update reeadme

README.md

@@ -16,3 +16,30 @@ To understand  The software-defined networking well, I trying to create a simple
 - [awesome-sdn](https://github.com/sdnds-tw/awesome-sdn)
 - [ryu](https://github.com/faucetsdn/ryu)
 - [learn-sdn-with-ryu](https://github.com/knetsolutions/learn-sdn-with-ryu)
+
+## Plan
+
+```mermaid
+stateDiagram
+con: Controller
+conf: Controller frame
+ofp: Openflow Manager
+ofph: Openflow Header
+ofpe: Openflow Event Message
+ofpv10_h: openflow v1.0 header
+ofpv10_e: openflow v1.0 Event
+
+ofpv13_h: openflow v1.3 header
+ofpv13_e: openflow v1.3 Event
+
+[*] --> con
+con --> conf
+conf --> ofp
+ofp --> ofph
+ofph --> ofpv10_h
+ofph --> ofpv13_h
+
+ofp --> ofpe
+ofpe --> ofpv10_e
+ofpe --> ofpv13_e
+```