Analysis of existing IP Fast Reroute mechanisms

After a link or router failure within a network, a process of network convergence starts. During this process, the network is experiencing serious connectivity issues, in which different destinations may become unreachable and which may cause difficulties for critical and sensitive services. In order to address these issues, IP Fast ReRoute (IPFRR) mechanisms have been developed. The main goal of all IPFRR mechanisms is to minimize the network recovery time after a link or router failure. Using the IPFRR mechanisms, the network recovery time during a link or router failure takes only a few milliseconds. In this paper, we focus on the analysis of existing IPFRR mechanisms. We describe the main problematic areas of existing IPFRR mechanisms. Several IPFRR mechanisms have already been proposed. The key feature of these mechanisms is the calculation of an alternative route before the failure occurs. The computation of alternative route requires network topology information and therefore most of the existing IPFRR mechanisms strongly depend on the usage of distance-vector or link-state routing protocols. Our research shows, that pre-computing and dependence on routing protocols are primary problematic areas, which limit usage of existing IPFRR mechanisms in IP networks.