Visitor
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3 Messages
Ye Olde IPv6 /60 Prefix Request
Like many others over the years, I've been trying to set up IPv6 with a /60 (or, dare I dream, a /56?) prefix. No matter what I've done, it's always /64. I've tried asking live chat and they can never answer. [Edited: "Language"], even talked to a retail employee some time back and he'd been trying to get it on his own service and got an internal runaround.
All I want is a /60 prefix, the way It's Supposed To Be. That's it. How do I make this happen?
There's 128 bits in an IPv6. Quit being stingy with four of them.
Accepted Solution
XfinitySara
Official Employee
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2.4K Messages
11 hours ago
Hey there, @user_eson09. Thank you for taking the time to reach out with this request. We understand your frustration, and I'm happy to provide everything I can find on this! Here are some ideas to start:
1. The "Dumb" Hardware Swap (The Mac Address Trick)
The most common reason you are stuck with a /64 is that our DHCPv6 server has "sticky" leases. It remembers your router’s DUID (DHCP Unique Identifier) and keeps handing it the same /64 it gave you three years ago.
- The Fix: Change the MAC Address on your router's WAN interface (cloning a different device's MAC).
- Why: This forces us to see you as a "new" customer/device, which often triggers a fresh look at the prefix delegation (PD) logic.
2. The "Hints" vs. "Requests" Problem
Many consumer routers "request" a /60 but don't explicitly send a Prefix Hint. If our server is configured to be "lazy," it defaults to /64 unless the client specifically asks for more.
- The Fix: If you are using prosumer gear (Ubiquiti, OPNsense, pfSense, OpenWrt), ensure the setting "Send IPv6 prefix hint" is checked.
- The Nuance: In pfSense/OPNsense, you often have to set the "DHCPv6 Prefix Delegation size" to 60 specifically in the WAN interface settings.
3. Debugging the IAID
In the IPv6 world, your router asks for an Identity Association for Prefix Delegation (IA_PD). If your router is sending a request for a /60 but including an old IAID (Identity Association Identifier), we might ignore the size request and just give you what’s "on file."
4. The "Retail Router" Reality Check
If you are using our provided "All-in-One" gateway, you are almost certainly locked to a /64. Those devices are hardcoded for simplicity.
- The Fix: You must put our gateway into Bridge Mode and use a third-party router that allows you to configure the DHCPv6-PD (Prefix Delegation) size manually.
5. Check your VLANs
Some ISPs will grant a /60, but only if we see multiple DHCPv6 Solicits or specific sub-interface requests.
- If you have a router like a Dream Machine or an Edgerouter, try setting the Prefix ID on your LAN to 1 and a second VLAN to 2. Sometimes the "ask" for the second subnet is what finally triggers the /60 allocation.
A Technical Reality Check
While it feels like we are being stingy with 4 bits, for an ISP, moving from a /64 to a /60 per customer actually changes how we aggregate our routing tables at the regional level. If you're on a legacy "tier" or an older CMTS (Cable Modem Termination System) in a specific neighborhood, that hardware literally might not be configured to hand out anything but /64s.
Please let me know if this helps!
2
EG
Expert
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116.3K Messages
2 days ago
They used to offer a /60 or /64 a few years ago, but they stopped. AFAIK, you can only hint for a /64 PD these days.
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EG
Expert
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116.3K Messages
2 days ago
Hmmm. Some market areas / systems must still be offering it. Thanks for that info !
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