OpenVZ® is a virtualization software from a company called Virtuozzo. It is popular with hosting companies (because it is cheap), and it gives the ability to sell VPS. Typically an offer will include a limit on the bandwidth (for example: “1TB/month traffic”).
However there is a little dirty secret that most hosting companies do not know: in 97% of the node configurations, the IPv6 traffic is unaccounted for! Thus the VPS has an unlimited bandwidth allowance when sending or receiving traffic when using IPv6.
Enjoy unlimited IPv6 traffic today!