> IIRC, the ISP published bogus routes, and the cooperating providers > accepted the BGP-pushed routes for some strange reason.
A very simple and stupid reason. Several transit providers ignore long standing best practices, and don't filter route announcements. And at least one of them (PCCW) was upstream of Pakistani telecom. And so they leaked out those announcements. And a bunch of other providers picked up those routes from PCCW, still believing them. There's a lot of very well developed routing best practices (just walk into any nanog, ripe, apricot etc meeting for discussions, tutorials etc on these, or troll through google). Pity is that some providers are just too dumb to follow these.
