+ +--------+ +-------+ +--------+
+ | | | | | |
+ | Trex | ---> | VNF | ---> | Trex |
+ | | | | | |
+ +--------+ +-------+ +--------+
+
+Supported testcases scenarios:
+
+* Correlated UDP traffic using TREX traffic generator and replay VNF.
+
+ * using different IMIX configuration like pure voice, pure video traffic etc
+ * using different number IP flows e.g. 1, 1K, 16K, 64K, 256K, 1M flows
+ * Using different number of rules configured e.g. 1, 1K, 10K rules
+
+For UDP correlated traffic following Key Performance Indicators are collected
+for every combination of test case parameters:
+
+* RFC2544 throughput for various loss rate defined (1% is a default)
+
+KPI Collection
+^^^^^^^^^^^^^^
+
+KPI collection is the process of sampling KPIs at multiple intervals to allow
+for investigation into anomalies during runtime. Some KPI intervals are
+adjustable. KPIs are collected from traffic generators and NFVI for the SUT.
+There is already some reporting in NSB available, but NSB collects all KPIs for
+analytics to process.
+
+Below is an example list of basic KPIs:
+* Throughput
+* Latency
+* Packet delay variation
+* Maximum establishment rate
+* Maximum tear-down rate
+* Maximum simultaneous number of sessions
+
+Of course, there can be many other KPIs that will be relevant for a specific
+NFVI, but in most cases these KPIs are enough to give you a basic picture of
+the SUT. NSB also uses :term:`collectd` in order to collect the KPIs. Currently
+the following collectd plug-ins are enabled for NSB testcases:
+
+* Libvirt
+* Interface stats
+* OvS events
+* vSwitch stats
+* Huge Pages
+* RAM
+* CPU usage
+* IntelĀ® PMU
+* Intel(r) RDT