Section: New Results

Specific studies: network maintenance

Participants : Eric Fabre, Carole Hounkonnou.

This work represents part of our activities within the research group “High Manageability,” supported by the common lab of Alcatel-Lucent Bell Labs (ALBLF) and INRIA. It concerns a methodology for the graceful shut down and restart of routers in OSPF networks, one of the core protocols of IP networks. A methodology has been proposed to safely switch off the software layer of a router while still maintaining this router in the forwarding plane: the router still forwards packets, but is not able to adapt its routing table to changes in network conditions or topology. Nevertheless, it is possible to check whether this frozen router is harmless or can cause packet losses, through a centralized or distributed algorithm. And if ever it puts the network at risk, minimal patches can be set up temporarily until the router comes back to normal a activity. This avoids running twice a global OSPF update at all nodes (once for shutdown of the equipment, one for restart). There is a patent project on this activity, that we don't detail more here.