With the rapid development of Internet, traditional centralized routers can not meet the requirements of next generation Internet on reliability, performance scalability and service scalability. Cluster routers will be the most important components of future Internet. It is very important for cluster routers to maintain the same forwarding table images among cluster router nodes. Different synchronization mechanisms have variant performance to control plane and packet forwarding plane. After the analysis of two typical synchronization mechanisms, this paper proposes an asymmetrical forwarding table synchronization framework — AREF (asymmetrical routes electing framework) synchronization framework. It fits the requirements of massively parallel cluster routers architecture perfectly. Continuous route flapping of the backbone network burdens the synchronization mechanisms of cluster routers. AREF synchronization algorithm is proposed to decrease the synchronization costs of AREF synchronization framework during route flapping. It uses route cache to predict a new best route when the original best route is deleted, and reduces the synchronization cost of AREF synchronization framework greatly. AREF synchronization framework and algorithm requires diverse abilities for different routing node types and can be used in heterogeneous cluster router widely.