Firstly. the proactive policy to ALM tree which is based on Chord DHT was extended and a back-path scheme with which each node pre-calculates a backup path for itself was proposed. When the non-leaf node leaves. all its child nodes can switch to the respective backup path immediately. https://www.roneverhart.com/MagnaFlow-2003-2006-Toyota-Corolla-Street-Series-Cat-Back-Performance-Exhaust-System/