Even though the present form of IPv6 has been existing since 1998, the adoption of the new protocol has been very slow until recently. To help the adoption of the IPv6 protocol, several transition technologies were introduced. The 6to4 protocol is one of them, and it can be used when an IPv6 enabled host resides in an IPv4 only environment and needs to communicate with other hosts in such circumstances or with native IPv6 hosts. Five open source 6to4 relay implementations were investigated: Debian Linux - sit, Debian Linux - v4tunnel, OpenWrt - sit, FreeBSD - stf, NetBSD - stf. The measurement method is fully described including our measurement scripts and the results of the measurements are disclosed in detail. The measurements have shown that there are major differences between the different types of implementations.

During the IPv6 deployment there is a frequently occurring situation where two IPv6 enabled hosts need to communicate with each other over a network that supports only IPv4. Application of the 6to4 IPv6 transition method can solve this problem. The performance and stability of the different 6to4 relay implementations is a very important subject. We measured the performance and tested the stability of three open source 6to4 relay implementations under Debian Linux, OpenBSD and OpenWRT platforms. We present and discuss our results, analyze the stability of the 6to4 relay implementations and compare their performance metrics. Our measurements methods may be useful for other researchers, and our results may help the system architects to choose the appropriate solution.