Can’t Wait For DOCSIS 3? Bond With 2.0 B


Talk about technology moving quickly: One of the bigger stories on the broadband side of the house got a predecessor, a new name, and then another new name -— all within the last few weeks.

It all started during a pre-National Show vendor briefing, when a maker of cable-modem stuff dropped the term “pre-three” into a conversation.

For context, here’s the exact sentence: “We think there will be significant demand for pre-three products — I don’t know if they’ll be able to wait.”

“They,” in this example, are cable operators. What they may not be able to wait for: Some of the goodies slated for the newest cable modem specification, known industrially as DOCSIS (Data Over Cable Service Interface Specification) 3.0.

“Pre-three,” then, is shorthand for broadband-related gear that contains some of the features of DOCSIS 3.0, but not all of them.


Hang on. Don’t get too cozy with “pre-three,” because that unofficial name has already changed — to “2.0 B.” (Marketers, before you freak, know these as industrial terms, necessary as internal guideposts to stuff that will help you compete.)

The “2.0” in “2.0 B” refers to DOCSIS 2.0, the most recent version of the specification.

The “B” stands for “bond” — channel, not James — one of the sexier ingredients of DOCSIS 3.0.

Why “2.0 B” and not “pre-three”? Because the cable-operator side wanted to assure that manufacturers would keep going with all of the features of DOCSIS 3.0, and not stop at the early version. (I personally think “pre-three” is catchier than “two-dot-oh B,” but nobody asked.)

Why is this even happening? Because there are four giant features crammed into the full DOCSIS 3.0 spec. Finishing all four takes time.

The map from finished specification to actual product goes roughly like this: Silicon vendors “tape out” a chip design, based on their interpretation of the spec. That design goes to the foundry (the “fab”), which makes chips. Manufacturers buy the chips, add other necessary components, and build products. Those products go to CableLabs for compliance testing.

From beginning to end, if nothing goes wrong, it’s 18 months to two years.

If the DOCSIS 3.0 specification were to come out today (all signs point to “imminent”), it’d be early 2008 before full DOCSIS 3.0 gear would be ready for market.

For many operators, that just isn’t fast enough. Operators competing internationally are up against 100 Mbps fiber connections; operators stateside have Verizon’s FiOS in their faces.

WHAT’S IN '2.0 B’

Ultimately, the operators involved in building DOCSIS opted for a three-channel bond in the downstream direction, a one-channel upstream and Internet Protocol Version 6 (IPv6) as the core components of what is now “2.0 B.”

Reasoning: The full, DOCSIS 3.0 spec stipulates a minimum of four bonded channels, for 155 Mbps of downstream speed (4 channels times 38 Mbps). But operators don’t always have four unused digital channels available for the bond. Most of them don’t need that much firepower right away. Why not start at a three-channel bond, and bump up from there? That gets you more than 100 Mbps downstream.

IPv6 is in there because some operators are starting to worry (understatement) about running out of IP addresses for all the broadband gear they’re putting in people’s homes. Cable modems, voice-over-IP adaptors, and some advanced set-tops have IP addresses; some of those devices have more than one address.

IPv6 (translated in the Sept. 5, 2005, edition), offers a way to correct that. It takes today’s total address space, of 4 billion IP addresses, to a number so big that it doesn’t make sense to write out. It’s a one with 18 zeros behind it. Everybody should be OK, as far as IP address space goes, once IPv6 is in place.


That leaves two features for the full DOCSIS 3.0 specification: Advanced encryption, to even further secure consumer Internet connections, and a plumbing feature known as “M-CMTS,” for Modular Cable Modem Termination System (translated in the Feb. 28, 2005, edition).

Without re-hashing the whole thing, M-CMTS makes it more cost effective to send video bits over the IP (cable modem) path, because right now it’s substantially more expensive than the digital set-top path.

Boil it all down, and it means this: With 2.0 B, operators get a fast track to better, faster broadband gear, and a fix to the IP address problem. Soon. Maybe even this year.

Manufacturers get a faster track to revenues, making products based on 2.0 B.

All the while, everyone keeps pushing to the full specification, with forward compatibility likely to be enforced by purchase contracts.

In short, everybody wins.

Stumped by gibberish? Visit Leslie Ellis at