Ars Technica on IPv4 exhaustion

Kalnozols, Andris andris at
Mon Jun 23 03:32:40 UTC 2014

On 6/22/2014 7:41 PM, Frank Bulk wrote:
> Did they ever explain why?  Did the SMC function as a router, and act as the
> customer side of a stub network that allowed that /29 to hang off the
> router?  If that was the case, and the Motorola D3 modem was L2-only, that
> might explain the change in capability. 

They didn't really go into detail.  Your theory sounds correct; the
four ports on the SMC router default to but will also
handle a routable /29 address from the WAN side of another router
plugged into it.

Since Comcast now charges $19.95 instead of $9.95/month for a /29,
I inquired about the cost of an IPv6 assignment; same price as I
recall being told.  I then asked if that was for a /60 or /56 and
he said no, eight IPv6 addresses (/125?).  I politely thanked him
and ended the phone call.  I realize that I could have gotten a
more realistic answer from another Comcast rep with more v6-fu
but I didn't pursue it.


> -----Original Message-----
> From: NANOG [mailto:nanog-bounces at] On Behalf Of Kalnozols, Andris
> Sent: Sunday, June 22, 2014 9:29 PM
> To: nanog at
> Subject: Re: Ars Technica on IPv4 exhaustion
> <snip>
> My experience as a Comcast Business customer with a /29 IPv4 subnet was
> that swapping out the SMC modem/router for an IPV6-capable Motorola
> DOCSIS 3 modem meant that I could no longer have the /29.
> Andris

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