A method performed by a proxy device interconnecting at least a first and a second communications network (101, 102), communication devices (111, 112, 113, 121, 122, 123) connected to either said communications network (101, 102) transmitting advertisement messages, each including a piece of information about the communication device (111, 112, 113, 121, 122, 123) having transmitted the advertisement message, the piece of information relating to parameters of said communication device (111, 112, 113, 121, 122, 123) and/or functionalities implemented by said communication devices (111, 112, 113, 121, 122, 123) and/or services implemented by said communication device (111, 112, 113, 121, 122, 123), wherein said proxy device performs: - collecting the pieces of information included in advertisement messages received by the proxy device from communication devices (111, 112, 113, 121, 122, 123) connected to either said communications network (101, 102); - storing said collected pieces of information in a caching unit; and, upon receiving a query about parameters of communication devices (111, 112, 113, 121, 122, 123) and/or functionalities implemented by communication devices (111, 112, 113, 121, 122, 123) and/or services implemented by communication devices (111, 112, 113, 121, 122, 123), the proxy device further performs: - retrieving, from the caching unit, pieces of information corresponding to the received query; - generating a response message including the retrieved pieces of information; and - transmitting, in response to the received query, the generated response message wherein, when the retrieved pieces of information comprise pieces of information about several communication devices (111, 112, 113, 121, 122, 123), the response message aggregates said retrieved pieces of information into the response message, characterized in that, when retrieving the pieces of information corresponding to the received query from the caching unit, the proxy device performs: - filtering the pieces of information stored by the caching unit, by removing the pieces of information about communication devices (111, 112, 113, 121, 122, 123) connected to respective communication networks (101, 102) for which the proxy device has no authority for responding on behalf of communication devices (111, 112, 113, 121, 122, 123) connected thereto; and - forwarding the received query via each communications network (101, 102) for which the proxy device has no authority for responding on behalf of communication devices (111, 112, 113, 121, 122, 123) connected thereto, except, when the received query is received in multicast form, the communications network (101, 102) from which said query has been received by the proxy device. - collecting the pieces of information included in advertisement messages received by the proxy device from communication devices (111, 112, 113, 121, 122, 123) connected to either said communications network (101, 102); - storing said collected pieces of information in a caching unit; - retrieving, from the caching unit, pieces of information corresponding to the received query; - generating a response message including the retrieved pieces of information; and - transmitting, in response to the received query, the generated response message wherein, when the retrieved pieces of information comprise pieces of information about several communication devices (111, 112, 113, 121, 122, 123), the response message aggregates said retrieved pieces of information into the response message, - filtering the pieces of information stored by the caching unit, by removing the pieces of information about communication devices (111, 112, 113, 121, 122, 123) connected to respective communication networks (101, 102) for which the proxy device has no authority for responding on behalf of communication devices (111, 112, 113, 121, 122, 123) connected thereto; and - forwarding the received query via each communications network (101, 102) for which the proxy device has no authority for responding on behalf of communication devices (111, 112, 113, 121, 122, 123) connected thereto, except, when the received query is received in multicast form, the communications network (101, 102) from which said query has been received by the proxy device.