Impact of IPsec and 6to4 on VoIP quality over IPv6

We conduct experiments in a LAN environment to determine the impact of IPsec and 6to4 encapsulation on VoIP quality in future IPv6 networks. We measure VoIP performance in the presence of varying background traffic for each of four IPsec scenarios with IPv6 and 6to4 encapsulation, with and without NAT, and compare with IPv4. The scenarios reflect situations commonly encountered in today´s VPNs including no-security (i.e., traffic bypasses IPsec), network-to-network (i.e., an IPsec VPN between corporate sites), client-to-network (i.e., remote user access to a corporate network via IPsec tunnels), and client-to-client (i.e., IPsec transport mode for secure end-to-end communication). We use the popular Openswan implementation of IPsec and focus on ESP with the authentication option. The measures used for evaluating VoIP performance are delta (packet inter-arrival time), jitter, packet loss, throughput, and MOS. Our results demonstrate that VoIP quality due to using IPsec with IPv6, 6to4, and NAT in VPNs during the IPv4/IPv6 transition is not significantly different from using IPsec with IPv4, and that there is a minimal impact on voice quality as long as the network capacity is not exceeded.