[ale] Comcast cable modem - incompatible?

Tue Oct 5 09:33:48 EDT 2010

No....  Mike was spot on 2 days ago.  DOCSIS 3.0 is the only one that supports IPv6.  Quote from link below...

"DOCSIS® 3.0 provides a number of enhancements, most notably, channel bonding, support for IPv6,and support for IPTV. Channel bonding provides cable operators with a flexible way to significantly increase speeds to customers, with compliant devices supporting up to at least 160 Mbps in the downstream and 120 Mbps in the upstream."

All Tier II ISPs will run out of IPv4 addresses sometime next year, which means that all Tier II ISPs will run at the very least, some sort of dual stack IPv4 and IPv6 environment within the next year across all of their markets, as well as implementing other transition technologies in an attempt to ease the transition to IPv6 while supporting legacy IPv4.  If it doesn't affect you yet, it will very soon.  There is no real downside to this except the $50-$100 for a newer cable modem, which in most cases is provided.  The faster speeds of DOCSIS 3.0 will also ease congestion, even if it doesn't result in higher bandwidth for you.  

All of the versions of DOCSIS "can" be backwards/forwards compatible, if implemented at the head-end to be compatible, not all that unlike every other progressing standard.  Think wifi... B, G, N compatibility is a requirement from the equipment vendors, but an "option" in configuration of the AP and end devices, not a requirement.  For instance, nearly all ISPs already do not allow DOCSIS 1.0 devices as this is very insecure from a theft of service perspective.  DOCSIS 3.0 implements some very key changes at the hardware level, so in nearly all cases, it is not just a software upgrade from 2.0.

Without upgrading their systems to DOCSIS 3.0, you will end up sharing public IPv4 ip addresses with other subscribers on a large scale (ie large scale NAT).  You want DOCSIS 3.0 to be deployed.  Even if it doesn't improve your service, it saves you from having degraded service in the coming years.... 

Don't just accept it, embrace it....  

One note, that actually pertains to the list, is System Admins should take the time now to plan for IPv6 on your systems, especially public facing web servers and AAAA records, and IPv4 literals in web pages, as more and more customers will be reliant on you supporting IPv6 in the next year or so, as these Tier II ISPs, and their customers, transition.  Also, it is probably a good idea to think of the effect a large scale NAT or dual NATs (most notably protocols with embedded IP addresses) may have on your system access, and attempt to prepare, as we'll probably see some of this in the next year as well.  

And with that, I step down from my soap box.

John

On Oct 5, 2010, at 8:51 AM, Jerald Sheets wrote:

> I know that some of the turnkey goodies like ipcop and smoothwall type things have basic traffic shaping.  Maybe finding out what they're using in their distro and just studying/implementing that piece?
> 
> --j
> 
> 
> On Oct 5, 2010, at 8:38 AM, jcpilman at gmail.com wrote:
> 
>> The four successive versions of the DOCSIS® cable modem: DOCSIS® 1.0, DOCSIS® 1.1, DOCSIS® 2.0, and DOCSIS® 3.0, provide increasing levels of capabilities and functionality, while maintaining multi-vendor interoperability and full backward and forward compatibility of DOCSIS®.
>> http://www.cablelabs.com/cablemodem/primer/
>> 
>> On Tue, Oct 5, 2010 at 8:21 AM, Jim Kinney <jim.kinney at gmail.com> wrote:
>> DOCSIS or DOCSIS3? The 3 matters.
>> 
>> On Oct 5, 2010 7:49 AM, <jcpilman at gmail.com> wrote:
>> > A quick look at the first few google hits for DOCSIS says that all four
>> > versions are fully forward and backward compatible.
>> > 
>> > On Sat, Oct 2, 2010 at 2:25 PM, Michael Trausch <mike at trausch.us> wrote:
>> > 
>> >> Comcast is gradually migrating their entire network to do DOCSIS 3, as
>> >> well as IPv6. I'd suspect that one of the reasons that they want
>> >> newer modems on the network is the ability to acquire IPv6 addresses
>> >> on the Comcast network. Their trials are going well, from what I have
>> >> seen.
>> >>
>> >> I've been on DOCSIS 3 service since just before the start of 2010, and
>> >> I have to say that I am really liking it. I am not getting the 70Mbps
>> >> that I used to, as that was something that I got as part of the trial
>> >> that we were in when I was in Dunwoody, but I have 30Mbps. I could
>> >> get the faster one, but I'm not willing to pay that much extra. :-)
>> >>
>> >> In any case, I'd recommend getting a new DOCSIS 3 modem anyway. The
>> >> SB5100 series is getting pretty dated...
>> >>
>> >> --- Mike
>> >>
>> >> On Sat, Oct 2, 2010 at 1:43 PM, Kaerka Phillips <kbphillips80 at gmail.com>
>> >> wrote:
>> >> > I wonder if that is just the Atl market which Comcast is taking to DOCSIS
>> >> > 3.0 - I use Comcast in the DC area and also have a SB5100 - a SB5101 in
>> >> my
>> >> > case.
>> >> >
>> >> > On Sat, Oct 2, 2010 at 1:12 PM, Paul Cartwright <ale at pcartwright.com>
>> >> wrote:
>> >> >>
>> >> >> On Sat October 2 2010, Lightner, Jeff wrote:
>> >> >> > I don’t think Comcast is just trying to get me to lease a new modem as
>> >> >> > the
>> >> >> > letter says I can buy one at a retailer. I’ve already priced
>> >> >> > replacements
>> >> >> > that do DOCSIS 3.0 (e.g. SB6120) that are listed as compatible on
>> >> their
>> >> >> > site. However, without them being able to give me good information
>> >> I’m
>> >> >> > loathe to do that because they can’t tell me why the current modem
>> >> isn’t
>> >> >> > adequate or why there is a need for a change on Oct 12th in the first
>> >> >> > place.
>> >> >>
>> >> >> wouldn't you want a modem that can do DOCSIS 3.0 ? it says up to 4 times
>> >> >> faster than DOCSIS 2.0...
>> >> >> I see one on Amazon for $80:
>> >> >>
>> >> >> Motorola SB6120 SURFboard DOCSIS 3.0 eXtreme Broadband Cable Modem by
>> >> >> Motorola
>> >> >> Buy new: $80.73
>> >> >>
>> >> >>
>> >> http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=SB6120&x=0&y=0
>> >> >>
>> >> >> --
>> >> >> Paul Cartwright
>> >> >> Registered Linux user # 367800
>> >> >> Registered Ubuntu User #12459
>> >> >> http://usdebtclock.org/
>> >> >>
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