SafeGuard: Safe forwarding during route changes
This paper presents the design and evaluation of SafeGuard, an intra-domain routing system that can safely forward packets to their destinations even when routes are changing. SafeGuard is based on the simple idea that packets carry a destination address plus a local estimate of the remaining path cost. We show that this simple design enables routers to detect path inconsistencies during route changes and resolve on a working path for anticipated failure and restoration scenarios. This in turn means that route changes do not disrupt connectivity although routing tables are inconsistent over the network. We evaluate the router performance of SafeGuard using a prototype based on NetFPGA and Quagga. We show that SafeGuard is amenable to high-speed hardware implementation with low overhead. We evaluate the network performance of SafeGuard via simulation. The results show that SafeGuard converges faster than a state-of-the-art IP fast restoration mechanism and reduces periods of disruption to a minimal duration, i.e., the failure detection time. Copyright 2009 ACM.