Alternate method to give operators flexibility to choose LFAs

A network device in a network having a plurality of nodes, the network device configured to compute a loop free alternative (LFA) next hop as a backup for a primary path next hop node for an interior gateway protocol (IGP), where the method enables an administrator to control LFA selection for a given destination node using a tag and a weight, the network device comprising:

• a non-transitory machine-readable storage medium to store an IGP module;
• and
• a network processor communicatively coupled to the non-transitory machine-readable storage medium, the network processor to execute the IGP module, the IGP module configured to select a next candidate node from a set of neighbor nodes in the network to perform LFA computation, determine whether an interface of the next candidate node towards a source node, provides an LFA for the destination node, check whether the interface of the next candidate node has a tag with a tag value matching a tag value of a primary SPF path for the destination node, check whether the destination node has any LFA, check whether a stored tag differs from the tag value of the primary SPF path for the destination node, check whether the interface of the next candidate node is preferred based on a comparison of a weight value of the interface of the next candidate node and a stored weight, replace a stored LFA for the destination node with the next candidate node, a stored weight with a weight of the interface of the next candidate node, and a stored tag with a tag of the interface of the next candidate node;
• and download the stored LFA to a global routing information base after all candidate nodes have been exhausted.

A control plane device configured to implement at least one centralized control plane for a software defined network (SDN), the centralized control plane configured to execute a method to compute a loop free alternative (LFA) next hop as a backup for a primary path next hop for an interior gateway protocol (IGP), where the method enables an administrator to control LFA selection for a given destination node using a tag and a weight, the control plane device comprising:

• a non-transitory storage medium to store centralized control plane software and an IGP module;
• and
• a processor communicatively coupled to the non-transitory storage medium, the processor configured to execute the control plane software to implement the IGP module, the IGP module configured to select a next candidate node from a set of neighbor nodes in the network to perform LFA computation, determine whether an interface of the next candidate node towards a source node, provides an LFA for the given destination node, check whether the interface of the next candidate node has a tag with a tag value matching a tag value of a primary SPF path for the destination node, check whether the destination node has any LFA, check whether a stored tag differs from the tag value of the primary SPF path for the destination node, check whether the interface of the next candidate node is preferred based on a comparison of a weight value of the interface of the next candidate node and a stored weight, replace a stored LFA for the destination node with the next candidate node, a stored weight with a weight of the interface of the next candidate node, and a stored tag with a tag of the interface of the next candidate node, and download the stored LFA to a global routing information base after all candidate nodes have been exhausted.

A computing device implementing a plurality of virtual machines for implementing network function virtualization (NFV), wherein a virtual machine from the plurality of virtual machines is configured to execute a method to compute a loop free alternative (LFA) next hop as a backup for a primary path next hop for an interior gateway protocol (IGP), where the method enables an administrator to control LFA selection for a given destination node using a tag and a weight, the computing device comprising:

• a non-transitory storage medium to store an IGP module;
• and
• a processor communicatively coupled to the non-transitory storage medium, the processor configured to execute the IGP module, the IGP module configured to select a next candidate node from a set of neighbor nodes in the network to perform LFA computation, determine whether an interface of the next candidate node towards a source node, provides an LFA for the destination node, check whether the interface of the next candidate node has a tag with a tag value matching a tag value of a primary SPF path for the destination node, check whether the destination node has any LFA, check whether a stored tag differs from the tag value of the primary SPF path for the destination node, check whether the interface of the next candidate node is preferred based on a comparison of a weight value of the interface of the next candidate node and a stored weight, replace a stored LFA for the destination node with the next candidate node, a stored weight with a weight of the interface of the next candidate node, and a stored tag with a tag of the interface of the next candidate node, and download the stored LFA to a global routing information base after all candidate nodes have been exhausted.