To identify performance changes due to VPP code development between previous
and current VPP release version, both have been tested in CSIT environment of
latest version and compared against each other. All substantial progressions and
regressions have been marked up with RCA analysis. See
:ref:`vpp_throughput_comparisons` and :ref:`vpp_known_issues`.

Physical Testbeds
-----------------

FD.io CSIT performance tests are executed in physical testbeds hosted by
:abbr:`LF (Linux Foundation)` for FD.io project. Two physical testbed
topology types are used:

- **3-Node Topology**: Consisting of two servers acting as SUTs
  (Systems Under Test) and one server as TG (Traffic Generator), all
  connected in ring topology.
- **2-Node Topology**: Consisting of one server acting as SUTs and one
  server as TG both connected in ring topology.

Tested SUT servers are based on a range of processors including Intel
Intel Xeon Skylake-SP, Intel Xeon Cascade Lake-SP, Arm,
Intel Atom. More detailed description is provided in
:ref:`tested_physical_topologies`. Tested logical topologies are
described in :ref:`tested_logical_topologies`.

Server Specifications
---------------------

Complete technical specifications of compute servers used in CSIT
physical testbeds are maintained in FD.io CSIT repository:
`FD.io CSIT testbeds - Xeon Cascade Lake`_,
`FD.io CSIT testbeds - Xeon Skylake, Arm, Atom`_.