A backhaul domain of the communication network is determined 400, and a request for a synchronization reference is received 402 from the first access node, the request comprising, ID:s of the first and second access nodes. For each one of the first and second access nodes, a first and a second combination are determined 404 of a first and a second respective synchronization reference and related synchronization paths extending between synchronization reference nodes of the synchronization references and the access nodes. For each one of the first and second access nodes, the first or the second combination of synchronization reference and related synchronization path is selected 406 based on synchronization requirements for the first and second access nodes, and the first path or the second path is requested to be set-up 408 according to the selected 406 combination.By providing functionality which works on the top of existing control of radio and transport domains, appropriate synchronization references may be determined with a limited amount of information exchanged between the respective domains.