2.1 Overview

WSUS is composed of two protocols:

  • Windows Update Services: Client-Server Protocol, as specified in [MS-WUSP]. This protocol enables update-client-to-update-server communication. Its purpose is to transfer update metadata, deployments, and content from an update server to an update client, and to report status information from an update client to an update server. These operations might rely on the update server that has acquired update metadata, deployments, and content from another update server by using the Windows Update Services: Server-Server Protocol.

  • Windows Update Services: Server-Server Protocol, as specified in [MS-WSUSSS]. This protocol enables server-to-update-server communication. Its purpose is to transfer update metadata, deployments, and content from an upstream server (USS) to a downstream server (DSS), and to send aggregated status information from a DSS to a USS. These operations might rely on the DSS that has acquired status information from update clients by using the Windows Update Services: Client-Server Protocol.