Network virtualization has been propounded as a diversifying attribute of the future inter-networking paradigm. However, monitoring and troubleshooting operational virtual networks can be a daunting task, due to their size, distributed state, and additional complexity introduced by network virtualization. We propose an analytics approach for the analysis of network traces collected across hypervisors and switches. To re-organize individual trace events into path-wise slices that represent the life-cycle of individual packets, we first present a trace slicing scheme. Then, we develop a path characterization scheme to extract feature matrices from those trace slices. Using those feature metrics, we develop a set of trace analysis algorithms to cluster, rank, query, and verify packet traces. We have developed the analytics approach in a SDN network management tool, and presented evaluation results to show how it can enable visibility and effective problem diagnosis in a SDN network.