A method of announcing a description of a media session, for example a multimedia conference, that is to take place over multicast capable links is provided in networks configured for Internet Protocol operation. A modular method of announcing media sessions includes: (a) generating a first base module having a first data structure having user oriented data relevant to the media session; (b) generating at least one media module having a second data structure with media oriented data necessary for a user to receive a respective media stream of the media session; (c) providing a link between the first base module and the at least one media module; and, (d) announcing the media session by making at least the first base module available to potential recipients of the media session.