Is your ISP constantly changing the delegated IPv6 prefix on your CPE/router?
Imagine this scenario: you are sitting on the couch with your laptop open and all of a sudden there is a brief power outage. No big deal, a couple of your electronics will have to reboot and all is well.
However, if your CPE (modem/router) that connects your home to the Internet also reboots – you may have another problem. If you are connected to an ISP that implements IPv6 and is offering dual-stack connectivity to your home, interesting things might happen if your ISP did not configure IPv6 provisioning properly and decided to delegate IPv6 prefixes to your home in a dynamic way. So what are these interesting things?
If you are unlucky – your CPE reboots and your ISP delegates you a different IPv6 prefix than before, but because the CPE “hard reboot” it could not signal to your laptop/devices that the previous IPv6 prefix (and IPv6 address on your laptop that is from that prefix) is now gone and you can’t use it anymore.
To further add to the adventure, the majority of CPEs do not have persistent memory dedicated to storing your current IPv6 prefix in the case of a reboot. This means that there is no intelligence inside the CPE to inspect the new IPv6 prefix it has been assigned and deprecate the old prefix on your network. The CPE will instead just announce the new IPv6 prefix and your device is then free to choose an IPv6 address from the newly assigned prefix.
