Following some recent reports of very low packet loss on some routes via Cogent, we performed extensive testing of our core infrastructure and located a potential issue with one leg of our metropolitan core ring. (Our core ring traverses four buildings, utilising a different supplier for each leg of the ring to ensure the most resilience)
This leg of the ring was provided by VirginMedia Fibre, so we raised a query with them to look into it further.
VirginMedia attended their core site in Manchester at 3pm today to diagnose the issue. The engineer replaced the SFP module (fibre termination module) at the VM end of the link in Manchester, and cleaned the fibre ends as a courtesy to ensure good light levels.
Further Netnorth testing shows the low packet loss has now disappeared along this link and the circuit is operating normally. We have re-integrated the circuit back into the ring and full resilience has been restored.
Connectivity was uninterrupted due to our ring formation network which automatically re-routed the affected traffic via the opposite leg of the ring. This happens almost instantly.