Authors: Damien Magoni ^1,2; Jean-Jacques Pansiot ^1,2

• 1 Laboratoire des Sciences de l'Image, de l'Informatique et de la Télédétection
• 2 Laboratoire de Sciences de l'Image, de l'Informatique et de la Télédétection, équipe ICPS

Many protocols need a discovery mechanism to enable a given node to locate one or several nodes involved in the same communication. However, there is no protocol ready to fulfill this service at the network-layer. Every protocol usually implements its own solution. In particular, multicast protocols often use a searching technique based on an algorithm called expanding ring search. This algorithm searches for nodes in all directions and thus uses much bandwidth. However a typical search can usually restrict its scan in a specific direction. To enable this broadcast restriction, we propose an oriented multicast routing algorithm. The algorithm's principle is to direct the multicast of packets towards a special node, involved in the communication, in order to search only in a limited area. The area must be as small as possible to reduce network flooding but still has to contain many nodes satisfying the search criteria. This new algorithm is the core part of a network-level node search framework also defined herein. A search protocol based on this framework could provide a network-level agent discovery service to current protocols. We have simulated an agent search with our algorithm on one side and with the expanding ring algorithm on the other side and we give comparative results.