We have identified an issue with some of our network switches and so are in the process of deploying fixes to these and as part of the process upgrading firmware on them. This will result in a brief interruption to transit whilst the switches are restarted to load the new firmware. This should not cause any more than 1-2mins outage per switch (if your services are connected to or linked to the affected switches).
We apologise for any inconvenience caused whilst we proactively address this issue.