Avoiding Forwarding Loop Across Multiple Domains Without Controller Synchronization in SDN

Software-defined networking (SDN) is an emerging architecture that enables network management by decoupling network control plane and data plane forwarding functions. The network controller not only monitors the data traffic but also defines the forwarding rules. Broadcast limit and loop avoidance are essential requirements for OpenFlow devices. The multiple domains are necessary for scalability in large-scale networks like on wide area network (WAN), metropolitan area networks etc. On the data plane layer, one inter-domain link connection among multiple domains in the SDN limits the scalability of SDN networks. Thus, at least two inter-domain connections are required to improve the scalability of end-to-end services in the whole SDN network. However, the two links cause loops and packet drop problems in the SDN network without controller synchronization. In this paper, the Avoid Loop with Test Packet (ALTP) scheme solution is used to provide end-to-end delivery service of data traffic and to avoid the above issues (i.e., forwarding loop and packets drop) without synchronization of control planes between the different domain controllers. The test packets in the ALTP scheme is echo and reply packets, we are used this mechanism to check the path's delay rate by using inter-domain links from the source node to the destination node. In the ALTP scheme, the source domain controller keeps the one link active among multiple inter-domain links through its egress nodes.