Performance Evaluation of TI-LFA in Traffic-Engineered Segment Routing-Based Networks

Link failures have a significant negative impact on the availability of a network and should therefore be resolved as soon as possible. Because of the slow convergence time of routing protocols upon detection of a link failure, several IP Fast ReRoute (FRR) mechanisms have been developed to overcome this problem. Recently, segment routing, which is a flexible and scalable way of doing source routing, enabled a new FRR mechanism called Topology Independent Loop-Free Alternate (TI-LFA). As the name suggests, the key feature of TI-LFA is that it guarantees a loop-free detour against any link failure in any network topology. However, typically fast responses to failures only aim to restore the loop-free connection between the affected routers and do not consider the resulting delay or impact on network congestion. This paper presents an initial study on the selected TI-LFA backup paths and their effect on the overall network performance. By means of simulation, we evaluate how efficient TI-LFA reroutes traffic for a number of traffic engineering approaches. Our results quantify the impact of different traffic engineering approaches and network loads on the performance of TI-LFA. This suggests potential directions for improving the effectiveness of TI-LFA protection in segment routing.