Abstract: A method (500), a system and a gateway (400) for communicating between hosts in private networks having IPv4 address spaces are disclosed. One or more DNS query messages for resolving resource records are transmitted (502) from a first private network for a remote host in a second private network. One or more DNS replies comprising a private IPv4 address for the remote host are received (504). If the one or more DNS replies comprise a synthesized IPv6 address, the IPv6 address is extracted from the replies and a peer IPv4 address in the first network is allocated for the remote host (508). The IPv6 address comprises a global IPv6 prefix and the private IPv4 address for the remote host. The peer IPv4 address is associated with an extracted IPv6 address for the remote host. The remote host is addressed using the IPv6 address for transmission of IPv4 packets from the first network addressed using the peer IPv4 address (510).

Abstract: A network (100) of machines and method (200) for allocating a unique subnet identifier to a subnet in the network (100) having multiple subnets (155,160,165,170,175,190) and a plurality of associated routers (110, 130, 140, 150, 105). The unique subnet identifier provides part of an address of the subnet that is coupled to a router interface and is allocated by firstly determining that a subnet identifier for one of said subnets (155,160,165,170,175,190) is required. A step of allocating automatically a unique subnet identifier to the router interface is then effected, wherein the unique subnet identifier is determined to be unique by said network. A configuring step then configures the subnet to be addressed by said network 100 by using an address based at least partially on said unique subnet identifier.

Abstract: A method (500), a system and a gateway (400) for communicating between hosts in private networks having IPv4 address spaces are disclosed. One or more DNS query messages for resolving resource records are transmitted (502) from a first private network for a remote host in a second private network. One or more DNS replies comprising a private IPv4 address for the remote host are received (504). If the one or more DNS replies comprise a synthesized IPv6 address, the IPv6 address is extracted from the replies and a peer IPv4 address in the first network is allocated for the remote host (508). The IPv6 address comprises a global IPv6 prefix and the private IPv4 address for the remote host. The peer IPv4 address is associated with an extracted IPv6 address for the remote host. The remote host is addressed using the IPv6 address for transmission of IPv4 packets from the first network addressed using the peer IPv4 address (510).

Abstract: A method (200) and machine for validating that an identifier is unique within an ad-hoc network (100) of machines. The method comprises obtaining the identifier (220) and then sending a claim request for the identifier to machines in the network (100). Thereafter a step validating the identifier as unique is effected only if an invalidation message is not received within a predefined time period. The invalidation message is indicative of the identifier already being allocated to one of the machines in the network (100).

Abstract: A network (100) of machines and method (200) for allocating a unique subnet identifier to a subnet in the network (100) having multiple subnets (155,160,165,170,175,190) and a plurality of associated routers (110, 130, 140, 150, 105). The unique subnet identifier provides part of an address of the subnet that is coupled to a router interface and is allocated by firstly determining that a subnet identifier for one of said subnets (155,160,165,170,175,190) is required. A step of allocating automatically a unique subnet identifier to the router interface is then effected, wherein the unique subnet identifier is determined to be unique by said network. A configuring step then configures the subnet to be addressed by said network 100 by using an address based at least partially on said unique subnet identifier.