Fosdem 2015: a status update

As is our tradition by now a team of volunteers helped out with the network setup and operation of Free and Open-source Software Developers’ European Meeting (FOSDEM). The network was very similar to the one used last year and we wanted to report on the evolution of the traffic we measured.

First the bad news: due to the increased use of IPv6 we have less accurate data. This is because while IPv4 uses a unique MAC address which we can use to count the number of clients, IPv6 uses ephemeral addresses, and one physical device can use multiple global IPv6 addresses. In fact we noticed one client using more than 100 global IPv6 addresses over a period of 240 seconds. Why this client is doing this is a mystery.

The unique link local IPv6 addresses were only kept in the neighbour cache of the router for a limited time, so we have no good numbers for the amount of clients. The good news is we can still use traffic counters to compare with the previous year.

Internet traffic evolution

Compared to 2014 we saw a 20% increase in traffic to more than 2 terabytes of traffic exchanged with the internet.

Fosdem 2015 wireless traffic distribution

More interestingly the IPv4 traffic on the wireless network decreased by almost 20% with the net result that now the IPv6 traffic is 60% of the traffic on the wireless network, while IPv4 traffic is only 40%. So IPv6 traffic is 1.5 times the IPv4 traffic. This is a good indicator that most clients now can use NAT64 and can live on a IPv6 only network.

Internet IPv4 versus IPv6 for Fosdem 2014-2015

On the internet side the IPv4 traffic increased by 5% while the IPv6 traffic almost doubled. As we use NAT64 to give access to IPv4 only hosts using IPv6 only on the internal network this measurement is a clear indication that more content is now available via IPv6.

For next year we plan to setup some more tracking systems in advance so we can investigate the number of clients on the wireless network and why some clients are using hundreds of global IPv6 addresses.