alt Hacker News>We were building 40 Gbps packet sniffers at Google (4x 10 Gbps NICs) and needed switches that could do things like mirror traffic across ports at line rate
I'm sure there were good reaasons for this, but man this just sounds bad. Like that's the spec I think NSA must give to their contractors outfitting 611 Folsom Street's Room 641A
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It does sound bad the way OP described it, but packet or HTTP mirroring is a standard feature of A/B testing and blue-green deployments of a very critical code. Mirror traffic between version 1 and 2, then compare response body, response time and return response A to the end users.
Nah, packet mirroring is a standard networking feature and ideally every feature is line rate.
There are companies that mirror their traffic to storage for a few days to be able to look back and troubleshoot issues. ALL their traffic, proactively.
Port mirroring is the network engineer's equivalent of using breakpoints in a debugger for a programmer. It allows you to inspect what happens on the wire to get a clue for what's wrong.