Through network magic I know not much about, Pakistan has caused YouTube to be inaccessible from the majority of the world. It’s not just that they blocked access to YouTube from within their own country; they did it in a way that isn’t filtered by their upstream ISP, so it affects pretty much everyone else too. What happens now?
Well, this damage is going to be routed around pretty quickly, as Pakistan having the ability to knock off websites is an error that will shortly be corrected. I predict the fallout will be immense though. Censor sites and the world looks down upon you, but do it in a way that (temporarily) removes the rest of the world’s access, and you’re in another circle of hell.
Maybe Pakistan is about to find out what the true meaning of “Googlebomb” is.
Update 1: So after a little more edification, I think I have a better handle on what’s going on. First, read up on the AS7007 incident, because what’s going on now is essentially the same thing. The Border Gateway Protocol that the Internet uses to establish routes prioritizes specific routes over more general routes. A network in Pakistan set up a /24 route, which is about as specific as you can get (/25 and beyond are commonly filtered out), declaring that YouTube was located within their network. Since this was the most specific route, it propagated out across all the routers, and now most of the Internet thinks YouTube is located within that network in Pakistan. Of course, it’s not, and they’re simply dropping all of those packets as part of their censorship. There are two possibilities: a network admin in Pakistan messed up and accidentally implemented their censorship in a way that affected the whole world, or this was done maliciously. If the latter is the case, well, the Pakistanis may soon be discovering that they need the Internet more than the Internet needs them.
Update 2: As of around 16:00 EST, YouTube is back up and working. Either PCCW filtered the bad route or the Pakistanis stopped sending it. And do check out Greg’s comments below; he’s the networking expert.
Update 3 (Feb 25): Here’s the best technical synopsis of what happened to YouTube yet.
Update 4: This animated visualization provides the clearest view of the hijacking yet. Watch all of the routes divert to Pakistan Telecom within a matter of minutes, and then two hours later, revert just as quickly back to YouTube.
Update 5: Hey look, MSNBC has picked up the story! I wouldn’t have guessed that this would make mainstream media. Or that they would get the technical details right. But it looks like they talked to the knowledgeable folks at Renesys, who I linked to in Update 3.