There is described a system for authenticating a client device in a network having a plurality of IDM components. One or more of the IDM components subscribes (using the publish-subscribe message pattern) to authentication requests published by client devices. The client device publishes an authentication request into the network. The most appropriate IDM component to process the published authentication request is selected, and the authentication request forwarded to the selected IDM component. The selected IDM component is then operated to negotiate with and authenticate the client device.