IPv6 and Cox Cable

[Bluewind]

I have been using Cox Cable as my ISP in the Northern Virginia area of the U.S. Cox provides native IPv6 support. I tried every possible WAN and LAN IPv6 configuration but could not get my LAN clients to talk via IPv6 to the WAN. IPv4 worked great.

Cox supplied an Arris cable modem that had multiple modems including bridged and routed. Routed was the default. As part of my experimenting I tried to setup the modem in bridged mode but that did not work and Cox would reset the modem to routed mode within 24 hours.

I decided to buy a Motorola DOCSIS 3.1 cable modem primarily to save money on the cable modem rental ($10 USD per month). I installed the new CM which has no routing capability, hence bridged mode is the default.

IPv6 suddenly starting working on the LAN. I tested the connection on a bunch of the IPv6 test sites. All results were perfect including not leaking the IPv6 address of the LAN clients. One site said that IPv6 ICMP was not working correctly but I have no evidence of any problems.

If you are having problems setting up IPv6 with Cox, buy a CM and set it up for bridged mode.

Setup:
WAN
DHCPv6
Prefix Delegation 60
Send IPv6 hint

LAN
IPv6 - track interface
IPv6 Interface - WAN
IPv6 Prefix ID - 0

DHCPv6 Advertisement - off
DHCPv6 Server - off

[xinnan]

IPV6 relies on ICMP to work properly, so its a good idea to pass IPV6 ICMP. 

Just 1 opinion.  I'm sure there are many. 

(OHHHHHH NNOOOOOS.  The sky is falling!  You have IPV6 on your network!)

Glad its working well.