Method for turning off routers in a communications network and router implementing this method

1. A method for turning off routers, operating according to a link-state protocol, in a communications network, said network linking a plurality of devices, said method being executed simultaneously over a plurality of routers of the network and including:

a step of initializing,

a step of monitoring verifying a list of predefined conditions to be met to allow the turning off of the router,

a step of waiting,

a step of turning off, including a transmission of a message destined for other routers executing said method to signal the turning off of said router to the other routers,

the waiting step being carried out before the turning-off step, the turning-off step being carried out only if no turning-off message originating from other routers is received during the waiting step, and if at least one of the following conditions is verified:

the router is not in the process of transferring traffic,

the router is not executing other applications, or

turning off the router does not lead to a disconnection of at least one of the devices,

a verification of the condition according to which turning off the router does not lead to the disconnection of at least one of the devices of the network includes:

a step of determining a graph representing a topology of the network using information resulting from the link-state protocol, the graph including nodes representing the devices and links representing connections between the devices,

a step of selecting a neighbor node to a node representing the router,

a step of depth searching, from the selected neighbor node, the graph of the network from which the node representing the router was previously withdrawn,

a step of verifying that all the nodes are accessible from the neighbor node,

if said verification step is valid then said condition according to which turning off the router does not lead to the disconnection of at least one of the devices is verified, otherwise the condition according to which turning off the router does not lead to the disconnection of at least one of the devices is not verified; and

if a turning-off message coming from other routers is received during the waiting step, then a return to the monitoring step is carried out.

2. The method as claimed in claim 1 , further comprising an additional waiting step, the duration of which is parameterized, intended to take into account the propagation time of the messages in the network.

3. The method as claimed in claim 1 , in which the duration of the waiting step is determined according to a pseudo-random method, so as to avoid several routers being turned off simultaneously.

4. The method as claimed in claim 1 , in which the duration of the waiting step is parameterized as a function of the quality of service of the router on which the method is executed; and the higher the quality of service of the router, the longer the duration of the waiting step.

5. The method as claimed in claim 4 , in which the quality of service of the router is evaluated from at least one characteristic chosen from the following: a speed, a delay or a security level of the router.

6. A router configured to operate according to a link-state protocol, in a communications network, the network linking a plurality of devices, comprising:

the router configured to implement a step of initializing, the router configured to implement a step of monitoring verifying a list of predefined conditions to be met to allow the turning off of the router,

the router configured to implement a step of waiting,

the router configured to implement a step of turning off, including a transmission of a message destined for other routers to signal the turning off of said router to the other routers,

wherein the waiting step being carried out before the turning-off step, the turning-off step being carried out only if no turning-off message originating from other routers is received during the waiting step, and if at least one of the following conditions is verified:

the router is not in the process of transferring traffic,

the router is not executing other applications, or

turning off the router does not lead to a disconnection of at least one of the devices,

the router configured to implement a verification of the condition according to which turning off the router does not lead to the disconnection of at least one of the devices of the network includes:

a step of determining a graph representing a topology of the network using information resulting from the link-state protocol, the graph including nodes representing the devices and links representing connections between the devices,

a step of selecting a neighbor node to a node representing the router,

a step of depth searching, from the selected neighbor node, the graph of the network from which the node representing the router was previously withdrawn,

the router configured to implement a step of verifying that all the nodes are accessible from the neighbor node,

the router configured to determine if said verification step is valid then said condition according to which turning off the router does not lead to the disconnection of at least one of the devices is verified, otherwise the condition according to which turning off the router does not lead to the disconnection of at least one of the devices is not verified; and

the router configured to determine if a turning-off message coming from other routers is received during the waiting step, then a return to the monitoring step is carried out.

7. A telecommunications network comprising a plurality of routers as claimed in claim 6 .