A method implemented at a first network node, comprising: receiving a report of clock quality of a second network node from a third network node, wherein a clock of the first network node is selected as a master clock for synchronization in a first timing domain, a clock of the second network node is selected as a master clock for synchronization in a second timing domain, and the third network node is attached to at least the first timing domain and the second timing domain; determining whether to synchronize the first timing domain to the second timing domain, based at least in part on the received report; obtaining timing information of the second network node from the third network node, in response to the determination of synchronizing the first timing domain to the second timing domain; and tuning the clock of the first network node to synchronize the first timing domain to the second timing domain, based at least in part on the timing information of the second network node, wherein tuning the clock of the first network node to synchronize the first timing domain to the second timing domain comprises: generating timing information of the first network node based at least in part on the timing information of the second network node; and distributing the timing information of the first network node to one or more other network nodes within the first timing domain, wherein the one or more other network nodes within the first timing domain comprise at least the third network node. receiving a report of clock quality of a second network node from a third network node, wherein a clock of the first network node is selected as a master clock for synchronization in a first timing domain, a clock of the second network node is selected as a master clock for synchronization in a second timing domain, and the third network node is attached to at least the first timing domain and the second timing domain; determining whether to synchronize the first timing domain to the second timing domain, based at least in part on the received report; obtaining timing information of the second network node from the third network node, in response to the determination of synchronizing the first timing domain to the second timing domain; and tuning the clock of the first network node to synchronize the first timing domain to the second timing domain, based at least in part on the timing information of the second network node, wherein tuning the clock of the first network node to synchronize the first timing domain to the second timing domain comprises: generating timing information of the first network node based at least in part on the timing information of the second network node; and distributing the timing information of the first network node to one or more other network nodes within the first timing domain, wherein the one or more other network nodes within the first timing domain comprise at least the third network node. generating timing information of the first network node based at least in part on the timing information of the second network node; and distributing the timing information of the first network node to one or more other network nodes within the first timing domain, wherein the one or more other network nodes within the first timing domain comprise at least the third network node. <EOS>