Comcast routing problems December 16 2011 (resolved)

Update: The problems described below were resolved by Comcast around 11:00 AM Pacific time and have not recurred since. We’re cautiously marking this issue closed, but continuing to monitor it.

We’ve received scattered reports of high “packet loss” to a few Comcast locations (but not most). Packet loss can cause pages to load slowly in some cases.

Debugging of this with our network providers shows that the problem is within the Comcast network: one of their “backbone” routes between San Jose and Denver has high packet loss. Comcast is aware of the problem and working on it.

Since Comcast uses many different “routes”, this doesn’t affect most customers. If your connection does happen to use that route for some connections, though, we know this is frustrating.

For networking experts: We have made an effort to “route around” the problem by sending Comcast traffic to different network peers, but unfortunately Comcast ends up sending it through the same backbone route regardless of how they receive it. This is affecting network traffic for Comcast customers to many different locations, and we expect they’ll have it resolved quickly.