[c-nsp] Ubr Docsis 2.0 Question

[ongbh at ispworkshop.com]

I think Paul is right. 3.2Mhz to 6.4Mhz is a Docsis 2.0 specific mod profile.

You can run a mix mode with UBR, but your 1.1 modems will not log onto a
3.2mhz channel width profile. Regardless, if it is 3.2Mhz QPSK.

The best I can think is to allocate 1 upstream port for DOCSIS 1.x and 1
upstream port for DOCSIS 2.0. Slowly move modems over, until you can ever
get rid of your DOCSIS 1.x modems.

In my personal experience, you can never get rid of DOCSIS 1.x modems,
depending on the size of your deployment.

I suspect in Arris, you are using the logical channel concept of DOCSIS
2.0 specification. I personally don't think it is good idea, given that it
might not be efficient, and from network planning perspective, how do you
plan your capacity in each logical channel.

On Tue, March 6, 2007 12:43 pm, Justin Shore wrote:
> I'm not a RF expert by any means but I'm pretty sure this is how we're
> actually doing it on our Arris C3s.  We've built 2 main modulation
> profiles, one ATDMA and on TDMA and associated them with different
> sub-interfaces of the upstreams.  The modems train up on the correct
> sub-interfaces.  This works like a champ for us.  I'm assuming that the
> uBR has a similar capability.
>
> Justin
>
>
>
>
> Paul Stewart wrote:
>
>> Following up...
>>
>>
>> I'm pretty sure you can run mixed-mode though with QPSK upstream on the
>> 1.x
>> modems and then 64QAM modulation for Docsis 2.0 modems on the same
>> upstream/downstreams?  This would be ideal even with the 3.2Mhz channel
>> size until we get a chance to swap out hundreds of cable modems...
>>
>> Thanks,
>>
>>
>> Paul
>>
>>
>>
>> -----Original Message-----
>> From: Michel Renfer [mailto:michel.renfer at finecom.ch]
>> Sent: Monday, March 05, 2007 10:39 AM
>> To: cisco-nsp at puck.nether.net
>> Cc: Paul Stewart
>> Subject: RE: [c-nsp] Ubr Docsis 2.0 Question
>>
>>
>> Hi Paul
>>
>>
>> No, of course not. Your DOCSIS 1.x (TDMA) modems will only support
>> channel-widths up to 3.2 MHz. If you want use the benefits of a 6.4 MHz
>> channel-width you need to use DOCSIS 2.0 modems (ATDMA).
>>
>> cheers, michel
>>
>>> -----Original Message-----
>>> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
>>> bounces at puck.nether.net] On Behalf Of Paul Stewart Sent: Monday, March
>>> 05, 2007 4:02 PM
>>> To: cisco-nsp at puck.nether.net
>>> Subject: [c-nsp] Ubr Docsis 2.0 Question
>>>
>>>
>>> Hi there...
>>>
>>>
>>> I'm pretty sure there's some Ubr experts on here ;)
>>>
>>>
>>> We are migrating a Cisco Ubr7114 up to Ubr7246VXR - so during this
>>> we'll be changing to Docsis 2.0 ... this will also involve changing the
>>> channel bandwidth from 3.2 to 6.4 Mhz....
>>>
>>> My question is in regards to Docsis1.1 modems - if we change the
>>> channel size to 6.4 is there a way to support modems that only work
>>> with 3.2 channel width (therefore Docsis 1.x)??
>
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