The invention provides an optical network system (1001) which consists of a plurality of optical cross-connection units. The optical cross-connection units are provided with optical path establishing devices (1316), a plurality of optical edge routers (1003) and switching units. An external IP network (1002) is connected with an optical network (1001) by the optical edge routers (1003). The switching units take optical path as the unit so as to utilize the optical path to connect the optical edge routers (1003). In the construction of the optical network system (1001), the optical edge routercomprises: (1) an optical network control instance INSp which keeps topology information in the optical network (1001) and performs optical path routing and signaling; (2) an IP network instance INSiwhich keeps an external IP network routing table and operates a routing protocol between the edge routers and the external IP network. Thereby, a multi-layer linkage function can be realized, and theoptical network with a high stability can be improve.