We continue to monitor the effect of the filtering of large ntp packets (> 128 bytes) at the Janet borders. Where people have had concerns we've been working with them to make sure that their work is impacted as little as possible by this measure.
The filtering has had a large reduction on the impact to Janet infrastructure but the current filtering limits still allow enough traffic through the Janet border to cause disruption for customers with 100Mb/s, or busy 1Gb/s, connections.
The increasing frequency, number and size of ntp based DDoS attacks against Janet connected organisations has at times briefly degraded connectivity to sections of the network. Whilst we are able to react to these attacks as and when they occur, the impact upon our customers can be significant. This situation is far from unique to Janet - ISPs globally are struggling with this issue.