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elitefx
join:2011-02-14
London, ON

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elitefx

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It's Possible: 25/2 on a Docsis 2 Modem

Thought you guys would be interested to see this. Apparently one lucky dude convinced Rogers to provision the Express 25/2 tier on a Docsis 2 modem. Couldn't believe it myself but here it is part way down in this thread. Kinda blows the need for Docsis 3 modem purchases out of the water for the 25/2 tier. The TPIAs must really have Rogers worried. Never thought they'd go this far to keep a customer. Don't know how well 25/2 would work on 1 down/1 up channel though.

»[Express] Going to cancel, what's Rogers going to offer me?
InvalidError
join:2008-02-03

InvalidError

Member

Nobody questions the POSSIBILITY of going that fast or even faster on DOC2. The difficulty is SUSTAINING those speeds during peak hours.

You can theoretically do roughly 38/28 on a DOC2 modem but on a busy node, your speed will be the first to go down the drain during peak hours while DOC3 can leverage the slack on other QAMs to keep speeds up.
34764170 (banned)
join:2007-09-06
Etobicoke, ON

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said by elitefx:

Thought you guys would be interested to see this. Apparently one lucky dude convinced Rogers to provision the Express 25/2 tier on a Docsis 2 modem. Couldn't believe it myself but here it is part way down in this thread. Kinda blows the need for Docsis 3 modem purchases out of the water for the 25/2 tier. The TPIAs must really have Rogers worried. Never thought they'd go this far to keep a customer. Don't know how well 25/2 would work on 1 down/1 up channel though.

»[Express] Going to cancel, what's Rogers going to offer me?

With most nodes being full of DOCSIS 2 users you won't experience sustained performance levels with a DOCSIS 2 modem at the peak hours window.

Taylortbb
Premium Member
join:2007-02-18
Kitchener, ON

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It's possible, but it makes you neighbourhood asshole. When there's only 38Mb/s on a channel and you can pull 25Mb/s the 100 other houses on the node are gonna have their speeds go to shit. Obviously those on DOCSIS 3.0 won't be affected as they have access to other channels, but there's lots of other DOCSIS 2.0 users still. And you're just out of luck if anyone else on your node has the same idea, no way you can both get full speeds. So DOCSIS 3.0 modems remain well justified.

TypeS
join:2012-12-17
London, ON

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As everyone has already said, no ISP ever stated DOCSIS 2.0 modems would not work on their DOCSIS 3.0 upgrade networks. They just don't want them on their networks, because they don't support channel bonding. And thus will try to consume all their speed on one channel and congest that channel they're on. Not to mention people with D2 modems will complain about not getting their subscription speeds and try to blame Rogers.

Honestly Rogers should just keep flat out denying D2 modems. For their own customers they offer to rent modems and TPIA customers for the most part don't want forced rentals, so being told to purchase a new modem shouldn't be a disappointment (when going from D2 to D3).

Teddy Boom
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join:2007-01-29
Toronto, ON

3 edits

Teddy Boom to InvalidError

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said by InvalidError:

You can theoretically do roughly 38/28 on a DOC2 modem but on a busy node, your speed will be the first to go down the drain during peak hours while DOC3 can leverage the slack on other QAMs to keep speeds up.

Isn't there some limitation in the modem that prevents the full upload speed? I see spec sheets and docsis chats that seem to indicate that [something like 2.7mbit/s upload is the highest possible with real modems, and something lower would be realistic ed.]. Obviously I've never done either myself, so I don't actually know the facts, but...
(more edits: the SB5101 data sheet says 30mbit/s, so I guess I'm wrong.. Maybe I was reading old Docsis 1.1 stuff.. Not really relevant anyway )
(the final edit: Here's the chat I was remembering: »docsis.org/node/69)

Anyway, the issue with Docsis 2 modems running at ~20-30mbit/s appears to be highly exaggerated. Rogers probably could manage things fine with D2 at 25/2 if they wanted to. And, it looks like they want to for their own customers!

Thanks elitefx, very interesting stuff!
Gami00
join:2010-03-11
Mississauga, ON

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it's not really a matter of possibility anymore.

it all depends on if rogers will allow any higher profiles on D2 Modems. the answer to this is No, they don't.
InvalidError
join:2008-02-03

InvalidError to Teddy Boom

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said by Teddy Boom:

Isn't there some limitation in the modem that prevents the full upload speed? I see spec sheets and docsis chats that seem to indicate that [something like 2.7mbit/s upload is the highest possible with real modems, and something lower would be realistic ed.]. Obviously I've never done either myself, so I don't actually know the facts, but...

Anyway, the issue with Docsis 2 modems running at ~20-30mbit/s appears to be highly exaggerated. Rogers probably could manage things fine with D2 at 25/2 if they wanted to. And, it looks like they want to for their own customers!

The main reason why upstream has been typically much lower is because cablecos were running return channels in 64QAM instead of 256QAM and using half-width channels instead of full 6MHz so return QAMs often run at only 10-12Mbps rather than their maximum ~30Mbps. As they upgrade their network, shrink node sizes, fix noise/equalization problems in the return band, they move to full 6MHz and 256QAM.

As for the "thing with DOC2 being highly exaggerated", try telling that to people who have local node congestion even with DOC3 because their local node is that heavily loaded.

Teddy Boom
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Teddy Boom

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said by InvalidError:

As for the "thing with DOC2 being highly exaggerated", try telling that to people who have local node congestion even with DOC3 because their local node is that heavily loaded.

The fact that it is happening for D3 modem users too could be taken as proof that the effect of doing higher speed packages on D2 has little to no effect.
InvalidError
join:2008-02-03

InvalidError

Member

said by Teddy Boom:

The fact that it is happening for D3 modem users too could be taken as proof that the effect of doing higher speed packages on D2 has little to no effect.

If DOC3 subscribers are affected, DOC2 ones get it even worse.
old sparks
join:2011-02-17
Greely, ON

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I'm glad Rogers will continue to provision docsis 2 modems - then I won't feel so guilty about selling my 5101 modem last week for $35.00.

Teddy Boom
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Toronto, ON

Teddy Boom

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said by old sparks:

I won't feel so guilty about selling my 5101 modem last week for $35.00.

Maybe I should put my price back up (on DCM425 of course, I don't have SB5101).. It does take a lot of effort to sell one--people need a lot of help with this confusing internet thing..

Taylortbb
Premium Member
join:2007-02-18
Kitchener, ON

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said by InvalidError:

said by Teddy Boom:

The fact that it is happening for D3 modem users too could be taken as proof that the effect of doing higher speed packages on D2 has little to no effect.

If DOC3 subscribers are affected, DOC2 ones get it even worse.

+1

These are basic network concepts. 100 people with 25Mb/s each sharing a 38Mb/s pipe is just asking for problems. DOCSIS 3.0 remains very necessary. A small number of people getting away with it proves nothing, 95% of users would not manage it without issues. And saying "I'm willing to put up with issues" isn't an excuse, because not only do you get issues you cause them for ~100 other houses.

Teddy Boom
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join:2007-01-29
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Teddy Boom

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said by Taylortbb:

+1

These are basic network concepts. 100 people with 25Mb/s each sharing a 38Mb/s pipe is just asking for problems. DOCSIS 3.0 remains very necessary. A small number of people getting away with it proves nothing, 95% of users would not manage it without issues. And saying "I'm willing to put up with issues" isn't an excuse, because not only do you get issues you cause them for ~100 other houses.

I would have said the same, based on theory alone. However, there are posters on these forums with specific back end cable systems experience who will tell you it really isn't the issue it is being made out to be.

The CMTS (or the modem itself?) has the ability to dynamically switch the connected channel. Also, consider the effect of speedboost on the network. If one user taking up 75% of available capacity was such a problem on a Docsis network, speed boost couldn't possibly work as well as it does.
yyzlhr
join:2012-09-03
Scarborough, ON

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This is likely just an IT error, whoever created the codes for the unlimited express tier probably forgot to code in the modem eligibility requirements for this particular tier. If they start seeing a huge number of representatives not enforcing business rules, they'll probably get around to creating a new product code that enforces the D3 requirement.

neuromancer1
join:2007-01-22
York, ON

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It's for sure possible but by requiring them for 25/2 it helps make TSI/Rogers pockets fatter. It's their way of squeezing more cash out of the customers that didn't flip for an expensive Docsis 3.0 modem. Even more ridiculous is that if we don't upgrade they will rip us off by keeping us on 18/512 and charging us for 25/2. I forget what DSLR member calls them Bellsavvy but it's true, this such Bell/Rogers move.
don_quixote
join:2008-04-17
Toronto, ON

don_quixote

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said by neuromancer1:

It's for sure possible but by requiring them for 25/2 it helps make TSI/Rogers pockets fatter. It's their way of squeezing more cash out of the customers that didn't flip for an expensive Docsis 3.0 modem. Even more ridiculous is that if we don't upgrade they will rip us off by keeping us on 18/512 and charging us for 25/2. I forget what DSLR member calls them Bellsavvy but it's true, this such Bell/Rogers move.

I still don't get how buying a DOCSIS 3 modem 'squeezes more cash' for Teksavvy. Teksavvy isn't laughing their way to the bank by charging for modems. I mean, can you still even buy a modem from Teksavvy? I'm not even sure, because every modem I've bought (DSL or cable) since switching to Teksavvy many moons ago was from elsewhere.

In any case, DOCSIS 2 constrains bandwidth for everyone else in the neighbourhood, so while it's 'possible' there are very good reasons why Rogers doesn't want to offer it.
InvalidError
join:2008-02-03

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said by neuromancer1:

It's their way of squeezing more cash out of the customers that didn't flip for an expensive Docsis 3.0 modem.

DOC3 modems are only $25 extra when bought new and reduces the likelihood that you will run into congestion by ~75%.

As has been repeated by myself and many others, there are several perfectly legitimate reasons for cablecos to prefer or require DOC3 modems for higher speeds. Both the cablecos and all their customers benefit from more even load-sharing between QAMs.