This draft proposed vertical layered communication method; especially it is mechanism to notify locator changing from L3Shim to TCP layer. In this draft, it is called indirect TCP congestion control. This mechanism make TCP congestion situation using behavior of L3Shim layer without correcting conventional TCP. And then we describe L3Shim state through the event. These kinds of events and progress state are presented in a single system view. And it will be help to implement L3Shim functionality through understanding L3Shim process.