Level3 Transit Failure

At 11:55pm tonight, our connection to Level3 appeared to disconnect.  The symptoms are identical to the previous occasions where the Level3 router rebooted so we assume this to be the case again tonight.

The connection is slowly coming back online, which further supports this suspicion.

As Level3 appear to be unconcerned by a router that reboots itself, we have already made plans to migrate to an alternative transit supplier.  This is due to take place early February 2017.

Once this replacement is online, we will likely retire our Level3 connectivity entirely.

Some routes may have experienced a brief period of packet loss or increased latency during this transit fault whilst routers around the internet changed paths to our alternate transit links.  The majority of destinations would have been entirely unaffected however.

As this is caused by routers outside of our control, we have no way to prevent this brief packet loss to some destinations.

Any paths via our peering links or other transit connectivity are unaffected.

Network Connectivity

We’re seeing packet loss on the LINX Extreme network this morning.
We’ve also got alerts coming in for our London location too, this is routed entirely separately to our Bolton/Manchester locations, so it looks like it is affecting the entire LINX LAN.

We’ve shunted most traffic over to the LINX Juniper network so this should die down now. We’ve not had any official word from LINX yet, however we will continue to monitor and migrate traffic paths where possible.

Netnorth Support

Storms / Power – Bolton

There is currently a storm over the Bolton area (with very nice fork lightning!) which has caused a brief power outage this evening around 7pm UK local time.

Our UPS units continued to operate during the outage with no loss of power to the datacentres, and our generators started to take over the load if required.

This was not required as the mains was restored within a few seconds.

Our generators returned to their idle state after a few minutes once mains power stability was confirmed.


Should there be any further outages, the generators will re-start automatically.  The process to transfer power to generator in a mains fail situation is fully automated.

LINX Extreme LAN – IGMP issue

Yesterday, at around 11:50am, we had some reports of unusual activity on our ring network.

We traced this down to elevated levels of CPU usage on our switches.  Further investigation pointed to a high level of IGMP traffic being received.

We further traced this to our LINX Extreme peering port in London and shut the port down.  This resolved the issue instantly.

We contacted our Connexions provider, who provide our LINX ports.  They did investigation to ensure the traffic was not originating internally and then passed the query onto LINX.

LINX confirmed this morning that they had a member port injecting IGMP traffic to the peering LAN yesterday and that this has now been resolved.


We have re-enabled our LINX Extreme port and confirmed the issue no longer exists.

We will re-enable our peering connections via this LAN shortly.

Cisco switch stack issue (DS-101)

Earlier this evening we identified one of our Cisco switch stacks misbehaving causing a constant stream of stack reconverges – this constant reconverge event has been causing layer 2 network instability for traffic flowing via the stack of nine switches.

We have just completed a physical inspection of all stack cables, including full reseating of cables as per Cisco’s guidelines – however the problem still persists.

It is possible that the stack issues are caused via a software fault within the Cisco IOS software.

We are currently applying an upgrade to the switch stack and will reboot the full stack afterwards to activate the changes.

Cisco advise doing this as a full cold reboot by removing the power from the stack members so this reload will take longer than usual.


Any customers connected to a different switch stack will only see a momentary outage during a layer 2 reconvergence.

Customers directly connected to switch stack DS-101 will see a total outage for up to 15 minutes.