DOCSIS 3.0 Channel Bonding and You

DOCSIS 3.0 Channel Bonding and You

I’ve been a subscriber to Time Warner’s high-speed Internet service since we moved to Texas, largely because they were the only option we had when we arrived at our new home. Since then AT&T U-Verse has also become available (up to the 18 Mbps tier), but I’ve enjoyed pretty consistent and reliable service from Time Warner so I saw no reason to change — especially since AT&T requires a contract.

However, over the last few months our Time Warner connection has slowed to a crawww-w-w-wl. We’re on the Standard tier, which gives us 10 megabits downstream. That translates to about 1.25 megabytes per second of maximum download speed. Lately, though, I’ve been lucky to get anything faster than 400 KB per second. This is even coming from sites that I know have the bandwidth to serve up files as fast as you can take them, such as Microsoft (try downloading a Windows service pack to see what I mean). On top of that, downloading game demos and patches through my Xbox console or app updates on our Apple iDevices seemed to take a dog’s age.

Whenever I’d get suspicious that something was awry with our connection, I’d hop over to and check things out. Every time I’d get a report back that our line was humming along at 17-20 megabits, which is double what we pay for. This, I knew, was due to the PowerBoost effect. (PowerBoost is a cable broadband feature that gives you a burst of super speed for the first few seconds of any download.) That made it tough to get an accurate picture of what our true speed really was. But if I was testing out at near 20 megabits most days, surely my real-world speeds were pretty good too.


"Emphatically no, Brock."

Uhhh, yeah. Not so much. Quite by accident, after getting into a discussion on DSLReports about Time Warner’s upcoming upgrade from 10 Mbps to 15 Mbps on the standard tier (yay!), it was suggested to me that my slowness issues could be caused by congestion on the lines and that is actually a very poor benchmark of real-world speed. It was instead suggested that I try the speed and line quality tests at and Visualware. So I set off to do just that.

I was pretty annoyed to discover all those other speed tests reporting a usable real-world throughput of only 3.3 megabits per second, only a third of the speed I was paying for — and an exact match for the approximate 400 KB/sec I was seeing in various download scenarios. While my upload connectivity seemed pretty good (after all, how hard is it to deliver a paltry megabit of upload capacity anyway?), the download speeds were atrocious. Other users on DSLReports who live in the Dallas area confirmed that Time Warner’s lines are severely congested in this area, which means too many people are using the same nodes and overloading the QAM channels.

These folks also suggested a solution: get a DOCSIS 3.0 modem. At first I thought that was hogwash, since we’re only on the Standard tier and we don’t have any need for the DOCSIS 3.0 technology that would deliver the speeds offered by Time Warner’s 30-50 megabit tiers. But I was soon to learn an important lesson: no matter what speed tier you subscribe to, channel bonding — a DOCSIS 3.0 technology — is your friend.

Time Warner’s Dallas-area systems offer six downstream and four upstream QAM channels. If the channels are overloaded, a DOCSIS 3.0 cable modem can bond multiple channels together to provide one big pipe. That way, even if only a little data can get through each channel, bonding them together will allow you to push that data through multiple pipes at one time and thus work around that congestion. Only DOCSIS 3.0 modems can do this.

The old DOCSIS 2.0 modem that I was leasing from Time Warner, conversely, could only utilize one downstream and one upstream channel at a time and it’s forced to use the channel the cable company’s headend tells it to use. If that channel is overloaded, then you’re gonna see poor speeds, period — and there’s nothing you can do about it.

So, I decided, I’m going to solve this problem of slow speeds by purchasing a DOCSIS 3.0 cable modem. Time Warner wouldn’t lease one to me because I’m not a subscriber of their high-speed tiers, so buying a modem outright was my only way forward. As a bonus, purchasing my own modem gets me out of the upcoming new $4 monthly fee that Time Warner will soon begin charging to lease a modem from them. Faster speeds and a fee exemption? Sounds good to me!

It gets better. In another perfect convergence of circumstances, last week Time Warner updated their approved modems list to add a number of new DOCSIS 3.0 devices, including the Zoom 5341J. Rather than pay for the expensive Motorola SB6141, I can pay two-thirds of the cost and get the Zoom, and still enjoy the ability to bond 8 downstream and 4 upstream channels. Future-proofing indeed!

Channel bonding is go!

So that’s exactly what I did. We returned on Thursday night from a trip to Orlando and I didn’t really want to pay Amazon $9 to have the 5341J delivered on Saturday, so instead I went to Best Buy and picked one up after work today. When I got home, it was simply a matter of swapping out my old modem, calling Time Warner and reading them the 5341’s MAC address so they could provision it in their system. 15 minutes later the Zoom was showing a pair of solid blue LEDs on the front, indicating both downstream and upstream channel bonding was established. We were in business.

(Incidentally, it seems that Time Warner’s new modem lease fee is prompting a lot of subscribers to buy their own modems. When I called in, the first thing I heard was a prerecorded message saying “Have you purchased your own modem? Press 1 to speak to someone about activating it.” The benefit of this was that I didn’t have to wade through a phone tree to get where I needed to go.)

The new modem didn’t immediately deliver Internet connectivity, so I had to release and then renew the WAN IP address via my router’s control panel. Once I had done that, I had full access. Of course, I immediately went to run some more speed tests. This time, the results were much, much better: I was seeing a solid and consistent 9.58 Mbps down and 969 Kbps up, which is right there at the upper limit of what we’re paying for. And with all six downstream channels bonded, I’m not likely to see any hiccups, even once Time Warner boosts us to 15 Mbps down in the next month or two, as they are reportedly doing nationwide. Yes!

I learned an important lesson here about DOCSIS 3.0 and channel bonding. If you receive broadband Internet from a cable company (instead of, say, DSL or fiber), and if your speeds are utter crap, you might also want to consider a DOCSIS 3.0 modem if your provider supports channel bonding. It just might solve all your problems. And, for that matter, help you avoid paying an equipment lease fee!