Comcast Outlines New Broadband Policy

Slatterz writes "US cable provider Comcast has presented its long-term solution for managing broadband traffic. The new system is set at putting to bed a minor scandal that erupted around the company when it was found that Comcast deliberately limited traffic for certain applications. The company said that under its new system, traffic will be analyzed every fifteen minutes. Users who are found to be occupying large amounts of bandwidth will be placed at a lower priority for network access behind users with less bandwidth-intensive traffic. The new system will not replace or be related to the company's earlier installment of bandwidth caps, which limited a user's data intake to 250GB per month."

Dang...

There are only two games in town: ATT's DSL (slow) and Comcast (Fast, but with strings).

What's the point of having the internet when you can't do anything on it?

Re:Dang...

I don't know what you're talking about. Where I live, I have two options.

1. ATT's DSL: Full rated 6Mbps speed
2. Comcast: No matter what speed grade, almost never faster than 6Mbps, yet more expensive.

Beats my old options: Comcast, unreliable ISDN, or 12.6Kbps dial-up.

My take on this? It's a much better policy than just randomly killing connections that look like they might be doing something that may be using large amounts of bandwidth.

Re:Dang...

right up until your skype or vonage sessions are interperted as too much bandwidth. Also video chat is the kind of thing that will probably set this off.

lots of high bandwidth low latency connections are required by many programs to provide features that dial up couldn't.

Re:Dang...

The solution then is to rate-limit at the router or TCP stack, or for applications to start being more careful about how much bandwidth they use -- just because a user has 6.0Mbps available for peak speed, doesn't mean that applications should assume that they can or should use as much of it as possible, all the time.

P2P applications have had rate-limiting controls for a long time; it's probably about time for Skype and video-chat applications to have them too. Skype is particularly bad in this regard because it automatically defaults to the highest-quality codec that a connection supports. While this might make sense on fixed-bandwidth connections, it's not great for the majority of broadband connections, which have the capability of pushing a high peak speed, but shouldn't be expected to sustain that peak for very long. (And this isn't a bad thing or rare, either; lots of "real" internet connections are the same way. You can buy a 100Mb pipe because you occasionally need the full 100 megabits, even though you can't afford to saturate it 24/7. I'd wager most SLAed connections at .coms and .edus are like this.)

In general, it's a pretty fair policy, especially because it only goes into effect when a neighborhood node starts to become congested. (Unlike their 250GB/mo cap and their old policy, which didn't care whether you were actually competing for resources with anyone else.) If I'm using huge amounts of bandwidth for Skype or video-chat, to the point where my neighbors are being affected even though they're just trying to check their mail and log off, they're not going to care what application I'm using. It's fundamentally no different, to anyone else in my neighborhood, if I'm taking up all the bandwidth on the upstream node with VoIP calls, Linux ISOs, or midget porn. They all have the same effect on my network neighbors, and all should get me throttled.

What needs to happen, is applications need to get smarter about their bandwidth consumption. If a VoIP program finds itself getting throttled (increased latency), it should try dialing down its bandwidth usage -- by choosing a tighter codec, perhaps -- and seeing if the situation improves.

Re:What...?

So suddenly any large use of BW is illegal? Way to distract from the point.

Re:What...?

I'm not sure why this was modded -1, Flamebait. The parent makes a good point - as I posted in a semi-related thread a couple of days ago, I rented a movie from the Playstation store as an HD rental. The filesize was 6275 MB (around 6 GB). This download definitely saturated my connection, as I had the whole thing in around 2 hours. I realize that Comcast has a way of telling (or maybe they don't, who knows) P2P traffic from a straight download, but ultimately the question is the same - if I'm blasting a 6 GB file download in an hour or two, does that piss them off? Because I'm going to be mad if it does, since it was a perfectly legitimate use of the service that I'm paying for (vs. some "gray area" activities).

Re:What...?

Offsite backups.

My disk array syncs to a disk array about 2000 miles away, and that one syncs to mine.

I used about 230G last month, and that was the largest part.

The next largest component was torrents of lectures (such as this [stanford.edu] machine learning class offered by Stanford).

Re:What...?

You could always upgrade to a class of service that doesn't have the caps, or has caps in line with what you require.

A system in which people like you who use 100s or thousands of gigabytes per month pay more than people who use 10 or 15 a year seems entirely fair to me.

Re:What...?

Then shouldn't the people who use 10 or 15 a year pay considerably less than they are now?

After all, the only reason pricing is at this point is because they reasoned that the people using the service at only 5% capacity would effectively subsidized the others who use it at 100% capacity.

If you're now making those who would use it at 100% capacity pay more for service, shouldn't those who are only using a fraction of the network capacity get a major discount to their connectivity?

Re:What...?

Uh, let's see:

  - Downloading F/OSS software?
  - hulu.com?
  - Various TV networks?
  - Netflix?
  - VOIP?

Face it: (IMHO) Comcast is afraid of streaming video sites, and are using P2P as an excuse to curb competition. They do not want to happen to them what happened to land line telephone companies when cellular and VOIP took off.

Re:Dang...

So are the people using IPTV screwed? They will be queued worse due to their high bandwidth usage again and again if they watch a long IPTV show. What about households with multiple Youtube users streaming and watching different videos at the same time? Both are completely legal, but seems to something that occupies high bandwidth.

Re:Dang...

Here's an email from one of Comcast's engineers recently sent to Dave Farber's Interesting People mailing list. It clarifies the policy quite well:

From: "Livingood, Jason"
Subject: Clarifying Misconceptions of the New Comcast Congestion Mgmt Syste

Hi Dave

I wanted to try to clear up a misconception about how the new Comcast congestion management system works. I believe we have both heard people complain that they fear that they will be unable to use their provisioned speeds during off-peak hours, for example, or at all times of the day, or that users are somehow throttled to a set speed. Neither of these two things are correct. Part of the problem appears to be confusion over how a user's traffic enters a lower priority QoS state, so I hope to clarify that here

In order for any traffic to be placed in a lower priority state, there must first be relatively high utilization on a given CMTS port. A CMTS port is an upstream or downstream link, or interface, on the CMTS in our network. The CMTS is basically an access network router, with HFC interfaces on the subscriber side, and GigE interfaces on the WAN/Internet side. Today, on average, about 275 cable modems share the same downstream port, and about 100 cable modems share the same upstream port (see page 5 of Attachment B of our Future Practices filing with the FCC, available at http://downloads.comcast.net/docs/Attachment_B_Future_Practices.pdf [comcast.net]). We define a utilization threshold for downstream and upstream separately. For downstream traffic, a port must average over 80% utilization for 15 minutes or more. For upstream traffic, a port must average over 70% utilization for 15 minutes or more

When one of these threshold conditions has been met, we consider that individual port (not all ports on the CMTS) to be in a so-called Near Congestion State. This simply means that the pattern of usage is predictive of that network port approaching a point of high utilization, where congestion could soon occur. Then, and only then, do we search the most recent 15 minutes of user traffic on that specific port, in order to determine if a user has consumed more that 70% of their provisioned speed for greater than 15 minutes. By provisioned speed, we mean the "up to" or "burst to" speed of their service tier. This is typically something like (1) 8Mbps downstream / 2Mbps upstream or (2) 6Mbps downstream / 1Mbps upstream

So how does this work in action? Let's say that a downstream port has been at 85% utilization for more than 15 minutes. That specific downstream port is identified as being in a Near Congestion State since it exceeded an average of 80% over that time. We then look at the downstream usage of the ~275 cable modems using that downstream port. That port has a mix of users that have been provisioned either 8Mbps or 6Mbps, so 70% of their provisioned speed would be either 5.6Mbps or 4.2Mbps, respectively. So let's use the example of a user with 8Mbps/2Mbps service on this port. In order for their traffic to be marked with a lower priority on this downstream port, they must be consuming 5.6Mbps in the downstream direction for 15 minutes or more, while said port is highly utilized

Once that condition has been met, that user's downstream traffic is now tagged with the lower priority QoS level. This will have *no* effect whatsoever on the traffic of that user, until such time as an actual congestion moment subsequently occurs (IF it even occurs). Should congestion subsequently occur, traffic with a higher priority is handled first, followed by lower priority (and this is not a throttle to X speed)

I hope this helps. You can others can feel free to contact me directly if you have any questions
Regards
Jason Livingood
  - Engineering & Technical Operation

For verification, you can find the original in the IP Archives. [listbox.com] Date of the email is 2008-09-24 12:37:35

Re:Dang...

So this only hurts the dumb.

Every bittorrent client I've ever used has easy to set upstream and downstream limits. Simply set your upstream and downstream to 65% and 75% of you're max connection and you'll never be slowed down.

Not such a bad idea

I can deal with that, it's fair and doesn't really stomp on anyone's feet. So what if users eat up all the available bandwidth? Just make it fair who eats up more than others.

Re:Not such a bad idea

Yup. As someone who usually complain about these companies not doing things neutrally, I don't really have anything to stand on this time. This is basically how it should work. It is the network neutral way of doing things. Don't analyze the type or destination, but instead just look at the traffic you are causing. If you are using more than your fair share, you get put behind the one who has used less.

There only is so much bandwidth during primetime and to divide fairly among all users you have to do something. The system mentioned in the article is about as fair as you can get. It doesn't matter if it is video streaming or bittorrent, you shouldn't be able to use more than your fair share. Yes, high quality video streaming is probably hit, but that is because it is an incredibly wasteful type of technology, requiring high bandwidth during primetime when the user online.

Of course, you can still complain about comcast not providing enough last mile bandwidth, having a too high oversubscription ratio, but that is a different matter. As an actual packet prioritizing scheme, this is a good one.

Re:Not such a bad idea

I agree. This way of load balancing seems incredibly fair. However, the first time I get close to the 250gb cap, I'm heading over to Qwest and finding out how much an FTTP install costs.

Which is EXACTLY the way the free market is intended to work. Comcast gets the business they want, and Qwest gets to sell a service they offer.

Free markets, FTW.

Re:Not such a bad idea

I must not have read that properly. Did you just say that telcos and cable companies are free market?

Backwards?

Users who are found to be occupying large amounts of bandwidth will be placed at a lower priority for network access behind users with less bandwidth-intensive traffic

So they're saying that if I am doing something that requires more bandwidth, I will get less bandwidth; and when I don't need much bandwidth, they're going to give me more? I'm really confused by this. Can anyone make sense of this for me?

Re:Backwards?

No, it means that bulk transfers are lower priority than someone checking email, since that's fairly low load and interactive.

Re:Backwards?

when I don't need much bandwidth, they're going to give me more?

Prioritization is not the same as giving you more bandwidth. You packets are just dispatched through their servers faster than the lower priority ones. The net effect is that you get less bandwidth when the routers are overloaded (which is VERY sensible), but when the routers are not overloaded then you will get the quicker speeds (at least, that would be a fair understanding of how it *should* work).

The theory is that casual users are more deserving of the higher speeds and more appreciative of getting content quicker, whereas somebody who is spending 15+ minutes downloading a single thing is going to be more forgiving that it takes 4 hours instead of 2 hours to arrive.

Personally, I think Comcast's goal is to degrade internet streaming video to the point where it matches their cable services with the "Occasional 5 Second Pause" (TM) where the service goes apeshit and becomes unusable.

Full disclosure: I won't give Comcast a dime, and am waiting patiently for more capable internet to come to my neighborhood. Value = price + quality... and IMHO Comcast is simply a bad value.

OK, but can we help?

Low priority for large transfers is fine with me, but can we mark which data should be high priority? So we can download a movie from Comcast-Buy-A-Movie-Service in the background while online with Halo 3?

Re:OK, but can we help?

RFC 1349 [faqs.org] describes how you can specify priority for IP packets:

The types defined in the RFC are:

• minimize delay
• maximize throughput
• maximize reliability
• minimize monetary cost
• normal service

I believe an extension also had a "maximize security" option as well.

Alas, almost nothing supports these flags, and I believe a later RFC has proposed reusing the QOS bits in the IP header for an incompatible use.

Legal use of big bandwidth paying the price...

1) User pays for their own broadband access (cost of bandwidth). $$
2) User pay for Netflix a service contract (which includes more bandwidth costs). $$
3) User uses the bandwidth for which he paid by watching streaming movies and suddenly the movies don't load anymore... because it takes a bit of bandwidth to download movies.
4) User buys digital movies from Amazon et al? $$
5) User gets kicked from ISP because he paid enough to use what bandwidth he used.

Sounds like a scam to me!

Why offer high speed internet if you're not going to provide high speed internet?

Cool!

So when NBC or ABC/ESPN/Disney or CBS/Viacom or Sony Pictures or Time Warner comes to me and says "Look at our really great new streaming movie/TV/video service! Pay only $29.95/mo and you can watch anything anyTIME ALL THE TIME!!!", I'll say "Sorry. Can't do streaming video. It puts me in the Comcast doghouse. I just play Nethack."?

Ok

Re:Pretty sure this was in place for a while now

...As my cable modem service slows to a CRAWL if I have a torrent open for more than 20-25 minutes. Once you terminate the d/l, it stays that way for 20-25 minutes or so... The throttling is so severe that DNS requests time-out... Not really that awesome of a solution, IMO.

That's probably not throttling. Same thing happens to my cousin, and the same thing happens to me (though not as bad.) Every seed and leech in that torrent is still hammering your connection and timing out, requesting what parts you're advertising. At least that's what my firewall logs seem to suggest.

Power cycle your cable modem and get a new IP address. Your former cloud will no longer be DDoSing your connection.