A method performed by a VLAN manager for managing an allocation of a VLAN (VLAN1, VLAN2) for a deployment between a first virtual machine and a second virtual machine for transferring data packets wherein a virtual machine (410, 420) is attached to a host (430, 440), the method comprising the steps of: - receiving a request for allocating a VLAN (VLAN1, VLAN2) being identified by a virtual VLAN identifier (VLAN 100), - identifying a free physical VLAN identifier (VLAN300) • by checking an assignment of a virtual VLAN identifier (VLAN 100) of the requested VLAN (VLAN1, VLAN2) to a physical VLAN identifier (VLAN200) wherein the physical VLAN identifier (VLAN200) is to be used uniquely by a VLAN switch device (450, 460) for switching data packets ef over the requested VLAN (VLAN1, VLAN2) and • by performing, in case the physical VLAN identifier (VLAN200) is in use, a procedure for determining at least one free physical VLAN identifier (VLAN300) wherein the determination procedure comprises checking for a physical VLAN identifier (VLAN200) that each VLAN switch device (450, 460) on the path between the first virtual machine and the second virtual machine transferring data over the requested VLAN (VLAN1, VLAN2) does not already use the same physical VLAN identifier (VLAN200) for routing data packets, - assigning the virtual VLAN identifier (VLAN100) to the determined at least one free VLAN physical identifier (VLAN300) for the requested VLAN (VLAN1, VLAN2), - instructing each VLAN switch device (450, 460) involved in the communication over the requested VLAN (VLAN1, VLAN2) to apply the assignment between the virtual and the physical VLAN identifier (VLAN 100, VLAN300) to the data packets transferred by the VLAN switch device (450, 460) for the requested VLAN (VLAN1, VLAN2) by replacing the virtual by the physical VLAN identifier (VLAN100, VLAN300) or vice versa according to the assignment. - receiving a request for allocating a VLAN (VLAN1, VLAN2) being identified by a virtual VLAN identifier (VLAN 100), - identifying a free physical VLAN identifier (VLAN300) • by checking an assignment of a virtual VLAN identifier (VLAN 100) of the requested VLAN (VLAN1, VLAN2) to a physical VLAN identifier (VLAN200) wherein the physical VLAN identifier (VLAN200) is to be used uniquely by a VLAN switch device (450, 460) for switching data packets ef over the requested VLAN (VLAN1, VLAN2) and • by performing, in case the physical VLAN identifier (VLAN200) is in use, a procedure for determining at least one free physical VLAN identifier (VLAN300) wherein the determination procedure comprises checking for a physical VLAN identifier (VLAN200) that each VLAN switch device (450, 460) on the path between the first virtual machine and the second virtual machine transferring data over the requested VLAN (VLAN1, VLAN2) does not already use the same physical VLAN identifier (VLAN200) for routing data packets, • by checking an assignment of a virtual VLAN identifier (VLAN 100) of the requested VLAN (VLAN1, VLAN2) to a physical VLAN identifier (VLAN200) wherein the physical VLAN identifier (VLAN200) is to be used uniquely by a VLAN switch device (450, 460) for switching data packets ef over the requested VLAN (VLAN1, VLAN2) and • by performing, in case the physical VLAN identifier (VLAN200) is in use, a procedure for determining at least one free physical VLAN identifier (VLAN300) wherein the determination procedure comprises checking for a physical VLAN identifier (VLAN200) that each VLAN switch device (450, 460) on the path between the first virtual machine and the second virtual machine transferring data over the requested VLAN (VLAN1, VLAN2) does not already use the same physical VLAN identifier (VLAN200) for routing data packets, - assigning the virtual VLAN identifier (VLAN100) to the determined at least one free VLAN physical identifier (VLAN300) for the requested VLAN (VLAN1, VLAN2), - instructing each VLAN switch device (450, 460) involved in the communication over the requested VLAN (VLAN1, VLAN2) to apply the assignment between the virtual and the physical VLAN identifier (VLAN 100, VLAN300) to the data packets transferred by the VLAN switch device (450, 460) for the requested VLAN (VLAN1, VLAN2) by replacing the virtual by the physical VLAN identifier (VLAN100, VLAN300) or vice versa according to the assignment.