This paper describes a negotiation protocol proposed for inter-agent cooperation in a multi-agent system that we developed for optimisation and dynamic integrated scheduling within steel production. The negotiation protocol is a two-level bidding mechanism based on the Contract Net Protocol. The purpose of this protocol is to allow the agents to cooperate and coordinate their local schedules in order to find globally near-optimal robust schedules, whilst minimising the disruption caused by the occurrence of unexpected real-time events. We conduct several experiments to investigate the performance of this negotiation protocol to coordinate the agents in generating good quality robust schedules. This performance is evaluated in terms of stability and utility measures used to evaluate the robustness of the steel production processes in the presence of real-time events.