At around 21:50 we were alerted to an outage in our core network.
Engineers immediately investigated and ascertained it was a brief outage of the forwarding engine of our core switching fabric.
This caused our network to stop passing traffic for around a minute, unfortunately this was just enough time to cause the network to re-converge and meant that parts of the network were un-accessible from parts of the outside world for around 20 mins.
We will further investigate the cause of this original outage and update once we know more.