New Poster
•
7 Messages
No longer getting an IPv6 prefix delegated
After a recent planned downtime for Comcast to make changes to the network in my neighborhood, I find that I am no longer getting IPv6 connectivity. I'm using a Cisco RV160W router. After digging in the router settings and doing some troubleshooting, it appears that I am not getting an IPv6 prefix delegated. This was working before the neighborhood network changes. Now, when I tell the router to use a "Prefix from DHCP-PD", it comes up with an address of fec0:1::0/64. I very much doubt that Comcast is handing me this, as it is a site-local prefix that was deprecated in 2004. Anybody else seen this?
If I call Comcast Tech Support, am I likely to have to fight the first-line tech support to get connected to someone who understands this issue?
XfinityVianney
Official Employee
•
1.9K Messages
1 year ago
Hi, @oloryn. Thank you for reaching out and creating a new post. I see after some updates in the area, you're no longer assigned IPv6 connectivity. I'm sure this has been confusing to see after not having this issue at all before, but we'll do our best to help work this out. I found a similar post HERE, where we discuss the specific setup and configuration. Can you review the instruction there to see if this helps you as well? Have you also tried releasing and renewing the IP Address?
1
0
zandor60657
Contributor
•
200 Messages
1 year ago
I bet your router is defaulting to a site local address range after failing to get a prefix, so it's not being assigned. I've seen something like this, but my router just straight up fails and I only get link local IPv6 addresses if it doesn't get a prefix.
You might be having the same issue I had with a MikroTik router. One of MikroTik's default firewall rules blocked DHCP v6 responses that did not come from a link local address. Comcast sends my DHCPv6 responses from a routable address on a different subnet. I've also seen posts in the MikroTik forums about the source address for DHCPv6 responses changing after Comcast did some upgrades. After fixing that firewall rule I'm able to get a /61. Supposedly you can get a /60, but I don't need that many subnets. I'm using 6, though one is IPv4 only since it's dedicated to a naughty weather station that will let you flash its firmware over WiFi using a phone without a password.
You're using a Cisco, which is likely far more configurable than a typical consumer router. Your Cisco and my MikroTik are both "business class" equipment. Usually that means you have full manual control of firewall rules. I'd check your firewall rules and see if there's anything in there about DHCPv6. If your router has a packet sniffer built in you can also try firing that up and sniffing DHCPv6 packets to get a better idea of what's going on.
3
0
user_sadie
5 Messages
1 year ago
I have Motorola MG8702 -- I'm not getting any IPv6 DNS addresses (it's blank on my router config) - although the setting is "enabled" which means it should be coming from Comcast/Xfinity. Where would a prefix setting be? I don't see that anywhere. Having an issue with my DNS for a few devices.
I too haven't called Xfinity ..... yet. They're going to blame my router. I've emailed support on my router, but pretty sure they're going to blame Xfinity.
1
0