Path weighted equal-cost multipath

A network device comprising:

• a control unit comprising one or more processors;
• a routing protocol software of the control unit to receive a link bandwidth for each of one or more network links of a network that are positioned between the network device and a second network device of the network,
• wherein the routing protocol software is adapted to execute a routing protocol to select plurality of forwarding paths from the network device to the second network device that each satisfy a constraint;
• a path weight calculator of the control unit to determine that one of the network links is a common network link shared by multiple forwarding paths of the plurality of forwarding paths and positioned between the second network device and a downstream router that is positioned between the network device and the second network device along at least one of the forwarding paths, and, in response to determining that the one of the network links is a common network link shared by multiple of the plurality of forwarding paths, compute an amount of bandwidth that can be sent on an outgoing interface of the network device to a neighbor node on the multiple forwarding paths that share the one of the network links, wherein in computing the amount of bandwidth the path weight calculator (i) accounts for splitting of the link bandwidth of the shared network link across the multiple forwarding paths that share the common network link, and (ii) when the first router determines that the downstream router is not configured to account for splitting of the link bandwidth for the common network link across the multiple forwarding paths that share the common network link when the downstream router computes an amount of bandwidth that can be sent on an outgoing interface of the downstream router, computing the bandwidth based on a capability of the downstream router in load balancing received traffic across multiple next hops of the downstream router;
• a multipath forwarding component of the control unit to selectively assign packet flows to each of a plurality of outgoing interfaces of the network device based at least on the computed amount of bandwidth;
• and
• one or more interface cards to receive packets for the packet flows,
• wherein the multipath forwarding component forwards packets of each of the packets flows to the respective one of the plurality of outgoing interfaces to which the packet flow is assigned.

A non-transitory computer-readable storage medium comprising instructions for causing a programmable processor to:

• receive a link bandwidth for each of one or more network links of a network that are positioned between a first router and a second router of the network;
• select a plurality of forwarding paths from the first router to the second router that each satisfy a constraint;
• determine that one of the network links is a common network link shared by multiple forwarding paths of the plurality of forwarding paths and positioned between the second router and a downstream router that is positioned between the first router and the second router along at least one of the forwarding paths;
• compute an amount of bandwidth that can be sent on an outgoing interface of the first router to a neighbor node on the multiple forwarding paths that share the one of the network links, wherein computing the amount of bandwidth comprises (i) accounting for splitting of the link bandwidth of the common network link across the multiple forwarding paths that share the common network link, and (ii) when the first router determines that the downstream router is not configured to account for splitting of the link bandwidth for the common network link across the multiple forwarding paths that share the common network link when the downstream router computes an amount of bandwidth that can be sent on an outgoing interface of the downstream router, computing the bandwidth based on a capability of the downstream router in load balancing received traffic across multiple next hops of the downstream router;
• selectively assign packet flows to each of a plurality of outgoing interfaces of the first router based at least on the computed amount of bandwidth;
• receive packets for the packet flows with the first router;
• and
• forward packets of each of the packets flows to the respective one of the plurality of outgoing interfaces to which the packet flow is assigned.