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Several real-time applications (e.g., video conferencing, remote control systems) demand guarantees on message delivery latency. Supporting such QoS constrained connections requires the existence of a routing mechanism which computes paths that satisfy QoS constraints. In a mobile ad hoc network, wireless links tend to fail frequently as nodes move in and out of transmission range of one another. Providing fault tolerance with QoS guarantees in such networks is challenging. An algorithm called segmented backup source routing (SBSR) provides fault tolerance with end-to-end delay as the QoS parameter. The algorithm constructs a set of delay-constrained segmented backup paths. Each such segmented backup path protects a segment of the primary path rather than the entire path. This approach has two advantages. First, one is able to identify backup paths for any selected primary path, as long as there exists a pair of node disjoint paths from source to destination (in other words, if there are two node disjoint paths, it is not required to use either of them as the primary path). This has the advantage that the primary path may be selected based on QoS considerations rather than a consideration of fault tolerance. The second significant advantage is that the connection reliability of the segmented backup path set is higher than the two disjoint paths. We design a framework to analyse the connection reliability of such a segmented backup path set.