Microsoft Knowledge Base Article 914841 contains the following introduction:
This article describes an update that you can apply to simplify the creation and maintenance of Internet Protocol security (IPsec) filters in a Microsoft Windows Server 2003-based environment.
This update adds functionality to Windows that enables you to use an IPsec "Simple Policy." For most environments, the installation of this update lets you reduce the number of IPsec filters that are required for a Server Isolation deployment or for a Domain Isolation deployment. You can reduce the number of IPsec filters from many hundreds of filters to only two filters.