Design and Implementation of High Availability OSPF Router *

In this paper, we propose a High Availability Open Shortest Path First (HA-OSPF) router which consists of two OSPF router modules, active and standby, to support a high availability network. First, we used the continuous-time Markov chain (CTMC) to analyze the steady-state availability of an HA-OSPF router with one active router and N standby routers (1 + N redundancy model). Then, with the failure detection and recovery rate considered, from analytic results, we show that the HA-OSPF router with 1 + 1 redundancy model, one active and one standby, is the preferred model for enhancing router availability. We also show that the carrier-grade HA-OSPF router availability (i.e., five-nine availability) can be achieved under an appropriate combination of the router module failure rate (λ), repair rate (μ), and the failure detection and recovery rate (δ). Since there is a lack of research on the integration of the redundancy model, link state information backup, and failure detection and recovery, we propose a high availability management middleware (HAM middleware) framework to integrate these three elements. The HAM middleware consists of Availability Management Framework (AMF) service, Checkpoint service, and Failure Manager. It supports health check, state information exchange, and failure detectio