Method for fast-re-routing (FRR) in communication networks
View Patent ↗A method is described to enable carrying out a fast reroute protection technique which provides both link and node protection without traffic duplication, without the need to distinguish between link and node failures, and without replicating traffic. The technique covers concurrent Working and backup logical path failures, and in particular LSP logical paths. The method is adapted to provide a “Dual Failure Protection” (DFP), and is expandable to various multi-failure scenarios.
1. A method for fast rerouting (FRR) of traffic in a communication network, from a Working path comprising a first node being a point of local repair (PLR), a link connecting the first node with a second, downstream node being a next hop node (NH), and a third node positioned downstream to said second node along said Working path being a next-next hop node (NNH); the method comprises:
pre-provisioning a point-to-multipoint (P2MP) backup path having a start point at the PLR and two termination points being the NH and the NNH,
pre-provisioning, in said P2MP backup path, a node PH being a penultimate hop to the NH, so that the PH is directly connected to the NH;
wherein the P2MP backup path comprising two sub-paths, a first extending between the PLR and the NH, and a second between the PLR and the NNH, and wherein the two sub-paths are identical until they branch off at the penultimate hop (PH);
concurrently providing link protection against failure of said link between the PLR and NH, and node protection against failure of said NH, thereby ensuring concurrent FRR for said link and said NH by implementing at said PH node a forwarding rule enabling to forward traffic, if received at the PH along said P2MP backup path, towards said NH in case the NH is UP, and downstream the P2MP backup path towards said NNH in case said the NH is DOWN.
2. The method according to claim 1 , for use in an MPLS network and wherein traffic is rerouted from the Working path being a label switched path (LSP) which comprises the first node being point of local repair (PLR), the link connecting the first node and the second, downstream node (NH), and at least one said third node (NNH) positioned downstream to said second node (NH); and the backup path being a backup LSP.
3. The method according to claim 1 , wherein said Working path and said backup path are a point-to-point (P2P) LSP and a point-to-multipoint (P2MP) LSP respectively.
4. The method according to claim 1 , adapted to perform an FRR process in a ring-like communication network.
5. The method according to claim 1 , adapted to perform double failure protection (DFP).
6. The method according to claim 5 , wherein the network comprises two rings interconnected by a dual homed node (DH), and wherein the method further comprising:
arranging the Working LSP and said backup LSP so as to pass via both of said two rings, and for the backup path to include the DH; and
selecting the DH node to be the PH node.
7. The method according to claim 3 , wherein a Working LSP spanning ring networks is protected by n P2MP backup LSPs, one P2MP backup LSP per ring network.
8. A software product encoding a computer program stored on a non-transitory computer readable storage medium for executing a set of instructions by an apparatus comprising one or more computer processors, for carrying out the method of claim 1 .
9. A method for non-Label Distribution Protocol (non-LDP) fast rerouting (FRR) of traffic in a communication network, from a Working path comprising a first node being a point of local repair (PLR), a link connecting the first node with a second, downstream node being a next hop node (NH), and a third node positioned downstream to said second node along said Working path being a next-next hop node (NNH); the method comprises:
pre-provisioning a point-to-multipoint (P2MP) backup path having a start point at the PLR and two termination points being the NH and the NNH,
pre-provisioning, in said P2MP backup path, a node PH being a penultimate hop to the NH, so that the PH is directly connected to the NH;
wherein the P2MP backup path comprising two sub-paths, a first extending between the PLR and the NH, and a second between the PLR and the NNH, and wherein the two sub-paths are identical until they branch off at the penultimate hop (PH);
concurrently providing link protection against failure of said link between the PLR and NH, and node protection against failure of said NH, thereby ensuring concurrent FRR for said link and said NH by implementing at said PH node a forwarding rule enabling to forward traffic, if received at the PH along said P2MP backup path, towards said NH in case the NH is UP, and downstream the P2MP backup path towards said NNH in case said the NH is DOWN.