A method of promoting a quick data flow of groups of data packets in a network, said network comprising a plurality of network domains (100, 200, 300), each network domain comprising a plurality of network elements (S1.1, S1.2, S1.3, S1.4, S1.5, S1.6; S2.1, S2.2, S2.3, S2.4, S2.5, S2.6; S3.1, S3.2, S3.3, S3.4, S3.5, S3.6) of a first class each serving as a switch and at least one network element (10, 20, 30) of a second class different from the first class each serving as a controller, said switches (S1.1, S1.2, S1.3, S1.4, S1.5, S1.6; S2.1, S2.2, S2.3, S2.4, S2.5, S2.6; S3.1, S3.2, S3.3, S3.4, S3.5, S3.6) adapted to receive data packets and to forward the same to a respective neighbour switch which is determined by exclusively using entries in a flow information database stemming from a controller and stored in the forwarding switch and said controllers (10, 20, 30) adapted to create such a flow information database and to forward the same to at least one switch (S1.1, S1.2, S1.3, S1.4, S1.5, S1.6; S2.1, S2.2, S2.3, S2.4, S2.5, S2.6; S3.1, S3.2, S3.3, S3.4, S3.5, S3.6), said method comprising: - receiving a first data packet of a group of data packets by a switch (S1.1) in a first network domain - extracting, by the first switch (S1.1), address information from the first data packet specifying to which network element of the network the data packet is to be sent, - if to the address information, no entry in a flow information database exists, forwarding the first data packet from the switch to a first controller of the first network domain, - extracting, by the first controller, the address information from the data packet, - determining, by the first controller, by using the address information a path (S1.1, S1.3, S1.5, S1.6; S1.1, S1.4, S1.5, S1.6;) of connected switches in the first network domain to be travelled through by the group of data packets as well as a switch (S 3.6) in a second network domain to which the data packets are to be sent from a switch (S1.6) in the first network domain, - determining at least a second controller (30, 40) outside of the first network domain which might or will, according to a first predetermined criterion, be involved with further forwarding of the group of data packets at a later stage, - forwarding (S28, S30) alerting data to the second controller (30, 40), said alerting data being data providing the address information or information derived therefrom, wherein the first controller sends the alerting data to a controller of the second network domain as the second controller, thereby enabling the second controller (30, 40) to perform process steps prior to arrival of the first data packet at the second network domain, wherein said second controller (20,30) of the second network domain determines, upon receipt of the alerting data, from the alerting data a path of connected switches in its domain to be travelled through by the group of data packets, creates at least an entry in a flow information database on the basis of the determined path and sends it to at least some of those of the switches (S3.6, S3.5, S3.4, S3.2) which are part of the path. - receiving a first data packet of a group of data packets by a switch (S1.1) in a first network domain - extracting, by the first switch (S1.1), address information from the first data packet specifying to which network element of the network the data packet is to be sent, - if to the address information, no entry in a flow information database exists, forwarding the first data packet from the switch to a first controller of the first network domain, - extracting, by the first controller, the address information from the data packet, - determining, by the first controller, by using the address information a path (S1.1, S1.3, S1.5, S1.6; S1.1, S1.4, S1.5, S1.6;) of connected switches in the first network domain to be travelled through by the group of data packets as well as a switch (S 3.6) in a second network domain to which the data packets are to be sent from a switch (S1.6) in the first network domain, - determining at least a second controller (30, 40) outside of the first network domain which might or will, according to a first predetermined criterion, be involved with further forwarding of the group of data packets at a later stage, - forwarding (S28, S30) alerting data to the second controller (30, 40), said alerting data being data providing the address information or information derived therefrom, wherein the first controller sends the alerting data to a controller of the second network domain as the second controller,