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Comcast Trial IPV6 prefix delegation size.

New Contributor

Comcast Trial IPV6 prefix delegation size.


If I just attach my linux box and do dhcpv6, everything works.

I'm now trying to drop in a pfsense box as a router/firewall & have requested a prefix delegation of /56 from comcast.  How do I tell if my area is enabled for this?  It doesn't seem to be working. 


My linux box, of couse, gets a /64.


Edit: My pfsense box gets a /64 as well but anything smaller doesn't seem to work.

Re: Comcast Trial IPV6 prefix delegation size.

This is on our Netgear trial gear correct?  If so that is correct the Netgear is getting the /56 and is delegating a /64 to your pfsense box.

New Contributor

Re: Comcast Trial IPV6 prefix delegation size.

From reading these forums, I have to get someone at comcast to put my netgear comcast router into "bridge" mode so that I can get the /56 on my router/firewall instead of on the netgear itself.  I've also switched from a pfsenes box to an asa 5505 (Cisco) on 9.2 code. 


If this not possible & I need to wait, let me know.  I have no problem with ipv6 connectivity if I hook any device directly to the netgear box itself, but am hoping to get an intermediate router/firewall working that can have 3-4 interfaces, each with a /64 and begin testing.


Best regards,



New Contributor

Re: Comcast Trial IPV6 prefix delegation size.

My firmware was just upgraded.  I'm going to try this out tonight.

New Contributor

Re: Comcast Trial IPV6 prefix delegation size.



Did you get a chance to try this out?


I'm still struggling with getting PD's to work at all on the trial CCR. I went as far as to install an Ubuntu VM, wide-dhcp client, and various dhcp client and radvd configs.


With the lack of information on the Netgear CD300DCR trial for IPv6, all I can do is surmize:


  • It gets a /56 from the CMTS or Comcast BCI DHCP servers and presents that on the LAN;
  • my router (Ubuntu) pulls a /64 which it allocates to my "WAN" interface;
  • using wide-dhcp and a prefix of ::/64 I can get it to allocate an IA_PD for my "LAN" interface;
  • Via radvd my LAN hosts can see the /64 and autoconf and have a defailt gateway (to the fe80:: address, but the ubuntu box does route the traffic back to the CCR via the WAN interface)
  • No response from the LAN originated traffic (ping6 to Google) whereas the same ping from the WAN interface does work;

Latest firmware version ont he device still has the same affect.


I think at this point it's probably best for me to procure a supported modem (Arris) that is DOCSIS 3 and IPv6 capable for my production BCI. I can live with /60's and dynamic IPv6 at this point. I reckon the regular CCR's/CCM's on production HCI will have full support soon.


Now to find out about that bridigng mode. Smiley Wink

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