Docis 3.0 modem question.

[Dane]

So I am trying to upgrade my cable internet from 15 down to my cable companies new package. 60 down and 3 up.

I have my own cable modem that I bought from them awhile ago. It's an arris wbm760A. Everywhere shows it as a docis 3.0. When I was talking to the cable company they lady said "you'll need a DOCIS 3.0 cable modem". I told her I did and she said "no, you don't".

So I log into the modem and found the following:

One place says DOCIS 2.0 and another says DOCIS 3.0. So which is it? I'd rather not buy another modem for a few months if I need to.

[Lord Zog]

This modem is a DocSIS 3.0. I had one on Videotron in Gatineau, QC and I am on the 60 down package. I got a newer Arris only after adding a phone line to the package, but the WBM760 was used on the 60Mbit package...

[Martog]

It's a DOCSIS 3.0 modem just by searching around and even states it is.  The Upstream Channel saying Docsis 2.0 means it's communicating with your ISP over 2.0 for some reason, perhaps they didn't do something right on their end.  Maybe talk to a Tier 2 or Tier 3 tech agent who might have a clue.

[Dane]

This modem is a DocSIS 3.0. I had one on Videotron in Gatineau, QC and I am on the 60 down package. I got a newer Arris only after adding a phone line to the package, but the WBM760 was used on the 60Mbit package...

  

Thanks for confirming!

It's a DOCSIS 3.0 modem just by searching around and even states it is.  The Upstream Channel saying Docsis 2.0 means it's communicating with your ISP over 2.0 for some reason, perhaps they didn't do something right on their end.  Maybe talk to a Tier 2 or Tier 3 tech agent who might have a clue.

Yeah I looked around and it all said 3.0. I'll call them tomorrow and get it upgraded to the faster internet and figure out why I got told otherwise.

[Martog]

  

Yeah I looked around and it all said 3.0. I'll call them tomorrow and get it upgraded to the faster internet and figure out why I got told otherwise.

 

They probably looked at the current connection and saw it was running at DOCSIS 2.0 so assumed the modem was only that, the rep's and Tier 1's aren't the most knowledgeable and quick to assume they are right.

[neufuse Veteran]

If your network CMTS still has DOCSIS 2 devices on the headend the upstream usually stays at DOCSIS 2 until all devices have been migrated. Something to do with the modulation techniques I duno, Comcast has their networks set up this way I know that for sure... downstream is all docsis 3 but upstream is DOCSIS 2 until they get everyone switched over.

 

Edit: had too look it up, DOCSIS 3 is mainly used for QAM 128 modulation, which most areas don't support yet even with DOCSIS3 in place due to FCC rules, radio interference et and most areas run using QAM64 modulation.

 

Some other technical differences:
DOCSIS 3.0 supports QAM128 for upstream traffic, while many DOCSIS 2 support only QAM64
DOCSIS 3.0 specs use 108MHz to 1.002GHz downstream, 5MHz to 85MHz upstream.
DOCSIS 2.0 specs use 88MHz to 860MHz downstream, 5MHz to 42MHz upstream.
 

[Dane]

They probably looked at the current connection and saw it was running at DOCSIS 2.0 so assumed the modem was only that, the rep's and Tier 1's aren't the most knowledgeable and quick to assume they are right.

Thanks!!

If your network CMTS still has DOCSIS 2 devices on the headend the upstream usually stays at DOCSIS 2 until all devices have been migrated. Something to do with the modulation techniques I duno, Comcast has their networks set up this way I know that for sure... downstream is all docsis 3 but upstream is DOCSIS 2 until they get everyone switched over.

Thanks, so I should get the new speeds right away then? I shouldn't have to do anything?

[neufuse Veteran]

Thanks!!

Thanks, so I should get the new speeds right away then? I shouldn't have to do anything?

You have a DOCSIS3 modem, upstream isn't the issue as most carriers use D2 for upstream, you can still bond the channels, it's just a D2 modulation. The ISP should be able to provision the correct config file, and it should download at the next modem reboot automatically via TFTP and be running at the provisioned speeds.

[Dane]

You have a DOCSIS3 modem, upstream isn't the issue as most carriers use D2 for upstream, you can still bond the channels, it's just a D2 modulation. The ISP should be able to provision the correct config file, and it should download at the next modem reboot automatically via TFTP and be running at the provisioned speeds.

Thanks.

[Roger H. Veteran]

As already mentioned upstream will be 2.0 beacuse most cable boxes are 2.0 only so they have to leave a 2.0 line card active for those devices as well.

 

As also already mentioned and confirmed, your modem is 100% DOCSIS 3.0.:D

[Dane]

As already mentioned upstream will be 2.0 beacuse most cable boxes are 2.0 only so they have to leave a 2.0 line card active for those devices as well.

 

As also already mentioned and confirmed, your modem is 100% DOCSIS 3.0. :D

Thanks.  I got it ordered today.  The person on the phone didn't say anything other than "You modem is already DOCIS 3.0 so the speed should be working!"  

[+Thayios Subscriber²]

Frankly I'm too intoxicated to r read through the thread to see if this has been answered. The channel bonding is the biggest factor, eight down and four up need to be able to lock I believe for up to 100 Mbps on docsis 3.0

[xendrome]

Frankly I'm too intoxicated to r read through the thread to see if this has been answered. The channel bonding is the biggest factor, eight down and four up need to be able to lock I believe for up to 100 Mbps on docsis 3.0

 

I think 6 down will support 100mbit, anything above that it needs 8 IIRC.

[Mr. Gibs]

I would get a tech to come out and check those signal levels, they're really close to the maximum acceptable limit for reliable DOSCIS 3 connections.

Your downstream power should be:

-7 dBmV to +7 dBmV "Recommended"

-8 dBmV to -10 dBmV / +8 dBmV to +10 dBmV - "Acceptable"

-11 dBmV to -15 dBmV / +11 dBmV to +15 dBmV - "Maximum"

Lower than -15 dBmV & Higher than +15 dBmV - "Out Of Spec."

Your SNR levels are decent, basically you want more than 33 dBmv. 30dBmv is the absolute minimum.

On the upstream side you want the power levels to be between +35 and +49. You're more than +54. This will force your cable modem to downgrade from 64QAM to 16QAM (as you can see it did with yours) which would lead to slower than expected speeds / packet losses.

 

I think 6 down will support 100mbit, anything above that it needs 8 IIRC.

Each channel provides 40mbps (theoretically 48mbps). So 6 down is about 240mbps to 300.

[+Thayios Subscriber²]

Haha in theory, then we equate for the outdated garbage infrastructure in this country. Wait this is neowin so may be Europe if so I apologize. Specifically Americas cable infrastructure is ancient and garbage.

[Mr. Gibs]

Haha in theory, then we equate for the outdated garbage infrastructure in this country. Wait this is neowin so may be Europe if so I apologize. Specifically Americas cable infrastructure is ancient and garbage.

You do realize that DOSCIS 3 supports 1gbps, and DOSCIS 3.1 supports well above that right?

The biggest problem with cable isn't that its old, it's that the cable companies tend to fill up their nodes very close to the maximum which saturates the bandwidth available or you have retarded neighbors with ###### cable lines / splitters / active return amps that introduce a ton of noise to the entire neighborhoods cable line.

And it's not like you have a giant co-axial cable that goes from your house to the ISP. It's just co-ax to the node, and from there its a multiple 10gbps fiber backend.

[+Thayios Subscriber²]

I do realize being as I do this for a living (and own the business that does so) but the more realistic scenario of this is that it rarely will hit those speeds. It does not in practical everyday use. There's a reason why I can saturate my node in my backyard and at my office with the proper equipment (and that's channel bonding) with much less than multiple 100 Mbps connections on my nodes.

The fiber in MOST cities is not new nor is the coax, it's stuff that has been resold by the local phone companies and such (at least in the USA) and wireline guys have pulled it further. The bigger cities all are getting new infrastructure but the old cities are getting the short end of the stick.

Different areas, different scenarios.

[Mr. Gibs]

I do realize being as I do this for a living (and own the business that does so) but the more realistic scenario of this is that it rarely will hit those speeds. It does not in practical everyday use. There's a reason why I can saturate my node in my backyard and at my office with the proper equipment (and that's channel bonding) with much less than multiple 100 Mbps connections on my nodes.

And the reason for that is because comcast oversaturates the main node.

You have Fiber that goes to the neighborhood node (usually this is on seperate 10gbps connections, one for upstream and one for downstream). Now every person in the neighborhood will connect to this node, which will saturate it. So what cable companies do is they segregate it out into multiple smaller nodes. But still each node is using that shared 10gbps connection so your real limits are lower than that.

So sure you're able to saturate it most likely because your cable company hasn't upgraded their main nodes bandwidth, which will affect all the other smaller nodes and your tap. In some of the newer areas where comcast has been upgrading nodes you can easily hit 300mbps + if you're on one of their xtreme plans. I think the most they offer is like 500mbps and thats still over co-ax. It's just all based on how much bandwidth comcast has allocated to the node in your neighborhood.

[Dane]

I would get a tech to come out and check those signal levels, they're really close to the maximum acceptable limit for reliable DOSCIS 3 connections.

Your downstream power should be:

-7 dBmV to +7 dBmV "Recommended"

-8 dBmV to -10 dBmV / +8 dBmV to +10 dBmV - "Acceptable"

-11 dBmV to -15 dBmV / +11 dBmV to +15 dBmV - "Maximum"

Lower than -15 dBmV & Higher than +15 dBmV - "Out Of Spec."

Your SNR levels are decent, basically you want more than 33 dBmv. 30dBmv is the absolute minimum.

On the upstream side you want the power levels to be between +35 and +49. You're more than +54. This will force your cable modem to downgrade from 64QAM to 16QAM (as you can see it did with yours) which would lead to slower than expected speeds / packet losses.

 

Each channel provides 40mbps (theoretically 48mbps). So 6 down is about 240mbps to 300.

Could it be because it's an older modem?  I called tech support for them and told them and they didn't seem to concererned. 

 

Them: "do you have outages?" 

Me:  "no..."

Them: "well the speed tests are good, so I wouldn't worry about it"

 

 

I dislike our cable provider and they are really the only option.

[Mr. Gibs]

Could it be because it's an older modem? I called tech support for them and told them and they didn't seem to concererned.

Most likely not. It's either something wrong with their equipment or the cable line from the tap (the little box in your front yard) to your modem.

Them: "well the speed tests are good, so I wouldn't worry about it"

Well like I said the downstream levels are still in spec, they're just really close to the maximum that they should be. If they do end up going over, you will end up with issues at which point I would call them and be like "I told you so."

I'm surprised they don't care about the upstream power levels but if you're only getting 3 up I guess it doesn't matter.

[+Thayios Subscriber²]

And the reason for that is because comcast oversaturates the main node.

You have Fiber that goes to the neighborhood node (usually this is on seperate 10gbps connections, one for upstream and one for downstream). Now every person in the neighborhood will connect to this node, which will saturate it. So what cable companies do is they segregate it out into multiple smaller nodes. But still each node is using that shared 10gbps connection so your real limits are lower than that.

So sure you're able to saturate it most likely because your cable company hasn't upgraded their main nodes bandwidth, which will affect all the other smaller nodes and your tap. In some of the newer areas where comcast has been upgrading nodes you can easily hit 300mbps + if you're on one of their xtreme plans. I think the most they offer is like 500mbps and thats still over co-ax. It's just all based on how much bandwidth comcast has allocated to the node in your neighborhood.

 

We're both getting at the same things just wording it differently. I've pulled fiber backhaul with AT&T (both my dad and my grandfather worked for AT&T and Lucent Technologies where I grew up playing in the COs) and Comcast crews I've done my fair share of work as well. I have multiple backhaul connections to both Comcast and AT&T at multiple locations that are directly linked - those are capable of 1GBPS easily because they are directly connected to the backbone. In the end, it still ends up on the backbone of the network no matter what path you take and what company you go with and they still throttle your connections for a reason. 

 

I'm not saying you're incorrect, you're correct in some regards but talking in theoretical speeds is what I was referring to with channel bonding - the bonding is what will make a higher speed that's sustainable without amping up the power past it's point of what it can be. Just a funny FYI, I can saturate a brand new node, that's a mile from the main office of Comcast here. They weren't too happy with that one when I tried.

 

The node path technology is so incredibly simple it's sad. I can take eight modems all with eight accounts in the same city, hook them up on the same node and kill the internet for everyone else (down the nodes path to BH) without Comcast even noticing. I actually ran with three bonded together in a load balancer scenario for two weeks just to see if they would notice at my old office location a few blocks over...nothing. I downloaded the entire TechNet library while I had that connection testing.

[Dane]

Most likely not. It's either something wrong with their equipment or the cable line from the tap (the little box in your front yard) to your modem.

Well like I said the downstream levels are still in spec, they're just really close to the maximum that they should be. If they do end up going over, you will end up with issues at which point I would call them and be like "I told you so."

I'm surprised they don't care about the upstream power levels but if you're only getting 3 up I guess it doesn't matter.

 

 

What kind of probelms would I get? Disconnects exactly? Just so I know when to call again.