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

1. 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.

2. The method according to claim 1 , wherein the second routing element is configured not to issue update messages to the first routing element.

3. The method according to claim 1 , wherein the first network is identified globally in the neighborhood identification fields of the identification messages issued by the first routing element that is actually associated with the first network.

4. The method according to claim 1 , wherein the routing elements are between the first and second networks and not part of either network.

5. An aircraft having an on-board network comprising an avionics network and a public network, each made up of network elements, and connected to each other via at least two first routing elements that are selectively associated with the avionics network, and by at least one second routing element that is associated with the public network and that is connected to the first routing elements, the avionics network implementing a routing protocol using static routing tables, and the public 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, wherein:

each first routing element is configured for 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;

each first routing element is configured for processing the identification messages coming from the second routing element solely as indicating that the second routing element is active; and

the second routing element is configured for updating its routing table from the identification messages coming from the first routing element.

6. The aircraft according to claim 5 , wherein the second routing element is configured not to issue update messages to the first routing element.

7. The aircraft according to claim 5 , wherein the avionics network is identified globally in the neighborhood identification fields of the identification messages issued by the first routing element that is actually associated with the avionics network.