Smart Pipes, Dumb Pipes and QoS

By now, it’s fairly clear that the high-stakes commotion known as “network neutrality vs. network diversity” is really just a more genteel version of “dumb pipe” vs. “smart pipe.”

What’s perhaps not as clear are the technologies angling into the heart of the matter — specifically “Quality of Service,” or “QoS,” the subject of this week’s “translation.”

But first, a quick review of the “neutrality vs. diversity” scuffle. On one side are the Dumb Pipe (“neutrality”) contenders. All bits are created equal, they say. All broadband networks should be “neutral.” No bits should be blocked or disrespected in any way.

The arguments for “network neutrality” come from companies like Inc., Google Inc. and Vonage Holdings Corp.

On the other side is the Smart Pipe (“diversity”) crowd — those who built, own and maintain broadband networks. That means cable and telephone companies. (Oh, the irony.) They maintain that all bits are not created equal. Some need special attention in order to work well. It’s not about blocking or degrading anything. It’s about flow control.


At the technological heart of all this is that awkward term: “QoS,” short for “quality of service.” As a descriptor, it’s just as tacitly negative as “network neutrality” and “network diversity” is tacitly positive.

Here’s why. If Service Offering A (voice) has “quality of service,” does that mean Service Offerings B and C (Web surfing and e-mail, let’s say) lack quality?

But wait, there’s more: The generally accepted term for services that don’t need special handling is “best effort,” which reeks of low expectations.

QoS, despite its lackluster name, is about the part of network management that is flow control. It goes like this: There are pipes. They are fat. The carrying capacity of a modern HFC (hybrid fiber-coaxial) plant, fully digitized, is 5.2 Gigabits-per-second worth of reconfigurable, reusable speed.

Many bits ride inside the fat pipe. Some are the bits that constitute a request for a Web page. Others are e-mail bits. Some are video bits. Some are voice bits.

QoS sorts the flow inside the pipe. Its job is to make sure each bit gets what it needs, from the pipe, in order to get where it’s going — and work as expected when it gets there.

QoS is already in use by those cable operators offering voice-over-IP services. Reason: Voice bits need to get where they’re going fast, and in order, because conversations are live. Disorderly arrival messes with the quality of the call.


QoS works differently, depending on the direction bits are traveling.

In the downstream (toward homes) direction, QoS works by prioritizing packets. Bits can be tagged with a priority, from zero to seven. Most voice-over-IP bits, for instance, carry a higher priority than, say, Web-surfing bits.

In the upstream direction, the QoS toolkit is bigger, because the upstream path is notoriously skinny and mean. Congestion is plausible. That’s why upstream QoS includes five different ways for bits to “reserve” a ride. They go by names like “unsolicited grant service,” “near real-time polling,” “UGS with activity detection” — which, happily for you, fall outside the scope of this translation.

QoS has a known parallel. It’s trite, but it works: The U.S. postal system.

When Customer Jane wants to send a piece of paper with words on it to someone somewhere else, she has two options. She can stamp an envelope, and drop it in the mailbox. It’ll get there when it gets there. Best effort.

Or, she can go to the post office, and spend a little extra for priority handling. Maybe she wants it there the next day. Or two days from today.

In that case, Customer Jane parted with the extra cash for priority handling. Notably, the “network diversity” side doesn’t exactly see it that way. They realize that it’s hard to justify additional fees, atop existing broadband fees, to add priority handling to the bits that constitute an advanced service.

Moreover, they’re interested in developing a new batch of customers. Let’s say, for the sake of plausible argument, that it’s any of the growing list of companies using broadband pipes to stream video, or offer voice services. Vonage is a known example.

What’s for sale? Network features, built into the plant. Like QoS — the “priority handling” for advanced services. The pitch would go something like this: If you want to send your video bits over the network we build and support and you want those video bits to act like video bits, not best-effort bits, we can help you with that.

That’s money talk. And that’s why there’s this big debate. It’s less about whether pipes are dumb or smart, and more about who pays for priority handling.

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