Lots of Tools, Lots of Choices
As a quick look at the Wikipedia article "Comparison of packet analyzers" will attest, many more protocol analysis tools exist than do certifications to support them. As of this writing, the table lists 26 tools, but only 14 of those are free and widely available to the general population. The granddaddy of them all, the venerable tcpdump, is still being maintained, and remains widely used worldwide. Six commercial products are listed, including some of the underlying NetScout products that support the nGenius certifications.
Outside the three toolsets that support protocol analysis certifications, lots of options are available for interested IT professionals to consider or try. Most of the commercial products (at least those that remain commercially available today) are also subjects for professional training coursesmostly in the classroom, but some in online or self-paced forms as well. You can look for books on some of these tools, both free and commercial, and find a surprising number of offerings available in the aftermarket as well.