Software-based fast failure recovery in load balanced SDN-based datacenter networks
In an OpenFlow network, the controller is responsible to control and manage the whole network. Although such central control paradigm is easier to achieve efficient network resources usage, the controller becomes the bottleneck when the network size is large. In this paper, we propose using pre-provisioned paths to mitigate the burden on a controller. The basic idea is to setup some background paths in the network. When an ordinary flow coming into the network, the controller only needs to setups flow entries at the ingress and egress switches. An admitted flow follows a preplanned path toward its destination. Except the ingress and egress switches, the flow entries in the remaining switches on the path kept unchanged. Since routing paths for ordinary flows are pre-planned, the whole admission and connection setup process are simplified. Jointly considering load balancing, network survivability, fast failure recovery, and flow entry consumption are the major challenges in this problem. The contribution of this paper includes two parts. First, we propose a path preplanning scheme that takes advantage of interface specific forwarding (ISF) to resolve the problem. We formulate the path preplanning problem as an integer linear programming problem. Optimization based heuristic algorithms are proposed to obtain a near optimal solution. In the second contribution, we propose a software based failure detection and failure location identification scheme. Since some existing switches take longer time to detect a network failure, a reliable lightweight software based failure detection scheme that can fast pinpoint the failure location is needed. We have performed simulations and experiments to evaluate the performance of the proposed schemes. The experimental results indicate that the proposed software failure detection scheme generates very limited overhead on the OpenFlow controller. It can be used to achieve fast failure recovery even when the network is in heavy load state. The simulation results also show that the proposed ISF based path preplanning scheme can reduce controller load and is able to achieve 100% survivability against any single link failure with low bandwidth consumption.