A method for transmitting data packets of a data traffic between a sending device (10, 80) and a receiving device (80, 10) via a VPN client and a VPN server over a network using a secure encapsulation of the data packets, the method comprising the steps of: - determining a Quality of Service, QoS, parameter for the data packets of said data traffic, - selecting, for the data packets, either a first tunnel connecting the VPN client and the VPN server or a second tunnel connecting the VPN client and the VPN server based on determined Quality of Service, wherein the selection of the first or second tunnel is carried out in a traffic mapping unit (300, 600) which transmits the information about the selected first or second tunnel to the VPN client or VPN server, wherein the data packets are sent to a first IP address at a first virtual interface at the VPN client or to a second IP address of a second virtual interface at the VPN client in dependence on the determined QoS parameter, one IP address being associated with each of the tunnels, wherein the data traffic contains a source and a destination, IP address, wherein, when the QoS parameter is determined the source IP address is translated to either the first IP address or the second IP address in dependence on the determined QoS parameter when the data packets are sent to the VPN server. - determining a Quality of Service, QoS, parameter for the data packets of said data traffic, - selecting, for the data packets, either a first tunnel connecting the VPN client and the VPN server or a second tunnel connecting the VPN client and the VPN server based on determined Quality of Service, wherein the selection of the first or second tunnel is carried out in a traffic mapping unit (300, 600) which transmits the information about the selected first or second tunnel to the VPN client or VPN server, wherein the data packets are sent to a first IP address at a first virtual interface at the VPN client or to a second IP address of a second virtual interface at the VPN client in dependence on the determined QoS parameter, one IP address being associated with each of the tunnels, wherein the data traffic contains a source and a destination, IP address, wherein, when the QoS parameter is determined the source IP address is translated to either the first IP address or the second IP address in dependence on the determined QoS parameter when the data packets are sent to the VPN server. wherein the selection of the first or second tunnel is carried out in a traffic mapping unit (300, 600) which transmits the information about the selected first or second tunnel to the VPN client or VPN server, wherein the data packets are sent to a first IP address at a first virtual interface at the VPN client or to a second IP address of a second virtual interface at the VPN client in dependence on the determined QoS parameter, one IP address being associated with each of the tunnels, wherein the data traffic contains a source and a destination, IP address, wherein, when the QoS parameter is determined the source IP address is translated to either the first IP address or the second IP address in dependence on the determined QoS parameter when the data packets are sent to the VPN server.