Comcast Preps a Docsis 3.0 Boost

DENVER -- Cable Next-Gen Broadband Strategies -- Following favorable results of recent Docsis 3.0 upstream channel bonding field trials, a Comcast Corp. (Nasdaq: CMCSA, CMCSK) engineering executive believes the capability will be production-ready by the end of March.

Speaking on an opening panel session at Light Reading Cable's event Thursday, Senior Director of Network Architecture Chris Bastian said Comcast has already completed a field trial with one of its cable modem termination system (CMTS) vendors and is on track to complete a second one with a different supplier by the end of March.

Comcast isn't disclosing the sites of those trials, but the new capabilities tested in those markets will remain in place and be ready to go if Comcast decides to start marketing speed tiers that take advantage of bonded upstream channels.

Comcast has been testing upstream channel bonding on its "Extreme" Docsis 3.0 tiers that, for now, cap the upstream at 10 Mbit/s. Upstream channel bonding would let Comcast raise that ceiling. At last year's event, Bastian said lab trials were producing "sustained" upstream speeds of 75Mbit/s. (See Comcast: Upstream Bonding Tests Yield 'Sustained' 75 Mbit/s .)

Comcast isn't saying how much speed it would add as upstream channel bonding comes online, but the technology certainly would give it a new weapon against competitors such as Verizon Communications Inc. (NYSE: VZ), which has already launched a FiOS tier supporting 35Mbit/s upstream speeds.

Regarding the field trials, Bastian says a technique called partial service mode has worked as expected when applied across bonded upstream channels. That comes into play if one channel has to be taken out of service temporarily due to high noise levels; the modem continues to operate normally using the unaffected upstream channels. The peak speeds of the modem would be lower, but the device would remain in service, Bastian explained.

— Jeff Baumgartner, Site Editor, Light Reading Cable

Jeff Baumgartner 12/5/2012 | 5:12:07 PM
re: Comcast Preps a Docsis 3.0 Boost

One thing to add here is that although Comcast is closing in on having upstream channel bonding capabilities, it doesn't necessarily mean they'll start beefing up the speeds on the upstream side right away, though they'll certainly have that option.

 One thing Chris did mention is that bonding channels in the upstream does make the existing D3 tier more efficient because there's much more capacity to tap into when mulitple channels are combined. In that scenario, an Extreme customer that's supposed to be getting a max of 10Mbit/s upstream will likely be getting access to more speed on average if channels are being bonded when compared to a customer who subscribes to the same tier in a market that lacks channel bonding. Still, I'd be curious to see some numbers that show the differences between the two scenarios, though. 

And this sort of thing isn't exactly foreign to cable. They've already been doing this sort of thing on the downstream. Fellow panelist David Knight, the director of data and telephony engineering at Cox San Diego, noted that the MSO uses D3 modems to support its top three tiers: 15Mbit/s down by 2Mbit/s up, 25/3, and 50/5.



Greg_D 12/5/2012 | 5:11:29 PM
re: Comcast Preps a Docsis 3.0 Boost

There is going to be a big push for channel bonding, and that is the save some capital on node splits before its too late, while other architectures can be reviewed and developed properly. 

There is a big push for more speed without spending a lot of capital on node splits.

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