Comcast IPv6 Trials

Paul Stewart pstewart at
Thu Jan 28 13:15:56 UTC 2010

That really makes sense - on an incredibly smaller scale (and I mean MUCH smaller scale), we operate cable modem in two small communities - currently we use 3 IP addresses per subscriber.  One for the cable modem itself, one for the subscriber (or more depending on their package), and one for voice delivery (packetcable).  If we moved even two of three IP assignments to native V6 we'd reclaim a lot of V4 space - I can only imagine someone their size and what this means...


-----Original Message-----
From: Richard Barnes [mailto:richard.barnes at] 
Sent: Thursday, January 28, 2010 7:47 AM
To: Kevin Oberman
Cc: nanog at
Subject: Re: Comcast IPv6 Trials

What I've heard is that the driver is IPv4 exhaustion: Comcast is
starting to have enough subscribers that it can't address them all out
of 10/8 -- ~millions of subscribers, each with >1 IP address (e.g.,
for user data / control of the cable box).

On Thu, Jan 28, 2010 at 12:55 AM, Kevin Oberman <oberman at> wrote:
>> Date: Wed, 27 Jan 2010 20:59:16 -0800
>> From: "George Bonser" <gbonser at>
>> > -----Original Message-----
>> > From: William McCall
>> > Sent: Wednesday, January 27, 2010 7:51 PM
>> > Subject: Re: Comcast IPv6 Trials
>> >
>> > Saw this today too. This is a good step forward for adoption. Without
>> > going too far, what was the driving factor/selling point to moving
>> > towards this trial?
>> SWAG: Comcast is a mobile operator.  At some point NAT becomes very
>> expensive for mobile devices and it makes sense to use IPv6 where you
>> don't need to do NAT.  Once you deploy v6 on your mobile net, it is to
>> your advantage to have the stuff your mobile devices connect to also be
>> v6.  Do do THAT your network needs to transport v6 and once your net is
>> ipv6 enabled, there is no reason not to leverage that capability to the
>> rest of your network. /SWAG
>> My gut instinct says that mobile operators will be a major player in v6
>> adoption.
> SWAG is wrong. Comcast is a major cable TV, telephone (VoIP), and
> Internet provider, but they don't do mobile (so far).
> --
> R. Kevin Oberman, Network Engineer
> Energy Sciences Network (ESnet)
> Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
> E-mail: oberman at                  Phone: +1 510 486-8634
> Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751



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