A method including: identifying a set of dependent virtualised network functions included in a first virtual network, the set including at least a virtualised network function to be updated; creating a second virtual network including clones of virtual machines implementing the dependent virtualised network functions of the set; interconnecting, in the second virtual network, clones of the dependent virtualised network functions, identically to an interconnection in the first network of dependent virtualised network functions; identifying an input data packet of the dependent virtualised network functions, duplicating the packet and sending the duplicated packet to the second network; applying a patch to the clone of the virtualised network function to be updated in the second network; triggering an alert when a performance value of a dependent virtualised network function of the first virtual network differs from a performance value on the clone of the virtualised network function in the second network.