Issues with static IP with Technicolor CGA4131COM

Ever since I was switched to the Technicolor CGA4131COM I have been unable to get IPv6 to work properly. I recently went through a string of modems after the SMC modem I had started having RF issues. They then issued me a Netgear modem which worked great... except it would lock up hard about once a day requiring a power cycle, not good when I need to access my network remotely. Next, I was given a Cisco router that looks like the residential ones. This worked great after I figured everything out.

Recently I migrated my telephone service over to my Comcast business account to save money and I was forced to switch to the new Technicolor CGA4131COM. Ever since getting this modem I cannot get IPv6 to work properly. It does not like the fact that I have a router/firewall sitting behind it.

I have a static IPv4 address with one interface of my server and my firewall both plugged into the modem. The static IP address is assigned to my firewall and I use port forwarding to go from my gateway IP address to my server. My server is able to obtain an IPv6 address and work fine, however, my firewall is not. My firewall obtains an IPv6 subnet via DHCPv6 but no addresses behind my firewall are able to access the Internet. My firewall can ping IPv6 addresses. None of my IPv6 subnets, however, can access the Internet. I have traced packets going out of my router to the Internet, however, no packets are returning. It's as if the Technicolor doesn't recognize the fact that I have another router upstream of it. My router is a Mikrotik and I had all of this working with my Cisco modem. Any suggestions would be appreciated.

Responses

Comcast_Gabriel

Official Employee

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298 Messages

5 years ago

Welcome to our Business forums and thanks for taking the time to reach out to us! I would love to further assist with the port forwarding concerns. I have supplied a link here that will help you with the port forwarding concerns. https://comca.st/2v7hwLW As far as the IPV6 issue, here is another link that will help you with any information on that as well. https://comca.st/38tketx I am happy to assist with any further questions or concerns that you may have. Please reach out through private message with your first and last name, the full-service address, and account number or phone number and we will get started.

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aaron_w2

New Contributor

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5 Messages

5 years ago

I came across these threads:

https://forums.businesshelp.comcast.com/t5/IPV6/Can-not-get-internal-IPv6-traffic-to-route-with-the-CGA4131COM/m-p/39080#M1006

https://forums.businesshelp.comcast.com/t5/IPV6/Prefix-Delegation-w-CGA4131COM-working/m-p/37468#M965

This describes several bugs I have seen. Like this customer, I've had issues with the static DHCP leases in addition to the modem losing my static IP address entirely!!!

https://forums.businesshelp.comcast.com/t5/IPV6/Can-not-get-internal-IPv6-traffic-to-route-with-the-CGA4131COM/m-p/39412/highlight/true#M1050

This describes my problems exactly. Basically this modem is broken and can't do IPv6 prefix delegation routing. I want my older Cisco modem back. It had some issues but wasn't as broken as this Technicolor one. Unfortunately with my current plan that isn't possible. I have run packet sniffers and the modem just doesn't forward IPv6 packets to the delegated IPv6 block. It only forwards to individual hosts connected to it. As far as I'm concerned, this modem is not suitable at all for IPv6 without a firmware fix.

In addition, this modem lost my static IP address just like the other thread describes! This modem is definitely not ready for prime-time.

I have had a nightmare with modems. My SMC modem never delegated me a subnet for IPv6 then it had some RF issues. That was replaced by TWO Netgears, both of which would lock up daily (but when they worked, they worked). That was followed by a Cisco router which mostly worked, then I got this abomination.

I'm on my SECOND CGA4131COM because the first one lost my static IP entirely. I've found the entire process to be quite aggravating and have spent countless hours fighting with these gateways.

Now some background. I have written networking software since the 1990s with various technologies, including ATM, Ethernet, SONET and more. I've written low-level Ethernet drivers. I worked on software for a router accelerator. I also implemented the entire datapath of a high-speed router in a network processor's custom programming language. In addition to being a router, it was also an ATM switch, handled massive multicasting for IPTV and provided broadband remote-access server functionality for tens of thousands of subscribers with full traffic shaping, policing, policy based routing, MPLS, and a whole bunch of other stuff. It ran Cisco's operating system. I am currently debugging some 10G Ethernet issues with a custom ARM processor. My code runs on many well-known first-tier vendors hardware. Give me access to the code and I could probably fix the Technicolor myself (and add some needed features).

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Comcast_Gabriel

Official Employee

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298 Messages

5 years ago

Thank you so much for your time and patience! I also appreciate you for providing this information! It truly helps! I see that you have quite an awesome background there! I definitely want to help and explore all of the options that we have available to provide a solution to the modem concern. In order to look into this further, I will just need to pull up the account. Would you mind sending us a private message with your first/last name, full address, and account number or phone number?

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aaron_w2

New Contributor

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5 Messages

5 years ago

Sure, I'm not sure how to do that here. I can live without IPv6 but it's something I'd like to have working. I have a feeling the problem is that the modem isn't adding the route entry when something other than a /64 is given out.

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Comcast_Gabriel

Official Employee

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298 Messages

5 years ago

To send over a private message, please click on my handle (Comcast_Gabe) and you will have the option to send a private message. How does this sound?

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tralph1

Contributor

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19 Messages

5 years ago

I have the same issue. My packet captures show that my internal router forwards the packets out and then the modem does a neighbor solicitation (a layer 2 packet) trying to find the L3 interface which is behind the router.

It takes a basic level understanding of the OSI model to know that this will never work and is not how the modem should be working:

02:19:12.708251 IP6 2603:300b:XXXX:XXXX:208:a2ff:fe0c:e8e2 > 2606:4700:4700::1111: ICMP6, echo request, seq 33, length 16

02:19:12.722573 IP6 fe80::10:18ff:XXXX:c0ed > ff02::1:XXXX:e8e2: ICMP6, neighbor solicitation, who has 2603:300b:XXXX:XXXX:208:a2ff:fe0c:e8e2, length 32

Interesting to me is that even after disabling the firewall (as best we can in the UI) the logs still show:

FW.IPv6 INPUT drop , 31 Attempts, 2020/1/21 19:35:02	Firewall Blocked 	
FW.IPv6 FORWARD drop , 129 Attempts, 2020/1/21 19:35:02	Firewall Blocked

Clearly the firewall is not completely dead.

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CC_Michelle

Official Employee

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526 Messages

5 years ago

I am so very sorry to hear that you are having this issue with the static Ip's. I appreciate you taking the time to reach out through our business forums to let us know. I would love to assist. Can you please reach out through private message with your first and last name, full service address and account number or phone number?

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user_11313c

New Contributor

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1 Message

2 years ago

I know this is an older thread but I am having this exact issue and seeing these same things in my setup. Has there been any resolution for this as comcast support thus far has no clue what is going on or why the disabled firewall on the modem is still blocking traffic. Even to the point of telling me that my equipment was putting those logs there and it could not possibly be an issue with the modem. I am at a loss on what to do to get this resolved. Thank you for the help.

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