According to some sources including the Software Improvement Group Trend Report on IPv4 Captivity 2011 much software, currently in both production and development, contains IPv4-specific code and will fail when IPv6 is deployed. Now might be a good time to check your test strategies in this regard.
SIG used “lightweight” static analysis, looking for literals used with socket libraries, hardcoded IP addresses and so on, in their research. The fact the approach found them proves its worth, but many defects it cannot detect certainly exist. Deeper static analysis can detect more, but empirical testing is needed too.
For IPv6-only testing, that means setting up an IPv6 test environment with all IPv4 addressing and routing disabled. Easy enough, but the trouble is most applications will be running over “dual-stack” (IPv4-mapped IPv6 addresses) or “tunnelling” (one protocol’s packets encapsulated within packets of the other) networks for some time to come, so it may not be realistic. Building and testing either of these interim arrangements as a test environment is challenging.
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