Cisco Systems and Microsoft are headed for a collision over network security, with customers caught in the middle.< . . .
Cisco Systems and Microsoft are headed for a collision over network security, with customers caught in the middle.

The two companies have each proposed competing "end to end" security architectures, marking the latest evolution in network defense--an approach concerned not only with scanning for viruses but also with policing networks to deny connections to machines that don't conform with security policies. But for now at least the twin offerings are not interoperable. That means customers might be forced to choose between using technology from one company or the other, unless the two tech giants can strike a deal to guarantee compatibility.

Choosing could be tough, given that both companies thoroughly dominate their respective markets: Microsoft has a monopoly in desktop operating systems, and Cisco's share of the corporate network routing market exceeds 70 percent.

Microsoft and Cisco say they are working to ensure interoperability. But at this stage, it's difficult to know how quickly the two sides will come together and what the resulting security plan will look like--or if it's even feasible to bridge the gap between their technologies at all.