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holmosapien's profile

Occasional Visitor

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9 Messages

Sat, Dec 7, 2019 11:00 AM

IPv6 routing on DPC3941B in pass through mode

We have a DPC3941B in pass through mode with static IPv4 and IPv6 addresses. I am having trouble getting IPv6 routing through the modem to our firewall.

 

There are three possible ways that this could work:

 

1. Put the modem in bridge mode and lose our statics. This will allow our Ubiquiti router to use DHCP6-PD straight from Comcast. We've had success with this in the past, but I'm hesitant to do this because we'd like to use our statics.

 

2. Keep the modem in pass-through mode, feed the modem its WAN and LAN address ranges using DHCP6-PD (this happens), and then our Ubiquiti device uses DHCP6-PD against the DHCP service on the Comcast modem to get its WAN and LAN addresses (this does not happen). We have the stateful DHCP6 option enabled in the modem, but that looks to be standard DHCP6 for clients using the modem as the router, not a DHCP6-PD server that would further delegate ranges to our firewall.

 

3. Use static routing. We assign our Ubiquiti WAN and LAN addresses within our delegated /56, and then configure a static route in the modem so that it knows where to send the traffic. This would be a great solution, but I can't see any place in the modem to configure IPv6 static routes.

 

What is the official method for getting usable IPv6 in pass through mode with statics? Do we really need to choose either static addresses or IPv6?

Responses

Official Employee

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348 Messages

6 months ago

Good morning, I did want to reach out to see if someone contacted you? I do see that our agents are still working on this issue for you, so we can go ahead and follow back up with you on Friday, would that be okay? 

Member

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41 Messages

6 months ago

yes, I have a few messages from different comcast folks. So far no real info other than "we're looking at it"

Official Employee

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508 Messages

6 months ago

i do see that we have multiple threads, all pertaining to the same issue. This can cause some confusion while we are working toward resolving this for you. No worries we are geared to ensure that we get all questions or concerns resolved through one thread especially when they are pertaining to the same issue your IPV6 routing. So I would like to take this down to one thread to avoid confusion and miscommunication. Which thread would you prefer to continue on from here forward? 

New Contributor

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10 Messages

6 months ago

Here we are a month later, the Tier 2 support stopped replying to my emails on August 21st. I've since sent to additional emails showing what is happening. Anything directly connected to the Cable Modem, gets an IPv6 DHCP address. I have a Router connected to the Cable Modem and it gets both an address and a Prefix Delegation. Assigning an address out of the Prefix Delegation to an inside interface on the router or anything beyond the router, and they can't get anywhere. I see the Cable Modem sending Neighbor Solicitations for these addresses to my Router, instead of routing to my Router so that it can send them on to the end system. I've provided PCAP files to the Tier 2 support engineer. They had the Cable Modem replaced on August 14th with one marked Technicolor instead of Cisco, same software same issues. Was constantly having IPv4 outages on a daily basis until September 4th since the Modem replacement, so I guess that has been corrected. But, here I stand with no IPv6 working. It was last known working on July 14th when I setup a server utilizing the Comcast IPv6 PD Space. Looks like I need an escalation of this issue to Tier 3. I've given the Tier 2 support engineer until now. August 21st to September 11th has been 3 weeks with no response. I don't know what number to call for an escalation, don't know where I can go look at a trouble ticket for escalation. And this forum will not let me login using Firefox, have to use Chrome to login.

Member

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41 Messages

6 months ago

I am 100% convinced that this problem will not be publicized since the folks that see it are a less than 1% of their customer base. Happy eyeballs solves the issue for anyone that may be experiencing it and doesn't know they're using v6. Comcast has been pushing for folks to use their CPE for a long time and this is a forcing function for some. 

 

Official Employee

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255 Messages

5 months ago

Thank you for sharing this experience. I know IPv6 can be challenging when issues happen, to say the least. I am sorry you have not heard back from Tier II but I will be happy to follow up on your account and do my part to help. Please send a private message when you have a chance so I can help. If you can include your name exactly as it appears on your account, your full-service address, and your account number? (or phone number) this will help me get started. 

New Contributor

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10 Messages

5 months ago

Sent a PM to Comcast_Joseph on September 15th, with requested details. Haven't received a response as of yet. Just tried to check on it, but

You have reached the limit for number of private messages that you can send for now. Please try again later.

 

Official Employee

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348 Messages

5 months ago

Good morning, I am so sorry for our delayed response and so sorry to see that we have not yet reached back out to you and our advanced repair team has not yet contacted you. I can only imagine how stressful this is for you and you have reached an amazing team to help get this taken care of. Since it has been a while, can you please send one more private message with your name, the full address, and the phone or account number? 

New Contributor

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10 Messages

5 months ago

I just wrote a detailed reply to a PM from SprinklrBiz1

 

Clicked on the Send Button or Whatever and get the message:

You have reached the limit for number of private messages that you can send for now. Please try again later.

 

This is no way to support customers. You have my email address, my cell phone number, my phone number because it is with the same account. Have been fighting to get this fixed since August 6th. While IPv4 works 98% of the time, I focus on IPv6 deployment with my clients. When Happy Eyeballs doesn't work, or the clients aren't on a system supporting Happy Eyeballs it is a mess. So I've basically had to disable IPv6 on my end. 

Contributor

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17 Messages

5 months ago

I continue to have this problem since my modem was replaced late 2019. The routing of IPv6 is broken... Is there or will there be a fix?

Member

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41 Messages

5 months ago

I have been told this is not even accepted as a formal problem by the team responsible for firmware. My guess is that this is not going to work in the foreseeable future. Comcast officially supports one /64 directly connected to their equipment, nothing more.

New Contributor

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10 Messages

5 months ago

Truly sad, because it was working without issues. Then the upgraded firmware and broke it. They won't rollback the firmware upgrade, so we are stuck researching other options. Moving back to an IPv6 Tunnel Provider.

Member

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41 Messages

5 months ago

Sadly, that's what I had to do as well - IPv6 tunnels, like it's 2005 all over again. 

Official Employee

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255 Messages

5 months ago

I will need to take a closer look at your account to provide the best possible support and to assist you accurately. Are you able to send a private message? Please include your name, service address, and account number.

Member

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41 Messages

5 months ago

Why? It's a problem that won't be fixed until either

1. There is a firmware upgrade accepted and deployed, which happens after someone actually identifies  this as an actual service impacting problem that you are willing to take responsibility for fixing, or 

2. Replaces the modem with a Cisco or Netgear (which then limits the customer to a puma based device or a device with significantly lower capabilities, with an identified long term service impacting flaw as detailed by me years ago - and never acknowledged - here)

 

Let's just call a duck a duck: IPv6 is a best effort service for anyone not using a comcast gateway as their first hop router. This would be a non-issue if the behavior was consistent across the devices that comcast requires business users with static services to use. As it stands, it works on some but not on others, so the user experience for a small number os us is "we had a service and you took it away", which, let's be honest, is a pretty crummy quality of experience.