Ensuring that IP Security (IPSec) gateway meets its performance expectations is one of the most important objectives that IPSec gateway development team must face with. Only suitable validation approach may prove that IPSec gateway throughput is correct, Security Associationspsila adding/removing time is acceptable, IPSec gateway is capable of processing huge number of flows and IPSec rekeying works with required performance level. This paper puts forward a plan for IPSec gateway performance testing. Discussion is illustrated with several examples of test cases that can be used during IPv4/IPv6 IPSec gateway validation and verification.