DHCPv6 - How to troubleshoot Prefix Delegation



  • Hi,

    I'm struggling to get my pfSense setup to work with my ISP and IPv6.  I'm using Shaw (in Canada), and they're using the Arris XB6 similar to Comcast in the United States.  I've put the Arris box into bridge mode, and I can get IPv6 to work as long as I do not request a prefix, however if I request a prefix I lose my IPv6 address and I still don't get a prefix.  I've taken a brief look at the dhcpd.log but I'm just not seeing a lot of information there.

    The modem (which is still accessible in bridge mode) is able to get both an IP address and a prefix.  I've tried using that information to statically configure pfSense without success.

    Any suggestions on how best to troubleshoot this issue?


  • Netgate

    The first thing to do is to enable the debug output for DHCPv6 on the WAN interface config then completely reset the modem. Then look at the DHCP logs and filter on process dhcp6c.

    This is all a complex dance between whatever cockamamie config the ISP device is expecting (ISPs do stupid things), and making pfSense do the same steps.



  • Thanks.  That gave me the information I needed.  A few more searches later and I was able to adjust my configuration to resolve the issue.  I had been using IPv6 with Unique Local Addresses but didn't want to switch my configuration around until I was able to confirm everything was working.  Because none of my interfaces had "Track Interface" set, it wasn't actually requesting an address.  Once I set my LAN to track the WAN, I received an address and prefix.  Thanks!