Brno University of Technology (BUT) is one of the biggest universities in the Czech Republic. The core of the network is fully dual-stacked and IPv6 is deployed on several faculties as well.  We are using IPv6 Provider Independent prefix to be able to use multihomed IPv6 connections. The university campus network connects more than 2,500 staff users and more than 23 000 students.

IPv4 and IPv6 traffic on the university’s upstream lines


IPv6 traffic and flows ratios – all networks

This graph shows the ratio between IPv4 and IPv6 traffic on university’s upstream lines. All BUT networks are taken into consideration.
The numbers are computed as follows

  • IPv6 traffic ratio = IPv6 traffic / (IPv4 traffic + IPv6 traffic) * 100
  • IPv6 flow ratio = IPv6 flows / (IPv4 flows + IPv6 flows) * 100

IPv6 traffic and flows ratios – dual-stacked networks only

This graph shows the ratio between IPv4 and IPv6 traffic only for dual-stacked networks. The numbers are computed same as in previous graph.


IPv6 host penetration

This graph shows the ratio between unique MAC addresses in ARP and NC (Neighbor cache). Only dual-stacked network are taken into consideration. If the percentage is above 100% it means, that there are more hosts in NC than in ARP cache. The main reason for this is that a cache timeouts for ARP and NC are different.
The number is computed as follows:

  • seen unique MAC in NC  / seen unique MAC in ARP cache * 100

Tomas PodermanskiIPv6 @ Brno University of Technology