The invention relates to a time triggered network used in particular in an automotive network having a plurality of clusters. Each cluster (A-X) includes a plurality of nodes (11). For saving time during startup a cluster coupler unit (10) in a time triggered network is proposed, wherein the network comprises a plurality of communication clusters (A-X) each having a plurality of nodes (11), the communication clusters (A-X) are compatible to each another in cycle length, slot length and frame length, wherein a cluster coupler unit (10) being connected to at least two communication clusters (A-X), the cluster coupler unit (10) includes as many protocol engines (12) as communication clusters are connected, each protocol engine (12) having at least one receiving input (RXD) and one transmitting output (TXD), wherein a synchronization logic (20) is connected to at least one of the receiving inputs (RXD) and/or the transmitting outputs (TXD) of the protocol engines (12), wherein the synchronization logic (20) distributes information from incoming/outgoing signals, which is used for synchronizing the connected communication clusters (A-X) during startup.