Inspecting the quality of individual IP blocks is one thing, but it's even more important to assess your vendor and their design processes. One of the simplest and most effective steps that you can take is to examine their test plans. You should be able to trace from the industry specification, through the functional specification, to the test plan for each and every item in the industry specification.
This means that the test plan will be a significant document. For example, the Synopsys DesignWare PCI Express test plan is a 101 page document that details each element of the plan to verify the VIP against the industry specification. In addition to directed testing, constrained random testing is critical to generating enough interface traffic to ensure coverage as well as finding deep, dark corner case conditions that nearly impossible to conceive and are therefore not explicit in the test plan.
Finally, designers need to ensure that their VIP vendor can support them at the critical time they need it, like tape-out. This means that the vendor must have the extensive, expert resources necessary to handle this support, as well as a proven track record of delivering it.
There's no question that designers are requiring increasing amounts of Verification IP and that this trend is only expected to continue. However, if designers don't take it upon themselves to examine their VIP vendor as seriously as they do their silicon IP or design tools, the VIP they acquire may end up hurting them more than it helps.
Ed Bard is director of marketing for DesignWare IP libraries at Synopsys.