Intermittent packet loss.
Our report from the incident is as follows.
Minor intermittent packet loss, causing some packets to be dropped. This had negligible effect on servers at Joule House, the effects may not have even been noticeable to end users.
The intermittent packet loss duration was 2 minutes.
The load on a core router suddenly increased with no known cause.
Our external monitoring probes immediately reported the fault. End users may not have noticed the issue as it had near negligible effect on overall service.
As the router was non-responsive to input, it was deemed necessary to restart the device. Seamless failover completed to the other router whilst the device was powered down. There was no loss of service during failover.
The router was powered back on, underwent a consistency check and was added back into the routing pool.