IPv6 Delegations - DHCP-PD?

Hi there! I'm so sorry for the delay. Due to increased volume, we're working to get to our valued customers as quickly as possible . Thanks so much for reaching out. You've absolutely reached the right place, and are in good hands. I will own this Issue for you and ensure that I provide the best help I can today. All I need is your full name, account number (follow link https://comca.st/33q0ck9, account number is at the top right)and address including city, state, and zip code exactly how it reflects on the bill, and I can help you with whatever questions or concerns you may have. To protect your account, can you send me a private note with your information. 

As someone who has had this issue, and has posted (frustrated) posts about this, here is what will happen:

- You post about a problem.

- One of the customer service bots will response (I call them bots because of the similar, elaborate messages not really saying anything but "contact me via PM").

- Often the PMs go unread (double check it!)

- They will tell you there is a ticket

- A tech may call you eventually (1-2 weeks in) and tell you that they can't help you.

I have turned off IPv6 in my network. It has caused numerous problems with Comcast's implementation.

Comcast has long ago been attempted to be a leader in IPv6 deployment, and they will often claim to have it deployed to all customers. But often, it just doesn't work. I think there is little incentive on Comcast's end to make it work. The IPv4 shortage is yet another way to prevent competition.

Hi there, thanks so much for taking the time to reach out to the Digital Care Team about your feedback regarding the IPv6 delegation. We do know how frustrating this has been for you and we can help look into this for you. Can you please send us a private message with your name and the full address to the account? 

From Comcast Michelle last night:

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Re: IPv6 Delegations - DHCP-PD?

Thank you so much for taking the time to reach back out to us. You are correct currently IPV-PD is not a service that we are supporting at this time. We do supply IPV addresses for our business customers as a courtesy included with the purchase of an IPV4 block of Ip addresses. I can understand your need for an expanded support of IPV6 services and while technology continues to improve we are doing all that we can to ensure that we are supporting and keeping on top of this technology. I will forward your feedback and concerns at this time I do not have a time frame or option to if this service or feature will be available with our business services. 

This is the confirmation I had been looking for. IPv6 and Prefix Delegation is not supported... This should help a lot of us on this forum that had been using it or are trying to use it now.

Thank you so much for your time and we are truly sorry for any frustration this may have caused you. I know that sometimes these types of things can be super frustrating and we do want to make sure that we provide your feedback as we are an amazing team to provide this kind of feedback as we are always looking for ways to improve the customer experience. If you do ever need anything else, please let u know as we are always here 24/7 for assistance and can handle every issue. 

That simply isn't true.  I have been using DHCP-PD for years now.  On a Netgear cable modem.  I have DNS PTR's on PD-assigned subnets so yes, they DO support it.

The issue is that Comcast doesn't code their own firmware and is at the mercy of companies like Cisco that write the firmware for them.  And these days there are an -enormous- number of customers who want an all-in-one device that tries to do wifi/routing/cable-to-ethernet-docsis-junk/yadda-yadda-yadda   That is, to put it accurately, there's an enormous number of cheapskates willing to buy an all-in-one product that does nothing very well because everything is a compromise.  And on top of that they rent them because they want to get someone from Comcast to set up their internal LAN network for free for them and they don't want to pay Geek Squad.  They use the fact they are renting a modem as a way to wedge into all kinds of off-topic questions to Comcast support.

These ISP routers are all built around crummy little CPU's that are barely able to handle the needs of just passing packets from interface to interface.  These cpu's are crummy because if they were more powerful they would need cooling fans and larger power supplies - you know, like your desktop PC does.  To load IPv4 translation, dhcp, and wifi management on top of that is just too much.

If you are NOT a static IP user and you want to use IPv6 PD then BUY YOUR OWN CABLE MODEM and set it BRIDGED ONLY.  Then use a REAL router like a Linux/Unix box behind it.  Comcast will hand you a ::/56 prefix and you are off to the races.  Their standard is to assign the first subnet in the /56 to their device which leaves you plenty more to subnet with.  So for example they hand you a /56 like 2603:3004:50d:9a00::/56 well their router is going to use something like 2603:3004:50d:9a00:bad0:c0ed:dead:beef as it's IPv6 address so you can then use 2603:3004:50d:9af0::/64 or 2603:3004:50d:9b00://64 and so on and so on for your internal subnets.  This is all on you to configure properly.

If you think you must have a static IP then WHY the heck do you need it?  If it is for file serving then setup with a dynamic DNS provider there are free ones out there.  And run the dynamic DNS client on your Linux/Unix router.  And put the works on a UPS so that the auto assigned numbering doesn't change.

There really are very few people who need a true static IP.  The main ones who do are running email servers or IPSec VPN gear or are dealing with ill-designed firewall applications that require a static IP.  But modern VPN gear based on OpenSSL can run with both sides dynamic, I have one setup on 2 dd-wrt devices that will call anyone who says no a liar.  And right now the biggest problem with e-mail on IPv6 is how impossible it is to blacklist a spammer who is transmitting via IPv6.  (yeah like you are ever going to create a usable blacklist out of a pool of IP addresses greater than stars in the galaxy)  And as for the ill-designed firewalled applications (like ADP, LLC) well the banking industry has gone to 2FA and they can get off their lazy azzes and follow suit.

On my Netgear cable modem on static IPv4 I have set "Disable firewall for True Static IP Subnet Only", "Disable Gateway Smart Packet Detection", "Disable IPv6 Firewall"  "Enable DHCPv6" "Enable Rapid Commit" uncheck EUI-64 addressing and then make sure on my router behind it (A Cisco enterprise device) I have my internal-facing interface configured with the next available ::/64 subnet, and I send dhcp-pd requests to the cable modem.  It works fine.  No my connection to Comcast isn't a gigabit the Netgear can't support that bandwidth.

It did indeed work with the Netgear modem. It even worked for a period of time with the Cisco modem I had, then I upgraded my speeds. With the upgrade came a new firmware on the Cisco modem and IPv6 DHCP-PD no longer works. 

My speed is now too great to go back down to the Netgear modem, I am also told those are very hard to get.

I don't buy the argument that the vendor of the modem is the problem. Comcast could very easily fix this problem as one of the largest cable modem consumers in the US. It worked in the past with the same modem and hardware. And yes I do work in the software industry for a Fortune 500 company, when a large enough customer complains things get fixed REALLY fast. Comcast would be that 'large enough' company to any of the modem suppliers that they use. 

It is not a priority for Comcast to fix this. It is not on the road map. There is no incentive, no large customer that spends enough $$$ to make this climb a priority chart.