The difference between these two categories of metrics is actually quite useful!
- Metrics from the TESS agent show performance as measured from the TIM / MTP (where the packet collection occurs via SPAN/Tap). This includes round trip time across the network between your collection point and your application server.
- Metrics from the Introscope agent show performance as measured from the JVM/CLR itself. This does not include any network round trip time. The Introscope agent re-uses the CEM definitions to analyze the handled HTTP requests and present the performance under the Business Segment node.
This means, when you see a large difference between the CEM / TESS metrics and the Introscope Agent metrics, you are seeing the performance impact of the network (switches, routers, etc.) and other infrastructure (web server, virtual switches, etc.). If the TESS metrics are indicating a very slow transaction, but the Introscope agent metrics are not (for that same Business Transaction / Business Segment definition), then the performance problem is due to environment, not the application itself.
The Application Triage Map attempts to bring both categories together in one view to help perform this comparison.