Starting from yesterday afternoon, the IP-Plus network (AS3303) has suffered from severe difficulties, and initially even outages. Starting from the afternoon, IP-Plus started pushing an enormous amount of prefixes out to all peers.
For most routers, pushing an enormous amount of routes causes an emergency shutdown of the corresponding peering, and that was what IP-Plus must have experienced a lot that evening. (At least it happened on all routers I have access to, and I heard reports from others indicating the same.)
IP-Plus has a trouble ticket suggesting that a DDoS attack was the direct cause of the outages. However, no DDoS attack could ever have caused the effects we were seeing, so it appears that IP-Plus is trying to disguise human error as a force they are unable to control. This is not appropriate.