Visitor
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5 Messages
Xfinity Network upgrade / DHCPv6 change
A couple of months ago I received a notice that Xfinity was upgrading its network in my area with a middle of the night disruption.
Next day, my IPv6 stopped working.
I tracked it down to a change in the way DHCPv6 server worked. It seems the address of the DHCPv6 server moved from a link local address to a public one.
This required a change in my routing equipment (Mikrotik). By default, communication with the DHCPv6 server for PD (prefix delegation, udp port 546) was allowing local addresses only for this service.
Can anyone at Xfinity confirm this?
Out of curiosity, what was the network changed that required this? Did you implement SDN or something cool like that?
-bandit.
XfinityBillie
Official Employee
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2.2K Messages
2 years ago
We appreciate your time in reaching out to us here on our Xfinity Forums. Routine maintenance wouldn't affect the DCHPv6 servers. Are you currently experiencing issues with connecting to the internet? Can you tell me if you are using your own modem, router, switch etc?
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bandito1200
Visitor
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5 Messages
2 years ago
Hi Billy,
Thanks for jumping in. I resolved the issue, as described above, so there are no current connectivity problems. I just wanted to share in case others ran into it. Also to see if any advanced tech folks had insight into the change on Xfinity's end.
In case it wasn't clear, yes, I am using my own modem, router, and wifi access points. In particular the router is Mikrotik, which has a default filter DCHPv6 PD only local addresses. That's what I had to change due to the network upgrade. I don't think any rfc's require local addresses for DHCPv6 PD. So its unclear why Mikrotik defaults to this, but so be it.
Yes, the Xfinity DHCPv6 PD servers appear to have shifted behavior, they now communicate via global IPv6 addresses exclusively, it seems, rather than local. At least in my area. No biggie, just had to tell my firewall.
I believe you that routine maintenance would not change DHCPv6 configuration. The Xfinity notice I received called it a "Network Upgrade" so it was something more.
-A
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