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Next generation (NG) routers, characterized by high speed interfaces, large switching capacity and petabit packet processing speed have recently been deployed in core networks of world class operators. Based on distributed architectures, these routers are designed with control cards and line cards interconnected by a very high-speed switch fabric, where line cards contain processing and memory resource allowing the sharing of some route processing tasks with control cards. The traditional implementation model of router software, where control cards assume all the processing tasks, is therefore no longer appropriate. In this paper, we propose a distributed model for implementing router software in order to fully exploit the hardware platform of the next router generation, taking into account the additional capacity of line cards. The model corresponds to a distributed architecture with control cards acting as super nodes and line cards acting as peers. It also provides "direct" communication between line cards, allowing them to cooperate in some task processing without going through control cards. Such a model significantly increases the robustness, scalability and availability of routers. We also investigate the proposed distributed model in the context of different protocols supported by a router, such as signaling and routing protocols. Two case studies are presented where we discuss the advantages of the distributed model for OSPF and LDP protocols.