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Cisco DPC3939B and Asus RT-AC68u - no IPv6 on LAN?

JonKMyers
New Member

Cisco DPC3939B and Asus RT-AC68u - no IPv6 on LAN?

I've been banging my head against this for a few hours now and have only been giving myself a bruise and a headache.

 

Here are the facts:

I'm a new Comcast Business Class customer with 1 static IPv4 address. I transitioned over from consumer-class as I wanted to be able to host my own email server.

 

The gateway is also receiving a IPv6 address, which is dynamic if other posts on this forum are to be believed.

 

The DHCPv4 server on the gateway is switched off; I've made the gateway into as much of a "dumb bridge" as I believe possible. My RT-AC68u is doing the firewall/NAT/wireless/DHCP on the IPv4 LAN side. The RT-AC68u is directly connected into the gateway on LAN1.

 

 

Here's a screenshot of the current IPv6 settings on the RT-AC68u:

RT-AC68u settings

 

 

As you can see it is not showing that it has a LAN address for IPv6. If I SSH into the router, it shows it has an IPv6 address from the gateway.

 

I've tried disabling DHCP-PD and setting it up as a second LAN device, but it mostly doesn't work - when my Windows 8.1 box says that IPv6 has Internet access, it apparently can't route packets beyond itself.

 

My PC's secondary NIC, when connected directly into the LAN2 port of the Cisco DPC3939B, receives an IPv6 LAN address from the gateway, no problem, and I am able to ping and otherwise conduct traffic to and from IPv6 Internet sites.

 

As a workaround, I can use a Hurricane Electric tunnel on the router but I'd prefer to use native support where I can.

 

Any suggestions? Other posts on this forum seem to suggest that the Netgear gateway is the way to go for native DHCPv6 on a LAN at the moment as the Cisco gateway is currently incapable of doing the correct DHCP-PD handoff.

Trusted Forum Contributor

Re: Cisco DPC3939B and Asus RT-AC68u - no IPv6 on LAN?

Hello JonKMyers and welcome,

 

If you have an IPV4 Static IP then it is necessary for you to use IPV4 across all your network equipment. You should be able to use your RT IPV4 standard staticIP configuration, disable your DPC IPV4 LAN, then use your RT DCHP Server. It is a very tricky networking situation trying to run both IPV4 and IPV6 simultaneously, but I appaud your initiative.

Comcast has not yet come out with the new IPV6 static IP information and is still working on this.

Hope this helps you out.

JonKMyers
New Member

Re: Cisco DPC3939B and Asus RT-AC68u - no IPv6 on LAN?

Nuts. Looks like HE has me as a tunnel customer for a while until Comcast gets their stuff together.

Trusted Forum Contributor

Re: Cisco DPC3939B and Asus RT-AC68u - no IPv6 on LAN?

TO add a bit more information, what you are looking for ideally is "sub-delegation" of a 2601::/64 prefix coming from the Cisco. At this time, they haven't managed to get that working yet on the Cisco; it IS working on the other 2 gateways, the SMCD3G and the Netgear CG3000DCR, so I imagine they are close to having it done.

LiFePO4
Visitor

Re: Cisco DPC3939B and Asus RT-AC68u - no IPv6 on LAN?

My understanding is the Netgear is the only one that can do sub-delegation at this time. The SMC does not but is being worked on.

Trusted Forum Contributor

Re: Cisco DPC3939B and Asus RT-AC68u - no IPv6 on LAN?

ok I stand corrected.

 

I am personally using my own modem with business class (no static IPs), and doing that gets you the same level of IPv6 service as residential (2001:558:6016:29::/128 on WAN, 2601::/56 prefix delegation for LAN)

webvictim
Visitor

Re: Cisco DPC3939B and Asus RT-AC68u - no IPv6 on LAN?

Yes - the SMC doesn't do prefix delegation correctly either at the moment.