Abstract: A data distribution system comprises a plurality of processing devices (8) connected by a packet-based transport network (2), and a session manager (12). The session manager (12) is configured to manage a distribution session by (i) associating two or more of the processing devices (8) with a multicast group on the transport network, (ii) storing and/or accessing a mapping between a session identifier for the distribution session and the multicast group address, and (iii) configuring the transport network (2) and/or the processing devices (8) so that data output to the multicast group by any one of the processing devices in the group is received by all the other processing devices in the group. Each of the processing devices (8) can receive data from a respective node (16) located on an external network, and send the received data, or data derived therefrom, over the transport network (2) to a multicast group.

Abstract: A relay system has a router and multiple relay servers with specific network addresses on a first network. The router and servers are mutually connected by a second network. The router receives a relay-service request from a source on the first network, addressed to an address distinct from the relay servers' specific addresses. It forwards the request to the relay servers. Each relay server instructs the source to issue a relay-service request to its specific address. The server that receives the request provides the service. Two routers may be connected to different respective sub-networks of the first network and be connected to each other by the second network. The routers announce a common destination network address on the first network. The first network is configured such that only one of the routers receives a data packet addressed to the common address, which it forwards onto the second network.

Abstract: A data distribution system comprises a plurality of processing devices (8) connected by a packet-based transport network (2), and a session manager (12). The session manager (12) is configured to manage a distribution session by (i) associating two or more of the processing devices (8) with a multicast group on the transport network, (ii) storing and/or accessing a mapping between a session identifier for the distribution session and the multicast group address, and (iii) configuring the transport network (2) and/or the processing devices (8) so that data output to the multicast group by any one of the processing devices in the group is received by all the other processing devices in the group. Each of the processing devices (8) can receive data from a respective node (16) located on an external network, and send the received data, or data derived therefrom, over the transport network (2) to a multicast group.

Abstract: In the field of IP telephony, a video conference call is established between a calling node and a called node. Identification information relating to a calling party is transmitted to a connection server, which accesses a database of information relating to one or more parties and links between the parties. It uses the links to determine a set of parties depending on the identity of the calling party. It transmits identification information relating to the set of parties, and receives a selection from a user of a party from said set. It interrogates a database to determine a network address for one of the nodes and initiates a call with one of the nodes. It sends a call-transfer instruction to that node, which instructs the node to cease the call with the connection server and to transfer the call to the other node.

Abstract: A relay system has a router and multiple relay servers with specific network addresses on a first network. The router and servers are mutually connected by a second network. The router receives a relay-service request from a source on the first network, addressed to an address distinct from the relay servers' specific addresses. It forwards the request to the relay servers. Each relay server instructs the source to issue a relay-service request to its specific address. The server that receives the request provides the service. Two routers may be connected to different respective sub-networks of the first network and be connected to each other by the second network. The routers announce a common destination network address on the first network. The first network is configured such that only one of the routers receives a data packet addressed to the common address, which it forwards onto the second network.