Late last night and earlier this afternoon there have been some intermittent faults with connectivity, mostly affecting users connecting to the internet through the Servology network using VPN tunnels, but also occasionally affecting colocated servers. I have discovered that some traffic was still passing through the backup router whose hard disk became faulty earlier this year. I don’t believe today’s problems are due to the faulty hard disk, but more likely a bug in the (very old) BGP implementation on that router, which was causing it to emit bad announcements under certain circumstances, causing other routers to drop and reestablish their BGP sessions with it. However, I believe I have mitigated the problem by adjusting some routing metrics to better ensure traffic is diverted away from the backup router whenever possible. I will now be treating the project to replace this router as very urgent.