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Old 02-24-2011, 08:37 AM   #1
mitchelt
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Default DOCSIS 3.0 or 2.0 Modem?

On the Comcast page of compatible modems it says:

Performance Internet Package: DOCSIS 2.0 or 3.0


I am sick of leasing the modem for $7/mo and wanted to get a new one. I currently have a DOCSIS 2.0 modem

I was looking at these two modems and was wondering if it's worth the extra $50.00 to get the DOCSIS 3.0 modem...do you think I will see higher speeds?

Motorola SURFboard eXtreme Broadband Cable Modem - Model: SB6120: $100.00
Motorola SURFboard SB5101U USB Cable Modem: $55.00


Thanks!

Mitch
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Old 02-24-2011, 08:46 AM   #2
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Docsis2 technology is 10+ years old.

Go with Docsis 3.

If your using a really old modem, the new ones are going to have better built in tools (like a signal meter), better signal to noise ratio tolerance,,,, among other things.
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Old 02-24-2011, 10:32 AM   #3
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There is zero reason to use 2.0, your speeds will be severely crippled if you do. Make sure you get one that's on their approved and tested list.
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Old 02-24-2011, 10:39 AM   #4
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Thanks for the info....I did check the Comcast site and these are approved.

I will be going the DOCSIS 3.0 route!

Mitch
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Old 02-25-2011, 09:22 AM   #5
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I ended up getting the Motorola SURFboard eXtreme Broadband Cable Modem - Model: SB6120.

speedtest.net
before (avg.): Download: 9.84 Mbs / Upload: 3.53 Mbs
now (avg.): Download: 22.13 Mbs / Upload: 3.48 Mbs

It looks like Comcast is not employing the new DOCSIS 3.0 on the upload yet in this area…you can tell by the lights on the modem.

Thanks!!!

Mitch
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Old 02-25-2011, 10:33 AM   #6
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One of the difficulties that most user have is separating between Technological issue and functionality.

Technically Docsis3 is better and it might be that one day ISPs would say. OK No more, you can not use DOCSIS 2.0

However(currently)it is naive to think that in an environment that were bandwidth is controlled by the ISPs change to a better Modem (while your current Modem works OK) will increase your Bandwidth.

If the road from home to work is limited to 45 MPH it does not matter if you drive MiniCooper or Lamborghini.

P.S., using your own modem also exposes your to a scenario that the ISP will not support any thing pass the end of the coax that get to your door.

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Old 02-25-2011, 10:51 AM   #7
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Originally Posted by JackMDS View Post
One of the difficulties that most user have is separating between Technological issue and functionality.

Technically Docsis3 is better and it might be that one day ISPs would say. OK No more, you can not use DOCSIS 2.0

However(currently)it is naive to think that in an environment that were bandwidth is controlled by the ISPs change to a better Modem (while your current Modem works OK) will increase your Bandwidth.

If the road form home to work is limited to 45 MPH it does not matter if you drive MiniCooper or Lamborghini.

P.S., using your own modem also exposes your to a scenario that the ISP will not support any thing pass the end of the coax that get to your door.

So I guess the numbers I got from the various speed checking websites are all lying and that the increase in speed is not actually happening...I don't think so. I tested throughout the day and it was consistently faster.

As far insinuating that I am naive...I may very well be that, but implying that is rude, unprofessional and uncalled for.

Also...as far as not being supported by the ISP goes, that's a really lame comment coming from a moderator on this forum/website. So I guess you advocate people only buying computers from Dell or some other maker because if you were to build your own you would have no one to hold your hand if something went wrong.

In the 11 years that I have been coming to Anandtech, this is the first time I have ever gave it a thumbs down.
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Old 02-25-2011, 10:57 AM   #8
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Have you had Comcast for awhile now?
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Old 02-25-2011, 10:58 AM   #9
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Originally Posted by mitchelt View Post
So I guess the numbers I got from the various speed checking websites are all lying and that the increase in speed is not actually happening...I don't think so. I tested throughout the day and it was consistently faster.

As far insinuating that I am naive...I may very well be that, but implying that is rude, unprofessional and uncalled for.

Also...as far as not being supported by the ISP goes, that's a really lame comment coming from a moderator on this forum/website. So I guess you advocate people only buying computers from Dell or some other maker because if you were to build your own you would have no one to hold your hand if something went wrong.

In the 11 years that I have been coming to Anandtech, this is the first time I have ever gave it a thumbs down.
Jack was pointing out to other readers that you won't automatically get better speed by moving to a 3.0 modem. It all depends on what the provider supports. In your case the provider is using 3.0 and as such one could see significant speed increases based on what package you pay for.

Many people think newer is automatically better, but in this case it's beyond one's control and up to the provider.
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Old 02-25-2011, 10:59 AM   #10
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Have you had Comcast for awhile now?
Yes...for around 12 years.
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Old 02-25-2011, 11:04 AM   #11
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Quote:
Originally Posted by spidey07 View Post
Jack was pointing out to other readers that you won't automatically get better speed by moving to a 3.0 modem. It all depends on what the provider supports. In your case the provider is using 3.0 and as such one could see significant speed increases based on what package you pay for.

Many people think newer is automatically better, but in this case it's beyond one's control and up to the provider.
Well then Jack should a better job articulating what he is trying to say and not jump to conclusions. To take a page out of his book, it is naive to think you know everything about a specific situation.

If he asked some additional questions he may have realzied that in my Comcast Internet Service Tier they support both 2.0 and 3.0. I went from a 2.0 modem to a 3.0 modem so the speed increase was a fact.
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Old 02-25-2011, 11:10 AM   #12
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Yes...for around 12 years.
Yeah it's totally worth it then. But it is good for short periods of time to just rent.
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Old 02-25-2011, 12:22 PM   #13
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@ mitchelt, I might much older than you and naive myself in understanding the many Sub Culturals in the bizarre times that we are living in.

AFAIK Naive = "natural or innocent, and did not connote ineptitude".

Spidey (thank you) voiced perfectly my sentiment.

Quote:
Originally Posted by spidey07 View Post
Jack was pointing out to other readers that you won't automatically get better speed by moving to a 3.0 modem. It all depends on what the provider supports. In your case the provider is using 3.0 and as such one could see significant speed increases based on what package you pay for.

Many people think newer is automatically better, but in this case it's beyond one's control and up to the provider.


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Old 02-25-2011, 12:32 PM   #14
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@ mitchelt, I might much older than you and naive myself in understanding the many Sub Culturals in the bizarre times that we are living in.

AFAIK Naive = "natural or innocent, and did not connote ineptitude".

Spidey (thank you) voiced perfectly my sentiment.
Age has nothing to do with it, as a moderator you should be more tactful about your comments and think them through before making them.

As far as Spidey goes...perhaps he can volunteer to be your editor?
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Old 02-25-2011, 12:57 PM   #15
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Ok - let's play nice now. But what Jack said is true in MOST cases, just not yours. A D3 modem won't automatically give you faster speeds unless, like in your case, the provider is in fact using Docsis 3 and your tier has allowed you access to those speeds.

Each subscriber's modem is given a specific file that has settings dictated by the ISP. These settings tell the modem what the download and upload speeds are. What shocks me is that your D2 modem was only giving 9mb. I have a D2 modem with my cable ISP as well and I routinely get 30mb down and around 2mb up. I'm surprised that simply getting a Docsis 3 modem you had such a drastic increase in speeds compared to your old modem.

Unless of course, your old modem was in fact a Docsis 1 modem instead. Would you mind sharing the model number of your previous comcast modem?
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Old 02-25-2011, 01:07 PM   #16
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Unless of course, your old modem was in fact a Docsis 1 modem instead. Would you mind sharing the model number of your previous comcast modem?
I am past what Jack said...so enough about that.

I was also very surprised at the speed increase, the old modem:

Scientific Atlanta
Model: DPC2100R2
HW Rev: 2.1
Mfg Date: 11/06
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Old 02-25-2011, 01:55 PM   #17
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I've got a Docsis 2 modem and I can average around 20+. It's not completely impossible there wasn't something wrong with your previous modem. Cox cable requires you get a Docsis 3 for their "not easy to find" 50+ Mbs service, otherwise anything lower they say use their D2's.

On Jack's earlier statement's - nothing uncalled for there. Not sure why you took that news so poorly other than the naive statement - but it's not like he was singling you out as not being bright. What we wouldn't want to happen is someone finding this thread as reference and thinking that by buying the higher priced modem they will see improved internet speeds - which in reality that's simply just not the case. Jack stated that plain and simple.

I'll be the first one to come out and say you may have wasted $50 and should have bought the D2 modem and seen if that was any better. If not, you could have always returned it and bought the better one.

And as far as support goes for that modem - nowhere near a lame comment. They have no obligations really to help you if you had internet issues and it was for a cable modem that wasn't theirs. Maybe that ISP does help you, but not all do. It's a general statement and you do in reality open the door up for them to say "sorry - it's not our modem - can't help you."
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Old 02-25-2011, 02:09 PM   #18
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Quote:
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I am past what Jack said...so enough about that.

I was also very surprised at the speed increase, the old modem:

Scientific Atlanta
Model: DPC2100R2
HW Rev: 2.1
Mfg Date: 11/06
I think that's the same model I have actually. I usually can pull around 30mb or so through mine on the download. I'd say your modem was faulty and needed replacing.
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Old 02-25-2011, 02:09 PM   #19
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I'll be the first one to come out and say you may have wasted $50 and should have bought the D2 modem and seen if that was any better. If not, you could have always returned it and bought the better one.
That makes no sense...why would I buy a modem that does not have the latest and greatest capabilities so I am future proofing myself for when the day comes and I move up to the next faster speed that requires a 3.0 modem?

I am not an expert on this stuff, but from my research it looks like 2.0 does not have channel bonding and because my Internet Tier supports DOCSIS 3 channel bonding why would I not get a modem that supports it?

As far as supporting the modem...I guess you can carry that forward and they can tell you it's your computer causing the problems, after all it's not there computer.

Do you buy the absolute bear-minimum PC that should get the job done or do you buy more than what you need so you don't have to buy a new PC every 3 months as your requirements change?
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Old 02-25-2011, 02:21 PM   #20
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That makes no sense...why would I buy a modem that does not have the latest and greatest capabilities so I am future proofing myself for when the day comes and I move up to the next faster speed that requires a 3.0 modem?

I am not an expert on this stuff, but from my research it looks like 2.0 does not have channel bonding and because my Internet Tier supports DOCSIS 3 channel bonding why would I not get a modem that supports it?

As far as supporting the modem...I guess you can carry that forward and they can tell you it's your computer causing the problems, after all it's not there computer.

Do you buy the absolute bear-minimum PC that should get the job done or do you buy more than what you need so you don't have to buy a new PC every 3 months as your requirements change?
Well no offense but I don't see 20mb being channel bonding, I could be wrong though. What color are your lights on your modem, the colors tell you if you have bonded channels or not. Like I said, I have a docsis 2 modem, no bonded channels and am getting around 30mb downloads on mine.

Whether you wasted money or not is your own opinion but if you did upgrade to a tier that did have bonded channels (usually 40+mb/sec), your ISP should give you a new modem that's capable of those speeds on that tier. ISP's don't like having old modems on their system as it degrades the service and increases support calls.

As far as the support issues, yes, if you own your own modem, you do open up the possibility they won't support your issue because your not using one of "their" modems. My recommendation is if you ever call for support, don't mention it's your own cable modem and they probably won't notice. If they suspect a modem issue and they know it's not their modem, they will not help you any further and you'll be on your own at that its an issue with your modem or not.
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Old 02-25-2011, 09:34 PM   #21
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42/7 on D2 with 1 up and 1 down.

remember the D3's comcast rock require all channels up (one fails = retrain all 5 in a 4 down/1 up scenario - i know it is stupid). also 5 channels takes alot more time than 2 (d2 = 1up 1 down).

So you'll see more retrains every day - and they will take more time.

I see about 6-15 daily with D2 i saw about 2-3 - the time to retrain is about 30-50 seconds with D3. <15 seconds with D2.

I had D2 @ 42/7 (max symbol rate) it was great. then they swapped it out while i was gone and oh well. at least i get 50/10 powerboost to 100/10 . but it's not nearly as reliable. I am on the only person on a short run tap. underground. flawless signal.

its buggy firmware/headend that hurts
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Old 02-25-2011, 10:35 PM   #22
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@ mitchelt, I might much older than you and naive myself in understanding the many Sub Culturals in the bizarre times that we are living in.

AFAIK Naive = "natural or innocent, and did not connote ineptitude".

Spidey (thank you) voiced perfectly my sentiment.

When i swapped out my old DOCSIS 1.0 modem that I had been leasing from the cable company for years with a new DOCSIS 3.0 modem, I got a twenty fold improvement, at least.

So, at the very least you were wrong in saying that 'it is naive to expect a performance increase when upgrading to a new specification.'
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Old 02-26-2011, 02:26 AM   #23
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Keep in mind that the difference between DOCSIS 2.0 and DOCSIS 3.0 was only two things: channel bonding for both the upstream and the downstream, and support for QAM128 for the upstream. Downstream both use QAM256 so the maximum downstream throughput for a single 6MHz channel is 42Mb. QAM64 upstream is 30Mb, and QAM128 should be something like 35Mb (I don't have the specific number in front of me), but I've never seen anyone use QAM128. So for all practical purposes the only difference is channel bonding.

Given that most services are still well below 42/30, the advantage to channel bonding isn't really throughput, it's load balancing. DOCSIS 2.0 only supports a single channel, so 2-3 users on a fast connection can easily saturate a 6MHz channel. Since DOCSIS can't seamlessly reallocate on the fly (DCC requires a modem retrain), you're basically stuck with the people on your channel, so you better hope not everyone is trying to use their connections at once.

With channel bonding on the other hand, you'll be using 3-4 channels. The worst case scenario (everyone on the service trying to max out their connection) is still the same, but with a larger pool of users the average isn't as bad because your connection can't be dragged down by a very small number of the wrong people. Thus performance is more consistent on average. In the long run of course this enables higher performance beyond 42/30. The secondary benefit is that with systems like PowerBoost, bonded channels mean not only can users boost higher, but for the same reason that bonding benefits the average speed, bonding makes it easier to boost big by siphoning a bit of bandwidth off of multiple channels.

It's because we're talking about the average case however that not everyone sees immediate benefits. Most users with PowerBoost available should see some kind of benefit, otherwise the biggest benefit will be for those users with a particularly unlucky channel allocated to them. And of course this assumes a DOCSIS 3.0 headend; none of these benefits would be seen with a DOCSIS 2.0 headend.
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Old 02-26-2011, 07:33 AM   #24
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just don't live in an old ghetto neighborhood/apartments. too much noise for D3. D2 and D3 don't really live well together so the folks are pushing D3 to everyone as soon as possible to sell more bandwidth. keep in mind! less reliability with D3 especially in a mixed environment or ghetto apartments where people are doing their own hookups.

if you vpn/remote telework you will know the pains i am talking about.
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Old 02-26-2011, 09:46 AM   #25
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Well no offense but I don't see 20mb being channel bonding, I could be wrong though. What color are your lights on your modem, the colors tell you if you have bonded channels or not. Like I said, I have a docsis 2 modem, no bonded channels and am getting around 30mb downloads on mine.
.
Receive Light = Blue
Send Light = Green
*Blue indicates it is connected to bonded channels

Which is right in line with an announcement made by Comcast regarding 3.0 in the Denver metro area. They are also working on the Upload part.
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