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CM1100 IPv6 Problem (Xfinity)
Hi everyone,
I replaced our C7100V with a new CM1100 yesterday. After a bit of wrangling on the phone with Comcast, it's activated and working... but only on IPv4. Firmware version after the Comcas...
CM is just a bridge modem. It is not do anything for CPE side (LAN side) Ipv6 other than just mere forwarding it.
Comcast does DHCPv6 for the routers and provides a delegated Prefix (PD) along with it.
Not sure what firewall you are using, but most linux ones support DHCPv6 with PD.
Update 2: Let's mark this as "solved," since the CM1100 is indeed pulling an IPv6 address. I'll continue working the issue with Untangle, since it's likely related to an issue with DHCPv6 / Native IPv6 / stateless / PD / RA, or a block of ICMPv6 traffic.
Thanks!
One final question about the CM1100 - will there ever be an ADVANCED > Advanced Setup > IPv6 settings page for the CM1100, like with other Nighthawk products?
Thanks!
I know little about IPv6, but ...
> [...] the CM1100 is indeed pulling an IPv6 address. [...]
The CM1100 is a modem, not a (modem+)router. What does it care about
IPv<Anything>? I'd expect a router, or your "our firewall (Untangle
v14.1.1)", to care about such things, but not a simple modem.> One final question about the CM1100 - will there ever be an ADVANCED
> > Advanced Setup > IPv6 settings page for the CM1100, like with other
> Nighthawk products?As with _which_ "other Nighthawk products"? Do you mean Nighthawk
(modem+)_router_ products? I wouldn't hold my breath.CM is just a bridge modem. It is not do anything for CPE side (LAN side) Ipv6 other than just mere forwarding it.
Comcast does DHCPv6 for the routers and provides a delegated Prefix (PD) along with it.
Not sure what firewall you are using, but most linux ones support DHCPv6 with PD.
vkdelta wrote:
Comcast does DHCPv6 for the routers and provides a delegated Prefix (PD) along with it.
Not sure what firewall you are using, but most linux ones support DHCPv6 with PD.
Thanks vkdelta (and antinode) for your responses. Unfortunately, finding someone at Comcast that knows anything about IPv6 is a chore. Tier 1 support is absolutely useless in this regard- the last one I spoke with didn't even know what DHCPv6-PD was, and could only give me the Class A IPv4 address. An informational IPv6 screen in the Advanced tab, or perhaps adding a line for "IPv6 Prefix Delegation" under Modem Status might help the more savvy user troubleshoot.
I'm using Untangle NG (v14.1.1), which is apparently having some issues with IPv6 in the current release. My options for IPv6 on the WAN side are Auto (SLAAC/RA), Static, or disabled. I'm hoping that I can statically set the prefix delegation (it does allow for changing prefix length), then use the first available address in the range on the internal side with RA enabled. I've got a PM off to a Comcast employee that's responded to IPv6 questions in the past- hopefully they'll be able to get me the PD info.
In the meantime, I'm going to dig around for an old router (I know I've got a WNDR3400v2- trying to find one with 100/1000 ports) that I can slap pfSense or WRT on to muck around with as an interim solution. Unless you want to keep this thread going, I'm going to mark vkdelta's answer as the solution to help keep the forum clean.
Thanks again, and happy Monday!