According to the exponential growth of services available on large distributed networks, transport customers require relevant, interactive and instantaneous information during their travels. Thus, we designed and implemented a multi-agent information system using a special kind of software agents: the Mobile Agents. However, some network errors can occur during the mobile agents moving through the distant network nodes (bottleneck, failure, crash...). For this problem, we define in this paper a mobile agent negotiation process to reassign required services to available network nodes according to their current states in their correspondent final routes called Workplans. Furthermore, the complex interactions features of our system exceed the limits of the traditional negotiation systems which impose several restrictions on the type and format of the negotiation messages. Therefore, we designed and implemented a flexible transport ontology which allows an easy handling of the terms and messages for negotiating.