A method for assisting in synchronization of slave clocks in a communication network comprises receiving, in a node of the communication network, a message comprising a value of a synchronization accuracy (σrec) of a first upstream node in the communication network. A value of an accuracy (σlink) of a link latency unbalance between forward and reverse signalling in a link on which the node received the message is obtained. A value of a total synchronization accuracy (σtot) of the node comprises at least the accuracy (σlink) of the link latency unbalance of the link on which the node received the message is calculated. A node for assisting in synchronization of slave clocks in a communication network is also presented.