Roundup of IPv6 Comcast-supplied devices - PLEASE STICKY THIS!!!

Please see my comments below... Thanks

Moderators, please sticky this so people don't waste a lot of Comcast support time and get all frustrated!!!!!

ROUNDUP OF COMCAST-SUPPLIED CABLE MODEM ROUTERS AND IPv6 USAGE

1) DO NOT READ THIS IF YOU DO NOT NEED A STATIC IPv4 SUBNET!!!

2) For those needing static IPv4 subnets, and wanting IPv6, YOU MUST RENT A COMCAST-SUPPLIED MODEM!!!!   There are only THREE Comcast devices that have ever worked (after a fashion) in a dual-stacked environment;

CISCO BWG AKA DCP3941B:

For starters: The DCP3939B is another version of this Comcast Gateway (CG).

IPv6 works ONLY in a "client-type" mode.  Meaning you can plug in devices to it and they will get dynamic IPv6.  But you cannot plug a router  (linksys, Netgear, etc.) behind it and get IPv6 to work behind the router.

SMC D3G:

Enabling IPv6 on this also only works in a "client-type" mode.  Meaning you can plug in devices to it and they will get dynamic IPv6.  But you cannot plug a router  (linksys, Netgear, etc.) behind it.  ALSO enabling IPv6 makes it unstable and it will start rebooting.  See my post "Using the SMC D3G with IPv6 and static IPv4" posted   6-17-2015 for an explanation

Netgear CG3000DCR:

IPv6 - PD works on this.  But the router CPU is puny and won't hold up to 100Mbt down by 25Mbt up.  Otherwise a dual-stacked router plugged into this works just fine.

Please obtain accurate technical information before posting it in this forum:  The Netgear 3000 CG is currently being utilized by MANY Comcast Business customers for Internet Speed Tier of 150 MegaBitsPerSecond (MbPS) Down and 20 MbPS UP.

CHOOSE YOR POISON!!!!    COMCAST HAS APPEARED TO CEASE WORK ON IPv6 deployments OTHER THAN deploying to END USERS.  

Again, I do not know what you base the above statement on but it has no technical or business validity whatsoever! So, I highly doubt this post will be provided as a sticky by any Forum Administrators for reasons stated above.  

The Netgear 3000 CG is currently being utilized by MANY Comcast Business customers for Internet Speed Tier of 150 MegaBitsPerSecond (MbPS) Down and 20 MbPS UP.

There have been NUMEROUS complaints in these forums from people who have had problems running this modem on high speed lines that say they cannot get full speed, and their problems disappeared when they switched to the Cisco gateway. These complaints were NOT in the IPv6 forums they were in connectivity and equipment forums.

I personally have not had problems with the device.  I ALSO recommend that if you are trying to work with IPv6 and the other devices that you try the Netgear.  However I recommend you keep your eyes open for any abnormalities when you do this.

And it is also a fact that the Netgear is not as easy for an end user to obtain from Comcast as the customer service people have to be aware of how to special order it.  I was told this when Ihad Comcast supply me with a Netgear.

Again, I do not know what you base the above statement on but it has no technical or business validity whatsoever! So, I highly doubt this post will be provided as a sticky by any Forum Administrators for reasons stated above.  

Comcast has NOT provided STATIC IPv6 access even though it has been requested for YEARS.  I have made posts in this forum complaining about this for years as have others.  Comcast has not also corrected the bugs in IPv6 with the Cisco devices or the SMC devices even though these bugs have been documented and acknowledged by Comcast employees.  The Cisco devices do not support IPv6-PD, that is a fact and has been posted about and known for over a year perhaps 2 years.

There has been plenty of opportunities for Comcast employees to publically post about the Cisco devices not supporting IPv6-PD or to post about IPv6-PD timelines and none have done so.

My statement stands that Comcast has given the appearance of abandoning further IPv6 deployment work.  You are WELCOME to post a refutation with EXPLICIT links to statements saying otherwise with SPECIFIC dates and times and commitments rather than just the public relations blather.

My experience with the Netgear modem:

IPv6 works fine as long as you receive a DHCP PD from the modem to your gateway. You can not use IPv6 unless you requested a prefix via DHCPv6. DHCPv6 is used to update the modems routing table, and you will see ICMPv6 errors (Type 5) if you try to use addresses.

In particular, if you reboot the modem, you will also need to restart the DHCPv6 client on your router (or restart the router) to obtain a lease.

As far as the stability is concerned: the modem works ok for me with 50MBit/sec, but after a couple of days the web admin interface stops responding (the modem will still pass traffic). To restart the web admin interface, the modem needs to be rebooted.

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@flybynight wrote:

 

IPv6 works fine as long as you receive a DHCP PD from the modem to your gateway. You can not use IPv6 unless you requested a prefix via DHCPv6. DHCPv6 is used to update the modems routing table, and you will see ICMPv6 errors (Type 5) if you try to use addresses.

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This by design I have this setup as well and it works great..  The Cisco router drops after about 3 months the DHCP lease {I dont know why} I do a clear IPv6 DHCP on that interface and all is good..

I think it is an IOS bug I do not have that problem and I'm running a Cisco 2811, see my other post with the config I'm using.