As the signal speeds get faster, it is too risky to leave testing to lab. Current technologies such as DDRs, signal processors and fast serial data techniques (USB, 10Base-T, Thunderbolt etc.) are real challenges.
Not that it is difficult to make valid measurements with prototypes, it is virtually impossible to make changes. And the semiconductor properties may change from one lot to the next. So it is important to find out how much margin the design has to avoid problems in later stage.
Hyperlynx is the leading brand in signal integrity and recommended by several semiconductor (and FPGA) vendors. There are different levels of Hyperlynx available, depending on application technology.
ModelSim and Questa are the leading brands to introduce advanced verification tools. Mixed signal support is often required to allow the usage of IP blocks. See below for more information.