Comcast “Traffic Shaping”?

by on October 22, 2007 · 14 comments

As Jerry wrote up briefly over the weekend, Comcast is alleged to have been “shaping” traffic over its network. Proponents of broadband regulation have already gotten a bit conclusory, even triumphal, expecting that this makes the case for public utility regulation of broadband service.

But I expect that we’ll soon learn more about the situation, and the conclusions to be drawn from it will be less obvious. There might be legitimate security reasons for what Comcast has done. We’ll see. We should expect full disclosure from Comcast.

My take: If Comcast is “shaping” traffic inconsistent with their terms of service, for non-network-security reasons such as copyright protection or surreptitious usage control, they shouldn’t be doing that.

More important is the meta-point: Independent testers found what they believe to be an impropriety in Comcast’s provision of broadband. They called it out, and interested parties among advocacy organizations and the media swarmed all over it. Comcast has to answer the charge, whether meritorious or not.

These are market processes working their will, and the outcome will be reached in short order – whether Comcast backs away from an improper practice, whether we learn that Comcast was not acting badly, or whether Comcast amends its terms to reflect what it thinks serves customers best.

This doesn’t conclude the discussion of whether there should be regulation. It allows us to refine the discussion: The proponents of regulation should now be challenged to write the regulation that would suss out this kind of (still alleged) misbehavior, distinguish it from appropriate network management, and ban it – without wrapping provision of Internet service in red tape or creating regulatory capture that suppresses competition. Good luck with that!

Obviously, more to come.

  • http://www.manifestdensity.net Tom

    This doesn’t conclude the discussion of whether there should be regulation. It allows us to refine the discussion: The proponents of regulation should now be challenged to write the regulation that would suss out this kind of (still alleged) misbehavior, distinguish it from appropriate network management, and ban it – without wrapping provision of Internet service in red tape or creating regulatory capture that suppresses competition. Good luck with that!

    I agree that it’s a tricky problem, but it doesn’t seem appropriate to simply deem it intractable. Requiring Comcast to disclose the limits and measures they’re imposing would be a great first step. Prohibiting them from impersonating third parties with whom their users are trying to communicate — as they are doing when they send these RST packets — would be another useful measure. These two things are the bare minimum that any solution should include.

    From there it might be appropriate to mandate some more transparent pricing — require that Comcast offer a metered option, perhaps, similar to how they’ve been required to offer a broadcast-only package. No one’s arguing for price controls or for congress to get into the sysadmin business. But right now Comcast is stifling innovation by seeking rent on bandwidth-sipping users who’re content to use the web and email their grandkids. There needs to be a way for new technologies to flourish, too.

    Ideally the FTC would simply require Comcast to fully disclose what they’re up to, then allow the market to decide what the result will be. In practice I doubt there’s enough competition for that to work very well. We should at least think about what we can do to improve the situation.

  • http://bennett.com/blog Richard Bennett

    The solution that Comcast employs to ration BT uploads does not invove any form of identity theft, it simply stifles BT seeds that exceed some threshold. Given the limitations of the DOCSIS 1.1 technology in their network, it’s entirely reasonable. See: “The Interaction Between the DOCSIS 1.1/2.0 MAC Protocol and TCP Application Performance”:

    “We have developed a model of the Data over Cable (DOCSIS) 1.1/2.0 MAC and physical layers using
    the ‘ns’ simulation package [2]. In previous work, we reported on the impact of several DOCSIS
    operating parameters on TCP/IP performance [3]. In this paper we extend those results by looking in
    greater detail at the impact that the MAC layer has on TCP performance when using the DOCSIS best
    effort service. We show that the interaction between DOCSIS and TCP exposes a denial of service
    vulnerability. By taking advantage of the inefficiency surrounding upstream transmissions, a hacker can severely impact network performance.”

    In effect, several BT streams in the DOCSIS return path mimics a DoS attack to non-BT users. That’s not cool and it’s right for Comcast to prevent it.

  • http://www.cato.org/people/harper.html Jim Harper

    Thanks for the thoughtful comment, Tom. The problem of regulating here isn’t intractable, though it is very difficult.

    My meta-point remains: Independent testing revealed alleged wrongful behavior by Comcast and an array of forces are requiring them to account for it. This is being done through operation of the market, without government intervention. The “Comcast kerfuffle” will be resolved – one way or another – before federal agencies can even get their computers booted up.

    I appreciate the light-touch suggestions you make for mandated disclosure. Disclosure is good, but testing is the ultimate disclosure, and it’s an inherent power of anyone using the service. We’re already seeing that the Fourth Estate can test on our behalf to good effect.

    (Richard, I’m gonna study this. It’s beyond my current technical competence.)

  • http://www.manifestdensity.net Tom

    This doesn’t conclude the discussion of whether there should be regulation. It allows us to refine the discussion: The proponents of regulation should now be challenged to write the regulation that would suss out this kind of (still alleged) misbehavior, distinguish it from appropriate network management, and ban it – without wrapping provision of Internet service in red tape or creating regulatory capture that suppresses competition. Good luck with that!

    I agree that it’s a tricky problem, but it doesn’t seem appropriate to simply deem it intractable. Requiring Comcast to disclose the limits and measures they’re imposing would be a great first step. Prohibiting them from impersonating third parties with whom their users are trying to communicate — as they are doing when they send these RST packets — would be another useful measure. These two things are the bare minimum that any solution should include.

    From there it might be appropriate to mandate some more transparent pricing — require that Comcast offer a metered option, perhaps, similar to how they’ve been required to offer a broadcast-only package. No one’s arguing for price controls or for congress to get into the sysadmin business. But right now Comcast is stifling innovation by seeking rent on bandwidth-sipping users who’re content to use the web and email their grandkids. There needs to be a way for new technologies to flourish, too.

    Ideally the FTC would simply require Comcast to fully disclose what they’re up to, then allow the market to decide what the result will be. In practice I doubt there’s enough competition for that to work very well. We should at least think about what we can do to improve the situation.

  • http://bennett.com/blog Richard Bennett

    The solution that Comcast employs to ration BT uploads does not invove any form of identity theft, it simply stifles BT seeds that exceed some threshold. Given the limitations of the DOCSIS 1.1 technology in their network, it’s entirely reasonable. See: “The Interaction Between the DOCSIS 1.1/2.0 MAC Protocol and TCP Application Performance”:

    “We have developed a model of the Data over Cable (DOCSIS) 1.1/2.0 MAC and physical layers using
    the ‘ns’ simulation package [2]. In previous work, we reported on the impact of several DOCSIS
    operating parameters on TCP/IP performance [3]. In this paper we extend those results by looking in
    greater detail at the impact that the MAC layer has on TCP performance when using the DOCSIS best
    effort service. We show that the interaction between DOCSIS and TCP exposes a denial of service
    vulnerability. By taking advantage of the inefficiency surrounding upstream transmissions, a hacker can severely impact network performance.”

    In effect, several BT streams in the DOCSIS return path mimics a DoS attack to non-BT users. That’s not cool and it’s right for Comcast to prevent it.

  • http://www.cato.org/people/harper.html Jim Harper

    Thanks for the thoughtful comment, Tom. The problem of regulating here isn’t intractable, though it is very difficult.

    My meta-point remains: Independent testing revealed alleged wrongful behavior by Comcast and an array of forces are requiring them to account for it. This is being done through operation of the market, without government intervention. The “Comcast kerfuffle” will be resolved – one way or another – before federal agencies can even get their computers booted up.

    I appreciate the light-touch suggestions you make for mandated disclosure. Disclosure is good, but testing is the ultimate disclosure, and it’s an inherent power of anyone using the service. We’re already seeing that the Fourth Estate can test on our behalf to good effect.

    (Richard, I’m gonna study this. It’s beyond my current technical competence.)

  • http://bennett.com/blog Richard Bennett

    It’s actually pretty simple. The cable modem network was designed around the assumptions that most traffic is downstream and bursty, and BT in seeding mode is upstream and sustained. There aren’t any nicer ways of making the traffic conform to these design assumptions at the moment than the ones that Comcast uses.

    In the future, the cable modem network will use a new standard, DOCSIS 3.0, that will make it more symmetrical, but that’s a long way and lot of dollars to deploy.

    To simplify down to the bare essentials, BitTorrent in seeding mode (“seeding” is the only thing affected, you can “download” to your heart’s content) is a server, and servers are banned on Comcast’s network.

  • http://bennett.com/blog Richard Bennett

    It’s actually pretty simple. The cable modem network was designed around the assumptions that most traffic is downstream and bursty, and BT in seeding mode is upstream and sustained. There aren’t any nicer ways of making the traffic conform to these design assumptions at the moment than the ones that Comcast uses.

    In the future, the cable modem network will use a new standard, DOCSIS 3.0, that will make it more symmetrical, but that’s a long way and lot of dollars to deploy.

    To simplify down to the bare essentials, BitTorrent in seeding mode (“seeding” is the only thing affected, you can “download” to your heart’s content) is a server, and servers are banned on Comcast’s network.

  • http://enigmafoundry.wordpress.com/ enigma_foundry

    These are market processes working their will, and the outcome will be reached in short order – whether Comcast backs away from an improper practice, whether we learn that Comcast was not acting badly, or whether Comcast amends its terms to reflect what it thinks serves customers best.

    By this very low standard, it is impossible for there ever to be anything disclosed that is an example of a market failure and would require government intervention because if it is discovered and therefore discussed, you would just say something like: “My meta-point remains: Independent testing revealed alleged wrongful behavior by Comcast and an array of forces are requiring them to account for it. This is being done through operation of the market, without government intervention.”

    However, realize that this is just yet another example of a large corporation stifling public discussion to further its business plan. The internet is the new town square, and to permit toll booths and road blocks and secret protocols to intervene is unacceptable. Comcast has, despite the gnashing of teeth of the libertarians, convincingly made the argument for network neutrality legislation that now one else had as yet made so eloquently.

    The secret throttling of bandwidth is restraint of freedom of speech; many use BT to disseminate political speech that would otherwise be less accessible, and it cannot be ignored that the distribution of linux and FOSS to dismantle the centralized power structures of large corporations is itself an act with a political dimension. So, any attempt to dismantle or disrupt BT traffic is an act political repression.

  • http://enigmafoundry.wordpress.com eee_eff

    These are market processes working their will, and the outcome will be reached in short order – whether Comcast backs away from an improper practice, whether we learn that Comcast was not acting badly, or whether Comcast amends its terms to reflect what it thinks serves customers best.

    By this very low standard, it is impossible for there ever to be anything disclosed that is an example of a market failure and would require government intervention because if it is discovered and therefore discussed, you would just say something like: “My meta-point remains: Independent testing revealed alleged wrongful behavior by Comcast and an array of forces are requiring them to account for it. This is being done through operation of the market, without government intervention.”

    However, realize that this is just yet another example of a large corporation stifling public discussion to further its business plan. The internet is the new town square, and to permit toll booths and road blocks and secret protocols to intervene is unacceptable. Comcast has, despite the gnashing of teeth of the libertarians, convincingly made the argument for network neutrality legislation that now one else had as yet made so eloquently.

    The secret throttling of bandwidth is restraint of freedom of speech; many use BT to disseminate political speech that would otherwise be less accessible, and it cannot be ignored that the distribution of linux and FOSS to dismantle the centralized power structures of large corporations is itself an act with a political dimension. So, any attempt to dismantle or disrupt BT traffic is an act political repression.

  • http://www.cato.org/people/harper.html Jim Harper

    Thanks, Richard.

  • http://www.cato.org/people/harper.html Jim Harper

    Thanks, Richard.

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