Enhanced procedure to compute LFAs with IGP max metric
First Claim
1. A method implemented by a network device in a network having a plurality of nodes, the method to calculate a loop free alternative (LFA) next hop as a backup for a next hop of a primary path for an interior gateway protocol (IGP), where the method enables consideration of the LFA next hop where a link to the next hop has a reverse cost that has a maximum value, where the maximum value is a maximum link metric defined for the network, a forward cost is a metric for an outbound direction from the network device on the link, the reverse cost is a metric for an inbound direction toward the network device on the link, the method comprising the steps of:
- selecting a next candidate next hop from a set of candidate next hops in the network;
checking whether a link to the next candidate next hop is an administratively allowable link;
checking whether the link has a maximum forward cost, where the maximum forward cost is a value defined for the network as a maximum possible value for a forward link cost;
checking whether the link is bi-directional;
computing LFA using the next candidate next hop where the link is administratively allowable link, where the link does not have the maximum forward cost, where the link is bi-directional, and where the link is considered for the LFA when the link has a reverse cost with the maximum value; and
updating a local routing information base of the network device to enable forwarding of data traffic using the computed LFA where the primary path has failed.
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Accused Products
Abstract
A method and implementing system calculates a loop free alternative (LFA) next hop as a backup for a primary path next hop for an interior gateway protocol (IGP). The method enables consideration of the LFA next hop where a link to the next hop has a reverse cost that has a maximum value. The method includes selecting a next candidate next hop from a set of candidate next hops in the network, checking whether a link to the next candidate next hop is an administratively allowable link, and checking whether the link has a maximum forward cost. The method further checks whether the link is bi-directional and computes the LFA using the next candidate next hop where the link is administratively allowable link, where the link does not have a maximum forward cost and where the link is bi-directional without consideration of reverse cost of the link.
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Citations
25 Claims
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1. A method implemented by a network device in a network having a plurality of nodes, the method to calculate a loop free alternative (LFA) next hop as a backup for a next hop of a primary path for an interior gateway protocol (IGP), where the method enables consideration of the LFA next hop where a link to the next hop has a reverse cost that has a maximum value, where the maximum value is a maximum link metric defined for the network, a forward cost is a metric for an outbound direction from the network device on the link, the reverse cost is a metric for an inbound direction toward the network device on the link, the method comprising the steps of:
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selecting a next candidate next hop from a set of candidate next hops in the network; checking whether a link to the next candidate next hop is an administratively allowable link; checking whether the link has a maximum forward cost, where the maximum forward cost is a value defined for the network as a maximum possible value for a forward link cost; checking whether the link is bi-directional; computing LFA using the next candidate next hop where the link is administratively allowable link, where the link does not have the maximum forward cost, where the link is bi-directional, and where the link is considered for the LFA when the link has a reverse cost with the maximum value; and updating a local routing information base of the network device to enable forwarding of data traffic using the computed LFA where the primary path has failed. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A network device in a network having a plurality of nodes, the network device to implement a method to calculate a loop free alternative (LFA) next hop as a backup for a next hop of a primary path for an interior gateway protocol (IGP), where the method enables consideration of the LFA next hop where a link to the next hop has a reverse cost that has a maximum value, where the maximum value is a maximum link metric defined for the network, a forward cost is a metric for an outbound direction from the network device on the link, the reverse cost is a metric for an inbound direction toward the network device on the link, the network device comprising:
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a non-transitory storage medium to store networking software; and a network processor communicatively coupled to the non-transitory storage medium, the network processor configured to execute an IGP module, the IGP module configured to select a next candidate next hop from a set of candidate next hops in the network, to check whether a link to the next candidate next hop is an administratively allowable link, to check whether the link has a maximum forward cost, where the maximum forward cost is a value defined for the network as a maximum possible value for a forward link cost, to check whether the link is bi-directional, to compute LFA using the next candidate next hop where the link is administratively allowable link, the link does not have the maximum forward cost and the link is bi-directional, and where the link is considered for the LFA when the link has a reverse cost with the maximum value, and to update a local routing information base of the network device to enable forwarding of data traffic using the computed LFA where the primary path has failed. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. 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 calculate a loop free alternative (LFA) next hop as a backup for a next hop of a primary path for an interior gateway protocol (IGP), where the centralized control plane enables consideration of the LFA next hop where a link to the next hop has a reverse cost that has a maximum value, where the maximum value is a maximum link metric defined for a network, a forward cost is a metric for an outbound direction from a network device on the link, the reverse cost is a metric for an inbound direction toward the network device on the link, the control plane device comprising:
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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 next hop from a set of candidate next hops in the network, to check whether a link to the next candidate next hop is an administratively allowable link, to check whether the link has a maximum forward cost, where the maximum forward cost is a value defined for the network as a maximum possible value for a forward link cost, to check whether the link is bi-directional, to compute LFA using the next candidate next hop where the link is administratively allowable link, the link does not have the maximum forward cost and the link is bi-directional, and where the link is considered for the LFA when the link has a reverse cost with the maximum value, and to update a local routing information base of the network device to enable forwarding of data traffic using the computed LFA where the primary path has failed. - View Dependent Claims (16, 17, 18, 19)
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20. 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 calculate a loop free alternative (LFA) next hop as a backup for a next hop of a primary path for an interior gateway protocol (IGP), where the NFV enables consideration of the LFA next hop where a link to the next hop has a reverse cost that has a maximum value, where the maximum value is a maximum link metric defined for a network, a forward cost is a metric for an outbound direction from a network device on the link, the reverse cost is a metric for an inbound direction toward the network device on the link, the computing device comprising:
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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 next hop from a set of candidate next hops in the network, to check whether a link to the next candidate next hop is an administratively allowable link, to check whether the link has a maximum forward cost, where the maximum forward cost is a value defined for the network as a maximum possible value for a forward link cost, to check whether the link is bi-directional, to compute LFA using the next candidate next hop where the link is administratively allowable link, the link does not have the maximum forward cost and the link is bi-directional, and where the link is considered for the LFA when the link has a reverse cost with the maximum value, and to update a local routing information base of the network device to enable forwarding of data traffic using the computed LFA where the primary path has failed. - View Dependent Claims (21, 22, 23, 24, 25)
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Specification