Internet Protocol Version 6
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IPv6 Lease only lasts 30 seconds? IPv6 unusable as a result.

The last couple days, I noticed an odd behaviour with my Comcast IPv6 address: I have to restart the DHCP client on my router every 30 seconds, or otherwise my IPv6 addresses are not considered valid. 


to reproduce:

- restart IPv6 DHCP client on my router

- ping from my workstation (behidn the router) works fine.

- after 30 seconds, I start receiving "source address failed ingress/egress policy" ICMP errors from Comcast's router

- I restart my DHCP client, and all is good again.


I had similar issues in the past, where I first needed to start the DHCP client to "activate" my IPv6 addresses. This has been an ongoing pain (for example, if I reboot the cable modem, I also need to restart the DHCP client). For a while, this was fixed, but now this is a new, even worse, behavior rendering IPv6 essentially unusable. 


I do have a static IPv6 assignment. Why do I need to jump through all the DHCP hoops? I don't have to do this for IPv4. And the current setup is just broken.

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Re: IPv6 Lease only lasts 30 seconds? IPv6 unusable as a result.

looks like the problem is solved now. Took about 50 minutes or so on the phone with support. Initially, the support person tried to explain to me that since my modem is up and "pingable", it had to be my problem. After some convincing and explaining that IPv6 is part of "The Internet" he dug deeper (call to level 2 support?) and figured out that my IPv6 prefix was double assigned. So essentially my modem and this other person's modem fought over it. Took them a while to find the second modem that shared my prefix (is Comcast running out of IPv6? 😉 ). So far, it looks like the problem is solved and I got my prefix back and working for about 5 minutes now.



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Official Employee

Re: IPv6 Lease only lasts 30 seconds? IPv6 unusable as a result.


Hi flybynight.


Glad to hear you were able to get this taken care of and addressed. Please do let me know if you need anything.

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