Tuesday, March 26

It’s time to move to IPv6. Many ISPs have already rolled out IPv6 or are in the process of doing so. If you’re the typical consumer, you don’t have much to do. But my blog isn’t geared towards the typical consumer. Like me, you probably have enterprise-grade router sitting at your edge. I happen to have a Cisco 1921. My ISP, Spectrum (Legacy Time Warner Cable), has deployed IPv6 completely in the area I’m located in. Other parts of the Legacy Time Warner Cable network may not have IPv6 fully implemented yet and other areas such as Legacy Bright House Networks and parts of Legacy Charter have no IPv6 connectivity yet.

Some things to note:

  • This assumes DHCPv6 from your ISP (in my case, Spectrum). If you have a static block or your own block from ARIN, this process won’t work.
  • You have a cable modem capable of IPv6 (if it’s modern, it should)
  • Your devices are IPv6 capable
  • We’re going to focus on establishing IPv6 connectivity, not worry about ACLs

Configure your router

Get into global config mode

config t

And go to your WAN interface. In my case GigabitEthernet0/0 is my WAN. Once there, add the following:

R1(config-if)#ipv6 address dhcp
R1(config-if)#ipv6 enable
R1(config-if)#ipv6 nd autoconfig default-route
R1(config-if)#ipv6 nd other-confog-flag
R1(config-if)#ipv6 dhcp client information refresh minimum 60
R1(config-if)#ipv6 dhcp client pd hint ::/64
R1(config-if)#ipv6 dhcp client pd SPECTRUM_PD rapid-commit
R1(config-if)#ipv6 dhcp client request vendor


Before we continue, I want to talk about this line: ipv6 dhcp client pd hint ::/64 What we’re doing is telling the router what prefix to request from TWC. In this case, a /64 or a single subnet. I’ve heard that you can attempt to request more, but I haven’t messed with this yet to find out. Since one subnet works for me at home, I’m sticking with this.

Now let’s head over to our LAN interface, mine is gig0/1. From there, enter the following:

R1(config-if)#ipv6 address SPECTRUM_PD ::1/64
R1(config-if)#ipv6 enable
R1(config-if)#ipv6 nd other-config-flag
R1(config-if)#ipv6 dhcp server SpectrumPool

End to global config.

We need to add the DHCP pool to our router and enable IPv6 goodness.

R1(config)#ipv6 unicast-routing
R1(config)#ipv6 cef
R1(config)#ipv6 dhcp pool SpectrumPool
R1(config-dhcpv6)#prefix-delegation pool SPECTRUM_PD
R1(config-dhcpv6)#dns-server 2606:4700:4700::1111
R1(config-dhcpv6)#dns-server 2606:4700:4700::1001

There you go! DHCP provided IPv6 from your ISP.

Test connectivity

You can test IPv6 connectivity using Google’s IPv6 test.


About Author

Hi! I'm Travis and I love technology.

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