Comcast IPv6 Trials

Chris Gotstein chris at
Thu Jan 28 21:42:11 UTC 2010

Typically the CPE address is private, not sure why they would use a
public IP.  The MTA (VoIP) part of the modem would need a public IP if
it was talking to a SIP server that was not on the same network.  Most
smaller cable system outsource their VoIP to a reseller with a softswitch.

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Chris Gotstein, Sr Network Engineer, UP Logon/Computer Connection UP | +1 906 774 4847 | chris at

On 1/28/2010 7:44 AM, Joakim Aronius wrote:
> * Paul Stewart (pstewart at wrote:
>> 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...
>> Paul
> Excuse the newbie question: Why use public IP space for local CPE management and VoIP? Doesn't DOCSIS support traffic separation?
> /J 

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