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voipnpots

join:2011-10-13
USA

How many channels can be bonded over Docsis 3.0?

What is the maximum amount of bandwidth that can be achieved through channel bonding? Does channel bonding make use of existing channels, or are new ones added if needed?


TriForce

join:2008-05-27
Chico, CA
Reviews:
·Comcast
There is no set limit."Note that the number of channels a cable system can support is dependent on how the cable system is set up. For example, the amount of available bandwidth in each direction, the width of the channels selected in the upstream direction, and hardware constraints constrain the maximum amount of channels in each direction."


tshirt
Premium
join:2004-07-11
Snohomish, WA
kudos:5
Reviews:
·Comcast

1 recommendation

reply to voipnpots
Yes they can add channels as needed,
Though no home equipment can support it, demonstations have exceeded 4.5Gbps (128 channels bonded) down, and 385Mbps up.
these sort of setup COULD be use for commerial operations (think BIG enterprise) but the need for CMTS type equipment ($$$) rapidly makes direct fiber more practical to a single location.

4x4 or 8x4 channels should provide plenty of bandwidth for a very long time at all resdential and small businesses cable passes.

andyross
Premium,MVM
join:2003-05-04
Schaumburg, IL
reply to voipnpots
Using the current 256QAM modulation, each channel is about 42.8Mbit (I think closer to 38Mbit when overhead is accounted for). Currently, up to 8 channels can be bonded. It's now available in some areas, and newer modems support it. Most original modems only support 4 channels.

Upstream is about 30Mbit raw (27Mbit after overhead) due to different modulation. Also, since it has to sit below RF channel 2, you are limited to about 35-40MHz of bandwidth in the US. One channel is usually 6.4MHz, but can be divided to 3.2MHz if needed. Very low frequencies, below 10MHz, tend to be very noisy and are usually used by cable boxes as their return channel.

From the summary on Wikipedia, there is no limit to the number of upstream or downstream channels in the specs. If you used all the downstream channels in an 850MHz system (about 133), you could get about 5.7GBit (5.0GBit w/ overhead) if I did my math right.

As far as how many are used, it depends on the available bandwidth on each individual system. All available are on-line and not dynamically turned on or off like OnDemand.

voipnpots

join:2011-10-13
USA
reply to voipnpots
Great information - thanks. It seems like when you get to the GB level, it's better using a dedicated fiber/ethernet connection instead of bonding many channels, etc.


telcodad
Premium
join:2011-09-16
Lincroft, NJ
kudos:15

1 edit
FYI - I found this article on extreme DOCSIS channel bonding:

Quick: 1 and 4.5 Gig DOCSIS Explained
DSL Prime / DOCIS Report - June 16, 2011
»dslprime.com/docsisreport/163-c/···plained-

"ARRIS at the 2011 cable show demo'd 4.5 gig down by eliminating any TV programming and using the full bandwidth (128 6-MHz channels) for data. Comcast bonded more than 25 channels and showed 1 gig down and 300 meg up. These are improvised demos, not close to production equipment. It will take two to five years for gear that would make this practical for regular customers; lots of other obstacles beside the technical mean you will not see these speeds at home for a very long time."

And this report on that 2011 cable show by CED Magazine:

@ The Cable Show: Comcast gets to 1 Gbps on its Chicago network
CED Magazine - June 17, 2011
»www.cedmagazine.com/news/2011/06···-network

voipnpots

join:2011-10-13
USA
I sense FTTH once Comcast's practical limit is reached for these speeds (in 5-10 years once they've maxed out their current infrastructure). But it would be a heavy investment and I assume it would roll out very slowly (like their Home Security service).


motorola870

join:2008-12-07
Arlington, TX
kudos:4
reply to andyross
said by andyross:

Using the current 256QAM modulation, each channel is about 42.8Mbit (I think closer to 38Mbit when overhead is accounted for). Currently, up to 8 channels can be bonded. It's now available in some areas, and newer modems support it. Most original modems only support 4 channels.

Upstream is about 30Mbit raw (27Mbit after overhead) due to different modulation. Also, since it has to sit below RF channel 2, you are limited to about 35-40MHz of bandwidth in the US. One channel is usually 6.4MHz, but can be divided to 3.2MHz if needed. Very low frequencies, below 10MHz, tend to be very noisy and are usually used by cable boxes as their return channel.

From the summary on Wikipedia, there is no limit to the number of upstream or downstream channels in the specs. If you used all the downstream channels in an 850MHz system (about 133), you could get about 5.7GBit (5.0GBit w/ overhead) if I did my math right.

As far as how many are used, it depends on the available bandwidth on each individual system. All available are on-line and not dynamically turned on or off like OnDemand.

I have never understood why some systems can't hit the RF 135 (861MHz) I know that your system for some reason can only push to 855MHz while mine can get to the 135 sweet spot. I think the charter system next to me might still only go to 134 as last I heard they had a QAM64 channel at 855MHz. I think it has to do with older equipment/interference. Some of the emergency/private use public networks run in the 860MHz-870MHz band area. Maybe your area has a network up in that range that is causing havoc on that carrier. There is no such thing as a 850MHz system only 860MHz and 870MHz systems in addition to 330MHz, 450MHz, 550MHz, 625MHz, 650MHz, 750MHz, 1GHz. You don't want to talk about systems that are still below 330MHz yuck 270MHz systems!

andyross
Premium,MVM
join:2003-05-04
Schaumburg, IL
It may be some of the cable boxes or other equipment cannot tune quite that high. My TV can go to 135, as can my RF Modulator (used to send the DVR's signal to a bedroom TV), but it didn't work well. I don't know which one was not working right.
Expand your moderator at work


eatnaders

join:2005-04-07
San Jose, CA
kudos:1
reply to voipnpots

Re: How many channels can be bonded over Docsis 3.0?

The next generation silicon is complete and newer modems will have a 16x4 chip with a wideband tuner. Coming soon to a store near you.


JigglyWiggly

join:2009-07-12
Pleasanton, CA
that's stupid
I want 16x16
it's time for cable to go semetrical or at least 2:1
Expand your moderator at work

andyross
Premium,MVM
join:2003-05-04
Schaumburg, IL
reply to JigglyWiggly

Re: How many channels can be bonded over Docsis 3.0?

said by JigglyWiggly:

that's stupid
I want 16x16
it's time for cable to go semetrical or at least 2:1

There is another thread about upstream bonding limits. The main issue is limited bandwidth available for upstream without MAJOR changes to hundreds of filters, amps, etc...


telcodad
Premium
join:2011-09-16
Lincroft, NJ
kudos:15
said by andyross:

said by JigglyWiggly:

that's stupid
I want 16x16
it's time for cable to go semetrical or at least 2:1

There is another thread about upstream bonding limits. The main issue is limited bandwidth available for upstream without MAJOR changes to hundreds of filters, amps, etc...

Yes, its at: »8 downstream 8 upstream modem?
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JPnATL

join:2011-11-16
Bethlehem, GA
Reviews:
·Comcast
reply to voipnpots

Re: How many channels can be bonded over Docsis 3.0?

I think Motorola has a modem out that supports 12 down and 8 up which I think it may be the SB6180 or something but the cable companies have not stabilized the bonded upstream yet so I wonder how that modem is selling.I had 3 bonded channels upstream awhile ago but it so far has not returned but like everything else the networking equipment is a galaxy in front of the service providers.Plus since in this country you can have 50 kids and let people like me pay for them,the exploding population will catch up with this as well I mean everybody should have cable broadband by the end of the next 5 years because if Obama gets it again it would not surprise me if me being the working tax payer would not have to start providing lazy wellfare junkies with cable broadband you know since its not fair if I have it and somebody else don't lol ok slightly off subject but its all connected.


EG
The wings of love
Premium
join:2006-11-18
Union, NJ
kudos:10
said by JPnATL:

I think Motorola has a modem out that supports 12 down and 8 up which I think it may be the SB6180 or something

FWIW, the 6180 is 8x4.


telcodad
Premium
join:2011-09-16
Lincroft, NJ
kudos:15
reply to JPnATL
There is no current US DOCSIS 3 modem that I know of that can bond more than 8 channels down and 4 channels up.

You can see the Motorola series here: »www.motorola.com/Video-Solutions···nd-eMTAs

As EG said, the Moto SB6180 (»www.motorola.com/Video-Solutions···80_US-EN) can bond "up to 8 downstream channels and 4 upstream channels." The same for the SB6141 (»www.motorola.com/Video-Solutions···41-US-EN).

Neither of those are on Comcast's "List of Approved Devices" (»mydeviceinfo.comcast.net/) however.

The only approved Moto device that can do 8 down and 4 up is the SBG6580 wireless cable modem gateway (»www.motorola.com/Video-Solutions···/SBG6580)

While there are some new DOCSIS 3 chipsets that can bond more than 8 downstream channels (»www.lightreading.com/document.as···lr_cable), the current, 5 to 42 MHz cable return-path can't support 8 upstream channels, see: »8 downstream 8 upstream modem?


DarkLogix
Texan and Proud
Premium
join:2008-10-23
Baytown, TX
kudos:3
Besides there still plenty of room in that 5-42 range for cleanup work to maybe someday allow higher modulations to inch out a bit more before they go and consider messing with the whole plant

so say they squeeze out 6 channels (which would need an * up bonding modem because they seem to go in multiples of 4)

then up them from QAM64 to 128 to 256 and likely a ton of work cleaning up the return path at each step to get it to work.


telcodad
Premium
join:2011-09-16
Lincroft, NJ
kudos:15
Yes, see this thread from a year ago: »QAM 512/1024
and this excellent presentation by Cisco's Ron Hranac on return-path design and troubleshooting: »www.ciscoknowledgenetwork.com/ca···ting.pdf


DarkLogix
Texan and Proud
Premium
join:2008-10-23
Baytown, TX
kudos:3
Ya, I think it'll be awhile but it just goes to show at some point they'll likely weigh the costs between widening the return path or cleaning it up enough to use higher modulations or just going to fiber when the time comes.


tshirt
Premium
join:2004-07-11
Snohomish, WA
kudos:5
Reviews:
·Comcast
And it won't be "a panic" when the time comes...
instead they'll see areas where further physical node splits will no longer be cost effective and begin haging fiber while keeping the system running on virtual splits, minor upgrades and other techinques. in the meantime each year the fiber/ducting gets closer to the home and the last 100 feet becomes easier and cheaper (think fiber to a nearby pole or off the strand and semi-fixed wireless to YOUR home gateway)
the transition will be almost invisible to the user(other than the new wireless gateway (for all services) and the press coverage.
Cablecos* will have little problem expanding bandwidth to ANY location where there is potential to return the investment required.

Extide

join:2000-06-11
84129
Why not just expand the entire network to 1.5Ghz and beyond? Put more upstream channels up there, along with downstream. The higher frequncy should allow more bandwidth also.


telcodad
Premium
join:2011-09-16
Lincroft, NJ
kudos:15

1 recommendation

said by Extide:

Why not just expand the entire network to 1.5Ghz and beyond? Put more upstream channels up there, along with downstream. The higher frequncy should allow more bandwidth also.

"just expand the entire network to 1.5Ghz and beyond"

There's a lot of time and money in that "just"!

Even if the coax cabling itself was OK with that, extending the HFC network to 1.5Ghz or higher would involve replacing alot of the other passive and active equipment in the system, including all the line amps and taps, much of which were originally designed to go out to "only" 750 MHz or less.


DarkLogix
Texan and Proud
Premium
join:2008-10-23
Baytown, TX
kudos:3
reply to Extide
said by Extide:

Why not just expand the entire network to 1.5Ghz and beyond? Put more upstream channels up there, along with downstream. The higher frequncy should allow more bandwidth also.

Also theres a reason that upstream is using low frenquancys
highs and lows are effected diffently by distance so having the differance so great allows for better tilt adjustments.


DarkLogix
Texan and Proud
Premium
join:2008-10-23
Baytown, TX
kudos:3
reply to tshirt
said by tshirt:

And it won't be "a panic" when the time comes...
instead they'll see areas where further physical node splits will no longer be cost effective and begin haging fiber while keeping the system running on virtual splits, minor upgrades and other techinques. in the meantime each year the fiber/ducting gets closer to the home and the last 100 feet becomes easier and cheaper (think fiber to a nearby pole or off the strand and semi-fixed wireless to YOUR home gateway)
the transition will be almost invisible to the user(other than the new wireless gateway (for all services) and the press coverage.
Cablecos* will have little problem expanding bandwidth to ANY location where there is potential to return the investment required.

Sounds fine exept for that crappy wireless part

I think it'll be better if instead they one day make 8 ring pairs at 100gbit then have network switches instead of peds with maybe gig or 10gig links to the home

and have some required device so they can rate limit it on the CPE rather than on the switch.
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