Abstract: A virtual local area network 2 provides a multicasting facility between a first termination point 1 and a plurality of other termination points 3, 4, wherein a source identifier associated with the first termination point 1 is advertised over the network with an indication that it relates to the multicast, and the other termination points 3, 4 select transmissions associated with the said source identifiers to be advertised to the other termination points such that the other termination points 3, 4 can identify and select data transmissions relating to the multicast. The data may also be transmitted by way of another network 9 as a backup, the termination points 3, 4 preferentially selecting data transmissions from the virtual local area network 2 by identification of a weighting applied to those transmissions sent via the VLAN.

Abstract: A virtual private data network is overlain on an internet connection to allow prioritisation of connection between two or more specified terminations over a switched network, thereby minimising latency in the system. Data to be transmitted between the specified terminations is identified by a weighting prefix and its routing is prioritised over other data for the same destination termination.

Abstract: A virtual private data network is overlain on an internet connection to allow prioritisation of connection between two or more specified terminations over a switched network, thereby minimising latency in the system. Data to be transmitted between the specified terminations is identified by a weighting prefix and its routing is prioritised over other data for the same destination termination.

Abstract: A virtual local area network 2 provides a multicasting facility between a first termination point 1 and a plurality of other termination points 3, 4, wherein a source identifier associated with the first termination point 1 is advertised over the network with an indication that it relates to the multicast, and the other termination points 3, 4 select transmissions associated with the said source identifiers to be advertised to the other termination points such that the other termination points 3, 4 can identify and select data transmissions relating to the multicast. The data may also be transmitted by way of another network 9 as a backup, the termination points 3, 4 preferentially selecting data transmissions from the virtual local area network 2 by identification of a weighting applied to those transmissions sent via the VLAN.