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Fosdem 2015: a status update

- March 3, 2015 - 7 Comments

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

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

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

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.


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    More details please ... on packets v. bytes, in v. out. The "Fosdem 2015 wireless traffic distribution" pie chart. Is this packets or bytes? "Internet IPv4 versus IPv6 for Fosdem 2014-2015" bar chart. Shows packets. How about bytes? How about Internet traffic IN IPv4 versus IN IPv6 bytes?

  1. From my reading of the not very precise graph, about 32% of the external traffic was IPv6. This includes the traffic from the v6 only network not going through NAT64 + the v6 traffic from dual stack network. Can we have the amount of v6 from the dual stack network (which will 100% go out as v6) to substract it on both sides and get the % of traffic from the v6 only network going out as v6/going through the NAT64?

      Unfortunately both the native IPv6 and the dual stack network were sharing the same access-lists, so we do not have the raw numbers to work on.

      • About 32% of the external traffic was IPv6 which I believe means that between 32% and 53% of the traffic was available over v6. If people on dual stack network were not using any v6, 60% of traffic would come from the v6 only network, it would mean 53% was available over v6 (32% of external out of 60% of internal). If ratio was the same on both networks (i.e. all devices on the dualstack were connected over v6 for anything available on v6) it would mean only 32% was available over v6.

  2. Also, I hate pie charts. There is (almost) never a good reason to use a pie chart. A stacked bar chart would be just as good, with IPv4 and IPv6 in 2 separate bars. And the colors. #fb290f (orange-red) is IPv4 in one chart and IPv6 in the other, this is confusing. I would suggest using one color group for IPv4 and different shades of that color for the protocols inside it (light blue to dark blue), and another color group for IPv6 (light orange to brown) And totally different colors in the first chart, because traffic direction is definitely not the same as protocol! I hope you can do something with this constructive criticism. A reading suggestion: The Visual Display of Quantitative Information, by Edward Tufte. :)

  3. What is a terrabyte? I only know of terabytes or tebibytes. Terra = Latin, meaning "earth" Tera = Greek, meaning "monster". Equals (10^3)^4 Tebi = binary prefix based on tera. Equals (2^10)^4 I'd at expect that Cisco network engineers get their units right! ;-)

      Fixed the typo, thanks for mentioning it.