diff --git a/configuration.rst b/configuration.rst
index 7870475..6119f31 100644
--- a/configuration.rst
+++ b/configuration.rst
@@ -1,6 +1,24 @@
 Configuration Guide
 ===================
 
+There are several different types of configuration we use in SD-Fabric.
+We will explain every configuration in this section.
+
+Control plane configurations,
+including configuration for ONOS and SD-Fabric applications (``SegmentRouting``, ``UP4``, ``INT``)
+can be categorized as **network configuration** (sometimes shortened as ``netcfg``) and **component configuration**.
+
+  - **Network configurations** are network-related attributes,
+    including device, subnet, VLAN, routes...etc.
+  - **Component conofigurations** are application component attributes,
+    including feature flags, polling intervals, timeouts...etc.
+
+Data plane configurations, including port speed, breakout channel and queue configurations
+are done in Stratum **chassis config**.
+
+We have implemented config pusher in both ONOS and Stratum helm chart,
+fetching and applying configurations automatically once the system is ready.
+
 .. toctree::
    :maxdepth: 2
    :glob:
diff --git a/images/test-overview.png b/images/test-overview.png
new file mode 100644
index 0000000..6863974
--- /dev/null
+++ b/images/test-overview.png
Binary files differ
diff --git a/testing.rst b/testing.rst
index e8830bf..70ba36d 100644
--- a/testing.rst
+++ b/testing.rst
@@ -1,11 +1,34 @@
 Testing Guide
 =============
 
+Test Infrastructure Overview
+----------------------------
+
+We implemented multiple types of tests in SD-Fabric.
+
+- **Unit Test**
+
+  - Verify codes at the level of methods or classes, and therefore covers a lot of details in a small scope.
+  - Run before merge as part of the CI/CD process of each component.
+
+- **Component Test**
+
+  - Verify a component with its dependencies as a whole.
+  - Run as sanity checks before merge as part of the CI/CD process of each component.
+
+- **System Integration Test**
+
+  - Verify the entire SD-Fabric solution,
+    involving multiple components and including various failure scenarios.
+  - Run nightly
+
+.. image:: images/test-overview.png
+  :width: 800px
 
 .. toctree::
    :maxdepth: 2
    :glob:
 
-   testing/system
    testing/component
    testing/pipeline
+   testing/system