The need to monitor real time network services has prompted service providers to use new measurement technologies, such as service-specific probes. A service-specific probe is an active probe that closely mimics the service traffic so that it receives the same treatment from the network as the actual service traffic. Service-specific probes are end-to-end and their deployment depends on solutions that address questions such as minimizing probe traffic, while still obtaining maximum coverage of all the links in the network. A polynomial-time probe-path computation algorithm is provided as well as a 2-approximate solution for merging probe paths when the number of probes exceeds a required bound k. The algorithms are evaluated using ISP topologies generated via Rocketfuel. For most topologies, it is possible to cover more than about 98% of the edges using just about 5% of the nodes as terminals.