I can explain why modern data centers need micro-segmentation in two words: Trojan Horse. Not the malware, but that timeless story of wooden-horsey riding saboteurs. In it, we see that even the most powerful perimeters fall short. The bad guys always find a way in. With virtualized data centers and desktops, this notion is particularly troubling. What if someone breaches the firewall protecting your virtual environments? Once inside, malware and attackers freely move laterally (east-west) causing mayhem and tons of financial damage.