Comcast, Netgear Run Into IPv6 Glitch

Last week a number of Comcast subscribers had a serious hardware problem on their hands. Netgear modems in California suddenly stopped working. Specifically, owners of the Netgear CMD31T lost Internet service, and subscribers were given a lot of confusing information about why they were being left out in the cold.

Industry analyst Mike Demler first reported the issue on EE Daily News, and noted that he was told by a Comcast technician that his Netgear model was not designed to work in California. Demler’s modem had been working for two straight months, however, and a quick search on the Internet found a data sheet saying the modem should work for all major providers except Time Warner. A trip to the local Frys Electronics store confirmed other Comcast subscribers were having the same problem, and Demler quickly escalated his investigation by reaching out to the PR departments at both Comcast and Netgear.

Fast forward to today, and it turns out that the faulty modem problem is an IPv6 issue. Here’s the statement from Comcast:

Comcast is in the process of deploying IPv6 nationally, as noted on this site in great detail. We recently identified that the retail NetGear CMD31T device ships with and runs an uncertified version of firmware that exacerbates a critical IPv6-related defect. To ensure Comcast customers with these devices will continue to have uninterrupted Internet service, we have rolled back IPv6 temporarily in some parts of our network to give NetGear more time to address the issue. Comcast anticipates NetGear will soon address the issue for their retail devices, which we will test and deploy on an emergency basis.

Of course the Comcast/Netgear problem makes one wonder what other glitches we’ll see as the IPv6 rollouts continue. Comcast plans to have IPv6 deployed in half of its network by the second half of this year. Here’s hoping the migration progresses as (relatively) smoothly as the digital TV transition. I had concerns then too, but ultimately the shift proved largely uneventful.

Published by
Mari Silbey