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DOCSIS

KDG, Cisco Hit 1Gig Cable Modem Speeds

11:00 AM -- Germany's Kabel Deutschland GmbH took Docsis 3.0 to the extreme in a trial that, it claims, achieved download speeds of 1.17Gbit/s using gear from Cisco Systems Inc. (Nasdaq: CSCO).

KDG conducted the field trail in a multiple dwelling unit (MDU) in Hamburg to test the limits of D3 -- it already offers a 100Mbit/s (downstream) wideband tier. (See Kabel BW Does 100M With Moto.)

KDG, which operates plant built out to 862MHz (pretty good since "upgraded" plant is built out to at least 750MHz), said the trial showed that the operator has plenty of spectrum to offer those speeds with enough headroom to handle more than 100 digital and 32 analog TV channels.

KDG said the speed tests were conducted on an individual computer as well as on a "multi-room solution" involving several PCs.

KDG didn't spell out how many channels it had to bond to achieve the 1Gbit/s-plus speeds. Given that KDG uses EuroDocsis and 8MHz-wide channels (North American Docsis uses 6MHz-wide channels) that can typically pump out in the neighborhood of 45 Mbit/s to 50 Mbit/s each, it's likely that the MSO had to bond between 20 to 25 channels.

So, as far as the modems were concerned, we're not talking about anything off the shelf. Today's top-end D3 modems can bond eight downstream channels, though chipmakers like Broadcom Corp. (Nasdaq: BRCM) have already been fiddling around with 16-channel prototypes. If 1 Gbit/s is considered the next leap in D3 technology, then you might expect 32-channel-bonding capabilities to be on the forefront. (See Broadcom Dips Two Chips in 800M 'Prototype' , Docsis 3.0 Enters the Gateway Era , and The Ultimate Cable Modem .)

So, how did Cisco get its Docsis modems and cable modem termination system (CMTS) to hit the speeds touted by the KDG trial? One industry source familiar with Docsis guessed that it was probably a "Frankenstein setup" assembled explicitly for the purpose of the trial.

We've asked Cisco for more color on how the trial was set up and will report back when we get those details.

— Jeff Baumgartner, Site Editor, Light Reading Cable

Jeff Baumgartner 12/5/2012 | 4:18:22 PM
re: KDG, Cisco Hit 1Gig Cable Modem Speeds

 

I received an interesting suggestion on how KDG and Cisco achieved this. Instead of bonding all those channels together at once,  it's possible that they combined three 8-channel bonding groups and the same RF, duct-taped together three D3-certified 8x4 modems, and linked them to a home-side gigabit router.  A bit different than doing a massive bonding, but the number of channels required to do this seems to be in the ballpark.  JB

Jeff Baumgartner 12/5/2012 | 4:18:13 PM
re: KDG, Cisco Hit 1Gig Cable Modem Speeds

Cisco responded today to note that its flagship CMTS, the uBR10012, was involved in the KDG trial, noting that they offer "the only system that supports bonding of 24 downstream channels."  (so, we were in the ballpark on how many channels were involved, though some other CMTS vendors may refute Cisco's claim... we'll see).


Also, Cisco mentioned that it can provide 1Gbit/s of bonding "at  scale" with its new 3G60 CMTS line card, which packs in 72 downstream ports and 60 upstream ports. JB


 


 

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