NTT Corporation NTT Corporation GMPLS protocol enabled network operator to setup optical path network rapidly and dynamically. Recently, WSON [8] is standardized to achieve WDM core network. However, it is difficult that all network equipment supports WSON protocol. Therefore, interoperability between WSON and non-WSON nodes is needed to construct path network. This document describes requirement for interoperability between WSON node and non-WSON nodes and functions that routing and signaling protocol should support.