We have received the official reason for outage from Level3 Communications for the brief 5 minute outage on our Level3 IP connectivity yesterday (12th September 2012) shortly after midnight.
The outage was caused by routine maintenance by Level3 who had failed to notify us in advance. This has been resolved for future to ensure that we receive advanced warning of maintenance works.
Level3 Communications provide our primary IP connectivity path. During the 5 minute outage, our secondary path automatically took over.