OVH Network Outage 18/07/2013

Tonight, OVH disappeared from the internet. From around 01:16 AM till 01:26 AM, none of OVH’s entire network could be reached. With a reported 150,000 servers in the EU and 360,000 servers in Northern America, OVH is one of the largest providers in the world. Not being able to access any of their leased services means that a lot of connectivity is lost…

So what could have happened? OVH Network Status page states that 3 Route Reflectors have reloaded (read: restarted) after an issue with their OSPF routing processes caused a crash. We can find out which systems these were by finding an OVH IP that is not responding and cross referencing it with a resource such as So, we have the Autonomous System Number  (ASN) of the devices under OVH’s control, we can now see how much of the internet they own… shows us the networks allocated to this system in slash notation format. To put this into perspective, there are 10 /16 subnets alone in the allocated prefixes list… That’s 655360 IP addresses which make up 40% (as a quick estimate) of the OVH Network…

Here’s what happened as shown in BGPlay:

I’m still looking into this as it’s just occurred and I need sleep :P Will post updates soon.

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