Technique for protecting leaf nodes of a point-to-multipoint tree in a communications network in connected mode
A technique protects, in a communications network, a point-to-multipoint primary tree between a root node and primary leaf nodes of the network if a failure occurs affecting one of the primary leaf nodes. One network node receives from another upstream network node a request to protect the primary tree via a backup branch leading to a backup leaf node situated downstream from said node, if a failure affecting one of the primary leaf nodes to be protected occurs, the backup leaf node being associated with the primary leaf node to be protected. If the node is connected directly to the downstream primary leaf node to be protected, it configures a backup routing rule for routing packets from an upstream primary branch to the downstream backup branch and, possibly, to the downstream primary branch(es) and is activated in the event of a failure affecting the primary leaf node to be protected.
1. A method of protecting, in a communications network in connected mode, a point-to-multipoint primary tree comprising a root node and primary leaf nodes of the network, said primary leaf nodes having no child nodes in the network, in the event of a failure at one of the primary leaf nodes, including the following steps executed by a node of the network:
receiving from another network node a request to protect the primary tree by at least one backup branch leading to a backup leaf node having no child node and situated downstream from said another node in the network in an event of a failure affecting at least one of the primary leaf nodes to be protected, the backup leaf node being associated with the primary leaf node to be protected;
if the node is upstream from at least one backup leaf node, configuring at least one activated secondary routing rule to route packets coming from an upstream backup branch to the downstream backup branch and, where appropriate, to downstream primary branches; and
if the node is connected directly to the downstream primary leaf node to be protected, configuring a backup routing rule to route packets from an upstream primary branch leading to a downstream backup branch and, if appropriate, to a primary downstream branch or branches that is activated in an event of a failure affecting said primary leaf node to be protected.
2. The protection method according to claim 1 , wherein a request for setting up the backup branch is associated with the protection request, the configuration step being effected when the backup branch from said node is set up to a downstream node.
3. The protection method according to claim 2 , wherein a request to set up the primary tree is associated with the protection request, the configuration step being effected when at least one primary branch from said node is set up to a downstream node.
4. The protection method according to claim 1 , further comprising, if a failure is detected affecting said primary leaf node to be protected, notifying said failure to the root node of the primary tree.
5. A protector node in a communications network in connected mode for a point-to-multipoint primary tree between a root node and primary leaf nodes of the network, the primary leaf nodes having no child nodes in the network, in the event of a failure at one of the primary leaf nodes, comprising:
a receiver comprising a processor for receiving from another network node a request to protect the primary tree via a backup branch leading to a backup leaf node situated downstream from said node, the backup leaf node having no child nodes in the network, in an event of a failure affecting said primary leaf node to be protected, the backup leaf node being associated with the primary leaf node to be protected;
a processor operative to execute a configuration routine for configuring at least one activated secondary routing rule to route packets coming from an upstream backup branch to the downstream backup branch and, where appropriate, to downstream primary branches; and
a processor operative to execute a configuration routine for configuring a backup routing rule to route packets from an upstream primary branch leading to a downstream backup branch and, if appropriate, to downstream primary branches activated in an event of a failure affecting the primary leaf node to be protected.
6. The protector node according to claim 5 , further comprising a notifier comprising a processor for sending a failure notification to the root node of the primary tree in the event of detection of a failure affecting a primary leaf node to be protected.
7. A communications system in a communications network in connected mode, comprising:
at least one root node, said root node being the root of a point-to-multipoint primary tree to primary leaf nodes, comprising a sender for sending a request to protect the primary tree via a backup branch to a backup leaf node situated downstream of said root node in an event of a failure affecting one of the primary leaf nodes to be protected, the backup leaf node being associated with the primary leaf node to be protected;
at least one protector node according to claim 6 ; and
primary and backup leaf nodes having no child nodes in the network.
8. A non-transitory computer program product comprising instructions for execution by a node of a communications network in connected mode when that program is executed by a processor of a method of protecting, in a communications network in connected mode, a point-to-multipoint primary tree between a root node and primary leaf nodes of the network, the primary leaf nodes having no child nodes in the network, in the event of a failure at one of the primary leaf nodes, including the following steps executed by the node:
receiving from another network node a request to protect the primary tree by at least one backup branch leading to a backup leaf node having no child nodes in the network and situated downstream from said node in an event of a failure affecting at least one of the primary leaf nodes to be protected, the backup leaf node being associated with the primary leaf node to be protected;
if the node is upstream from at least one backup leaf node, configuring at least one activated secondary routing rule to route packets coming from an upstream backup branch to the downstream backup branch and, where appropriate, to downstream primary branches; and
if the node is connected directly to the downstream primary leaf node to be protected, configuring a backup routing rule to route packets from an upstream primary branch leading to a downstream backup branch and, if appropriate, to a primary downstream branch or branches that is activated in an event of a failure affecting said primary leaf node to be protected.
9. A method for operating a communications network, comprising sending a signal by a node of a communications network to another node of the network and carrying a request to protect a point-to-multipoint primary tree between a root node and primary leaf nodes of the network, the primary leaf nodes having no child nodes in the network, in an event of a failure at one of the primary leaf nodes to be protected via a backup branch to a backup leaf node having no child nodes in the network and situated downstream of said other node, the backup leaf node being associated with the primary leaf node to be protected; the method comprising if said other node is upstream from at least one backup leaf node, configuring at least one activated secondary routing rule to route packets coming from an upstream backup branch to the downstream backup branch and, where appropriate, to downstream primary branches.