diff --git a/troubleshooting.rst b/troubleshooting.rst
index 39c047d..6c0d74e 100644
--- a/troubleshooting.rst
+++ b/troubleshooting.rst
@@ -1,2 +1,70 @@
 Troubleshooting Guide
 =====================
+
+Frequently Used Commands
+------------------------
+In this section, we are going to introduce a few commands we frequently used when troubleshooting SD-Fabric.
+
+ONOS
+^^^^
+To execute following ONOS CLI commands,
+
+- Create K8s port forwarding by `kubectl -n tost port-forward onos-tost-onos-classic-0 8101`
+- Login to ONOS CLI by `ssh -p 8101 karaf@localhost`. Default password is `karaf`
+
+ONOS basics
+"""""""""""
+- `flows`: List flow tables. `-s` for simplified output.
+- `groups`: List group tables. `-s` for simplified output.
+- `devices`: List device information. `-s` for simplified output.
+- `ports`: List port information. `-e` to list enabled ports only.
+- `links`: List discovered links
+- `hosts`: List discovered hosts. `-s` for simplified output.
+- `netcfg`: List network configuration
+- `interfaces`: List interface configuration
+
+trellis-control
+"""""""""""""""
+- `sr-pr-list`: List current recovery phase of each device
+- `sr-device-subnets`: List device-subnet mapping
+
+fabric-tna
+""""""""""
+- `slices`: List network slices
+- `tcs`: List traffic classes of given slice
+
+up4
+"""
+- `read-interfaces`: List all interfaces installed in the data plane
+- `read-pdrs`: List all PDRs installed in the data plane
+- `read-fars`: List all FARS installed in the data plane
+- `read-flows`: List all UE data flows installed in the data plane)
+
+Stratum
+^^^^^^^
+To execute following BF SDE commands,
+
+- Login to Stratum switch by `ssh root@<switch_ip>`. Default password is `onl`
+- Attach to Stratum docker container by `docker attach \`docker ps | grep stratum-bfrt | awk \'{print $1}\'\``
+
+  - Hit `enter` for the prompt
+  - Use `<Ctrl-P><Ctrl-Q>` to exit the container. Do not use `<Ctrl-C>` since it will terminate the process.
+
+BF SDE
+""""""
+- `pm.show`: List port configurations. `-a` to list all ports.
+
+K8s troubleshooting
+-------------------
+..
+    TODO Hung-Wei
+
+onos-diagnostics
+----------------
+..
+    TODO Hung-Wei
+
+FAQ
+---
+..
+    TODO Hung-Wei