Cisco says it will have its Microsoft-compatible NAC gear ready in about a month, which should be good news for a lot of potential NAC users who are customers of both vendors.

Cisco NAC being compatible with Microsoft network access protection (NAP) means users can deploy NAC without having to also deploy a NAC client.   Instead, endpoints using Microsoft Vista can use the built-in NAP client.

This seemed to be of particular interest to a group of about 250 attendees at RSA Conference 2008 last week in San Francisco. More than half raised their hands when asked if they were customers of both Microsoft and Cisco and interested in deploying NAC using both companies’ products. Some of them said they had actually waited for this compatibility before they started seriously considering NAC.

This seems to be a power of Microsoft and Cisco. They’ve both been talking about NAC for longer than most other companies, providing roadmaps and, in the case of Cisco, a progression of NAC products. Such is their sway that promises of eventual products can freeze a large number of their existing customers from making commitments to new technologies until these heavy-hitters weigh in.

If compatible NAC/NAP products do become available soon, it will mark a new phase in NAC’s lifecycle. Microsoft and Cisco will likely grab a big chunk of the customers because they already have their feet in the doors of a vast number of business customers.

It will mean that startup NAC vendors will have to step up their games and stay ahead of these two in the features they offer.

Tim Greene is senior editor at Network World.