Tracing:
Windows Communication Foundation (WCF) uses the tracing mechanism defined in the System.Diagnostics namespace. In this tracing model, trace data is produced by trace sources that applications implement. Each source is identified by a name. Trace consumers create trace listeners for the trace sources for which they want to retrieve information. To receive trace data, you must create a listener for the trace source.
Activity Tracing and Propagation:
Having ActivityTracing enabled and propagateActivity set to true in the system.ServiceModel trace sources for both the client and service provide correlation of traces within logical units of processing (activities), across activities within endpoints (through activity transfers), and across activities spanning multiple endpoints (through activity ID propagation).
These three mechanisms (activities, transfers, and propagation) can help you locate the root cause of an error more quickly using the Service Trace Viewer tool. For more information, see Using Service Trace Viewer for Viewing Correlated Traces and Troubleshooting.
The following link describe in details:
How to enable tracing and message logging