Zen and the art of IPv6

I’ve been tinkering with IPv6 at home lately—using Zen Internet and a Cisco router feeding my own firewall, and I’d like to share what I’ve learned. Zen provides a /64 prefix by default, which works fine... unless you’re running a home‑lab with multiple subnets and static routing.

This post is a practical guide to get your router prefix‑delegated (PD) by Zen, and carve up addresses properly, without too much magic or drama.

Why IPv6? Why bother?

If you want to visit something like ipv6.google.com and say "nice"—or simply future‑proof your network—IPv6 matters. Zen Internet already supports it, so it’s a great sandbox.

Step 1: Enable IPv6 routing

On your Cisco router, enter configuration mode:

conf t  # enter configure terminal mode
ipv6 unicast-routing

That turns on IPv6 routing globally on your device.

Step 2: Add an IPv6 DNS resolver

I use Google’s public IPv6 DNS:

ip name-server 2001:4860:4860::8888

That ensures name resolution works over IPv6.

Step 3: Prep the dialer interface

Configure your WAN (dialer0) interface to accept Zen’s /64:

interface dialer0
 ipv6 address FE80::1 link-local
 ipv6 address autoconfig
 ipv6 enable
 ipv6 nd autoconfig default-route

This enables SLAAC and automatically sets up the default route from Zen.

Step 4: Assign IPv6 to LAN interfaces

Technically you could carve up the /64 and assign addresses like this:

interface <your interface>
  ipv6 enable
  ipv6 address <your static ip>/64

Congrats! You router is now configured! Woo. Here's a quick recap on the commands:

configure terminal
ipv6 unicast-routing
ip name-server 2001:4860:4860::8888

interface dialer0
 ipv6 address FE80::1 link-local
 ipv6 address autoconfig
 ipv6 enable
 ipv6 nd autoconfig default-route

But honestly, best practice is to use a /48 if you plan to run more than one subnet.

Bonus: Ask for a /48 from Zen

Zen supports prefix delegation of a /48. Just email ipv6@zen.co.uk requesting it. They’ll assign it—but your router must request it explicitly.

Step 5: Request that /48 via DHCPv6 PD

Back on dialer0, add:

configure terminal
interface dialer0
  ipv6 dhcp client pd ZEN-PD rapid-commit

That asks Zen to delegate the /48 and tags it ZEN-PD. From there, you can statically assign from that block however you like.

Full config snippet:

configure terminal
ipv6 unicast-routing
ip name-server 2001:4860:4860::8888

interface dialer0
 ipv6 address FE80::1 link-local
 ipv6 address autoconfig
 ipv6 enable
 ipv6 nd autoconfig default-route
 ipv6 dhcp client pd ZEN-PD rapid-commit

 

Test it out

Once your hosts have static IPv6 addresses from the /48, visit ipv6.google.com. If it loads, you’re live! No tunnel, no fuss, just IPv6 through and through.

Final thoughts

IPv6 can feel weird at first—but with native allocation and proper PD, it becomes tidy. Using a Cisco router + Zen’s /48 support lets you carve out static addresses cleanly, keep control, and still play with all the new toys. I’m using this layout for VLANs, firewalls, and dual‑stack clients—it just works.

If you’ve set up IPv6 differently, or want help carving subnets or automating firewall rules, drop me a comment. I’m always happy to compare notes. Just remember to firewall IPv6 - on all your devices!

About the author

Tim Wilkes is a UK-based security architect with over 15 years of experience in electronics, Linux, and Unix systems administration. Since 2021, he's been designing secure systems for a telecom company while indulging his passions for programming, automation, and 3D printing. Tim shares his projects, tinkering adventures, and tech insights here - partly as a personal log, and partly in the hopes that others will find them useful.

Want to connect or follow along?

LinkedIn: [phpsytems]
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