Both companies have also released APIs to integrate AV, patch management, personal firewall, and other security software into their schemes. Third-party vendors have responded with enthusiasm: Symantec, McAfee, and Trend Micro are participating in both Cisco and Microsoft's programs, and dozens of other players have signed on with one or both initiatives.
NAC and NAP operate on the same principle: An agent on the host queries other software such as AV, patch management, or a personal firewall for health and security status. Then the agent communicates that information to a policy server, which compares the host's current status to a predefined policy.
While the principles are the same, the execution differs. NAC puts enforcement power in the hands of network hardware, while Microsoft relies on a DHCP server running Windows software