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round trip. one way 5 to 7 micros. some special cards go down to 3 one way, however with rtt, software usually adds some 2 micros overall

Less than 1us, RTT to software (http://exablaze.com/exanic-x4)

Less than 400ns per switch hop (http://www.arista.com/en/products/7150-series) excluding congestion.