Method of exchanging information between two networks operating under different routing protocols

A method of exchanging information between a first network and a second network, each made up of network elements, comprising:

• connecting the first and second networks, which are different from each other, the first network being a secure avionics network and the second network being a public network, which together form an on-board network for an aircraft, to each other via at least two first routing elements that are selectively associated with the first network, and by at least one second routing element that is associated with the second network and that is connected to the first routing elements;
• the first network implementing a routing protocol using static routing tables;
• the second network implementing a routing protocol using dynamic routing tables and including a stage of exchanging identification messages each having a neighborhood identification field normally dedicated to receiving the identifiers of neighboring network elements directly connected to the network element issuing the identification message and informing the neighboring network elements that the issuing network element is active, and a stage of exchanging routing table update messages, which update messages normally contain the identifiers of network elements to which the message-issuing network element knows it is connected either directly or indirectly;
• each first routing element issuing to the second routing element identification messages each having a neighborhood identification field containing the identifiers of network elements to which the first routing element knows it is connected directly or indirectly;
• in each first routing element, processing the identification messages coming from the second routing element solely as indicating that the second routing element is active;
• and
• in the second routing element, updating the routing table from the identification messages coming from the first routing element.