.

 

Comcast is committed to providing the best online experience possible for all of its customers. The company uses reasonable network management practices that are consistent with industry standards. Comcast maintains an Acceptable Use Policy ("AUP") located at http://www.comcast.com/Corporate/Customers/Policies/HighSpeedInternetAUP.html for its XFINITY Internet Service customers. Comcast also maintains an AUP for the XFINITY Internet2Go service at http://www.comcast.com/Corporate/Customers/Policies/Internet2goAUP.html. The AUPs and these FAQs discuss Comcast's (and its providers’) network management techniques and approaches.

The following Frequently Asked Questions are intended to help clarify what Comcast means by network management.

Why does Comcast manage its network?

How does Comcast manage its network?

Does network management change over time?

How does the current congestion management technique work?

Does the congestion management technique target peer-to-peer ("P2P") or other applications, or make decisions about the content of my traffic?

How does the congestion management technique impact me and my use of the XFINITY Internet service?

How often does Comcast expect to use this congestion management technique?

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 congestion management technique?

How will customers know they are being managed?

Does this congestion management technique apply to both Commercial and Residential services?

Does this congestion management technique apply to XFINITY Wi-Fi service?

Is XFINITY Voice or Comcast Digital Voice affected by this congestion management technique? What about other VoIP providers?

What about XFINITY TV and XfinityTV.com and streaming video or video downloads? What will happen to them?

Does Comcast block P2P traffic or applications like BitTorrent, Gnutella, or others?

Does Comcast discriminate against particular types of online content?

Does this congestion management technique apply to XFINITY Internet2Go service?

What congestion management technique applies to XFINITY Internet2Go service?

Does Comcast employ network security practices in addition to the congestion management technique?

Does Comcast have rules regarding the attachment of devices to its network by customers?

How can I contact Comcast if I have any questions about network management?

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 its service, and ensure compliance with the Acceptable Use Policy and the Customer Agreement for Residential Services available at http://www.comcast.com/Corporate/Customers/Policies/SubscriberAgreement.html. 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 email 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. We will provide updates here and in other appropriate locations if we make important or significant changes to our network management techniques.

How does the current congestion management technique work?

The current congestion management technique 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 technique does not manage congestion based on the online activities, protocols or applications a customer uses; it only focuses on the heaviest users in real time, so the periods of congestion typically tend to 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 a customer’s aggregate monthly data usage. Rather, it is dynamic and based on prevailing network conditions as well as a customer’s data usage over a very recent period of time.

Our congestion management system was disclosed in detail in 2008 to the Federal Communications Commission in http://downloads.comcast.net/docs/Attachment_B_Future_Practices.pdf and this filing has since been disclosed in an Internet Engineering Task Force (IETF) document in RFC 6057.

Does the congestion management technique target peer-to-peer ("P2P") or other applications, or make decisions about the content of my traffic?

No. The technique is "protocol-agnostic," which means that the system does not manage congestion based on the applications being used by customers. It is also 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 the applications or content being used, but based on current network conditions and recent amounts of data transferred by users.

How does the congestion management technique impact me and my use of the XFINITY Internet service?

With this 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 experience with this technique, we have determined that the large majority of customers are not be affected by it. In fact, based on our experience, we find that on average less than one percent of our High-Speed Internet customers are affected by the approach. Our experience also shows that when our systems apply the congestion management technique to an individual user’s account, it is usually only in effect for a very brief period of time.

How often does Comcast expect to use this congestion management technique?

Based on our experience using this system, Comcast has determined that select portions of the network tend to be in a congested state only for relatively small portions of the day, if at all.

Comcast monitors how user traffic is affected by this system and will make the adjustments reasonably necessary to ensure that our XFINITY Internet customers have a high-quality online experience. Comcast also routinely evaluates its overall network performance and periodically enhances its network by adding capacity to address congestion and other performance issues.

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 congestion management 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 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 15 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 email, downloading movies, watching streaming video, gaming or listening to music.

How will customers know they are being managed?

We believe congestion notification should be an Internet standard and have been discussing this issue in technical bodies like the IETF. The Congestion Exposure (CONEX) working group at the IETF is currently considering this issue.

Does this congestion management technique apply to both Commercial and Residential services?

Yes.

Does this congestion management technique apply to XFINITY Wi-Fi service?

Yes.

Is XFINITY Voice or Comcast Digital Voice affected by this congestion management technique? What about other VoIP providers?

XFINITY Voice or Comcast Digital Voice are a separate facilities-based IP phone service that is not affected by this technique. This phone service also does not affect the last mile capacity for, or the performance of, the XFINITY Internet service.

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 congestion 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 experience with this technique does not indicate any significant change in the quality of VoIP calls, even for managed customer traffic during periods of congestion.

What about XFINITY TV and XfinityTV.com 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 XFINITY TV and XfinityTV.com 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 P2P traffic or applications like BitTorrent, Gnutella, or others?

No. Comcast does not block P2P traffic or applications like BitTorrent, Gnutella, or others as part of its current network congestion management technique.

Does Comcast discriminate against particular types of online content?

No. Comcast provides its customers with full access to all the lawful 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 email or Web sites with questionable security ratings, and enable those customers to inspect the content further if they want to do so. You can learn more about Comcast’s anti-spam and pro-network security efforts at http://customer.comcast.com/Pages/FAQViewer.aspx?Guid=d7e7f15b-8e1b-4035-bb8e-9b934df33829.

Does this congestion management technique apply to XFINITY Internet2Go service?

No. The mobile Internet networks that the XFINITY Internet2Go service uses are operated by third parties that Comcast works with to provide access to the service. These third parties manage their mobile Internet networks using their own techniques, but they do so with one goal: to deliver the best possible mobile Internet experience to all customers.

What congestion management technique applies to XFINITY Internet2Go service?

In general, Comcast’s mobile Internet network suppliers manage their networks to avoid network congestion based on actual customer usage of individual segments or sectors of the network in order to provide all users with sufficient bandwidth. The suppliers primarily manage their mobile Internet networks by temporarily limiting speeds or the amount of data that can be transferred until the conditions that create network congestion have passed. Comcast’s mobile Internet network suppliers do not manage their mobile Internet network using protocol- or application-based methods.

In addition to limiting data transfer speeds and the amount of data transferred to alleviate network congestion, our mobile Internet network suppliers may also use the following congestion management techniques:

 

  • On the 3G network (a third generation network that follows the CDMA (Code Division Multiple Access) standard), the supplier may use a proportional fairness scheduler algorithm that allocates network resources based on radio frequency signal quality and other metrics. During times of congestion, the proportional fairness scheduler algorithm ensures no one user is deprived of network resources.
  • On the 4G network (a fourth generation network that follows the WiMAX (Worldwide Interoperability for Microwave Access) standard), the supplier may periodically measure a user’s bandwidth usage on a specific network segment or sector, as well as measure the overall bandwidth usage for all users on that segment or sector. In situations where a user is consuming high amounts of bandwidth and the bandwidth being used on that network segment or sector is being used at high levels, the supplier may temporarily adjust the network resources made available to that user until the conditions for network congestion have passed.

 

Does Comcast employ network security practices in addition to the congestion management technique?

Yes. As described above, Comcast employs a number of practices to help prevent unwanted communications such as spam as well as protect the security of our customers and network. Comcast limits the number of login, SMTP, DNS, and DHCP transactions per second (at levels far above ‘normal’ rates) that customers can send to Comcast’s servers in order to protect them against Denial of Service (DoS) attacks. We do not disclose the exact rate limits in order to maintain the effectiveness of these measures, which ensure that these critical services are available for all of our customers. Relevant limitations regarding Comcast’s email servers can be found at http://customer.comcast.com/Pages/FAQViewer.aspx?Guid=2fcfc017-8dc5-4464-945c-fe5ec58d9d4d. In order to further protect our customers, Comcast blocks a limited number of ports that are commonly used to send spam, launch malicious attacks, or steal a customer’s information, for example. You can see a list of these ports and additional details at http://customer.comcast.com/Pages/FAQViewer.aspx?Guid=d3609bda-26c4-4200-a9ba-ba991251a9f6. In addition, Comcast conducts several security initiatives, and offers security tools for our customers at http://security.comcast.net/.

Does Comcast have rules regarding the attachment of devices to its network by customers?

You can find information concerning the devices approved for use on the network, and the tiers of our service that they are appropriate for, at http://mydeviceinfo.comcast.net/. In order for a cable modem device to be approved for use on the network, it must pass CableLabs certification, UL certification, FCC certification, and Comcast device testing covering things like DOCSIS performance and integration with Comcast’s network and systems.

How can I contact Comcast if I have any questions about network management?

Go to the page at https://www.comcast.com/Corporate/Customers/contactus/ContactUs.html for more information about contacting Comcast Customer Service.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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