Abstract: In one embodiment, a method includes monitoring traffic in a Segment Routing (SR) network through a collection of a Segment Routing Demand Matrix (SRDM) at a Traffic Engineering (TE) system operating at a network device, receiving topology information for the SR network at the TE system, modeling the SR network based on the topology information and the SRDM at the TE system, identifying a violation of a constraint in the SR network at the TE system, and running an optimization algorithm for SR optimization of constraints in the SR network at the TE system, wherein the optimization comprises limiting a number of Segment Identifiers (SIDs) used in a SR policy implemented to resolve the constraint violation. An apparatus is also disclosed herein.

Abstract: In one embodiment, a device in a network identifies a shortest path tree for a point of local repair in the network that excludes at least one link between the point of local repair and a neighbor of the point of local repair in the network. The device evaluates member nodes of a branch of the shortest path tree, to form a list of repair segments. The device further causes one or more segment routing labels to be added to a header of a packet based on the repair segment list and in response to a failure in the network associated with the at least one link excluded from the shortest path tree.

Abstract: In one embodiment, a method includes monitoring traffic in a Segment Routing (SR) network through a collection of a Segment Routing Demand Matrix (SRDM) at a Traffic Engineering (TE) system operating at a network device, receiving topology information for the SR network at the TE system, modeling the SR network based on the topology information and the SRDM at the TE system, identifying a violation of a constraint in the SR network at the TE system, and running an optimization algorithm for SR optimization of constraints in the SR network at the TE system, wherein the optimization comprises limiting a number of Segment Identifiers (SIDs) used in a SR policy implemented to resolve the constraint violation. An apparatus is also disclosed herein.

Abstract: In one embodiment, a method includes monitoring traffic in a Segment Routing (SR) network through a collection of a Segment Routing Demand Matrix (SRDM) at a Traffic Engineering (TE) system operating at a network device, receiving topology information for the SR network at the TE system, modeling the SR network based on the topology information and the SRDM at the TE system, identifying a violation of a constraint in the SR network at the TE system, and running an optimization algorithm for SR optimization of constraints in the SR network at the TE system, wherein the optimization comprises limiting a number of Segment Identifiers (SIDs) used in a SR policy implemented to resolve the constraint violation. An apparatus is also disclosed herein.

Abstract: In one embodiment, a method includes monitoring traffic in a Segment Routing (SR) network through a collection of a Segment Routing Demand Matrix (SRDM) at a Traffic Engineering (TE) system operating at a network device, receiving topology information for the SR network at the TE system, modeling the SR network based on the topology information and the SRDM at the TE system, identifying a violation of a constraint in the SR network at the TE system, and running an optimization algorithm for SR optimization of constraints in the SR network at the TE system, wherein the optimization comprises limiting a number of Segment Identifiers (SIDs) used in a SR policy implemented to resolve the constraint violation. An apparatus is also disclosed herein.

Abstract: In one embodiment, a controller device in a computer network domain learns border gateway protocol (BGP) egress peering segments from one or more border routers of the domain, and determines a selected flow to segment route via a particular egress peering segment, the selected flow from a given routing device within the domain to a given destination of a remote domain. As such, the controller device may then instruct the given routing device to segment route the selected flow via the particular egress peering segment. In another embodiment, an egress border router shares its BGP egress peering segments, and receives a flow to segment route. The egress border router may determine, from a segment route contained within the flow, to which particular egress peering segment of the border router to segment route the flow, and forwards the flow out of the domain via the particular egress peering segment.

Abstract: In one embodiment, a method comprises generating, by a first provider edge router associated with a first segment identifier, a primary label for reaching a destination, and repair information for reaching the destination if a second provider edge router is unavailable to reach the destination; allocating, by the first provider edge router, a first protected next-hop address associated with the first segment identifier for protected reachability to at least the destination; and sending via a core network, by the first provider edge router, an advertisement specifying the label and the repair information, enabling an ingress provider edge router to insert, into a data packet destined for the destination, the labels from the first provider edge router and the second provider edge router based on the repair information, for fast rerouting to the destination via one of the first or second provider edge router if the other is unavailable.

Abstract: In one embodiment, a method comprises selecting, by an ingress provider edge router, one of first or second provider edge routers as a primary router for reaching a destination via a core network, and selecting the other of the first or second provider edge routers as a backup router for reaching the destination via the core network; and inserting, into an IPv6 data packet destined for the destination, a primary label assigned by the primary router and a repair label assigned by backup router, and an IPv6 extension header specifying first and second segment identifiers associated with the respective first and second provider edge routers and a protected flag that enables fast rerouting of the IPv6 data packet to the backup router if the primary router is unavailable.

Abstract: Various techniques can be used to avoid loops during network convergence after a topology change such as a failure. For example, a method can involve detecting a failure that disrupts an existing forwarding path between a node and a destination node; calculating at least one updated forwarding path from the node to the destination node; identifying a maximum time for at least a portion of the network to reach a post-convergence state with respect to the failure; until the maximum time has elapsed at the node, explicitly specifying at least a portion of the updated forwarding path in packet headers of any packets being sent from the node to the destination node; and after the maximum time has elapsed at the node, non-explicitly specifying the portion of the updated forwarding path in packet headers of any additional packets being sent from the node to the destination node.

Abstract: Various techniques can be used to avoid loops during network convergence after a topology change such as a failure. For example, a method can involve detecting a failure that disrupts an existing forwarding path between a node and a destination node; calculating at least one updated forwarding path from the node to the destination node; identifying a maximum time for at least a portion of the network to reach a post-convergence state with respect to the failure; until the maximum time has elapsed at the node, explicitly specifying at least a portion of the updated forwarding path in packet headers of any packets being sent from the node to the destination node; and after the maximum time has elapsed at the node, non-explicitly specifying the portion of the updated forwarding path in packet headers of any additional packets being sent from the node to the destination node.

Abstract: In one embodiment, a controller device in a computer network domain learns border gateway protocol (BGP) egress peering segments from one or more border routers of the domain, and determines a selected flow to segment route via a particular egress peering segment, the selected flow from a given routing device within the domain to a given destination of a remote domain. As such, the controller device may then instruct the given routing device to segment route the selected flow via the particular egress peering segment. In another embodiment, an egress border router shares its BGP egress peering segments, and receives a flow to segment route. The egress border router may determine, from a segment route contained within the flow, to which particular egress peering segment of the border router to segment route the flow, and forwards the flow out of the domain via the particular egress peering segment.

Abstract: In one embodiment, a method comprises generating, by a first provider edge router associated with a first segment identifier, a primary label for reaching a destination, and repair information for reaching the destination if a second provider edge router is unavailable to reach the destination; allocating, by the first provider edge router, a first protected next-hop address associated with the first segment identifier for protected reachability to at least the destination; and sending via a core network, by the first provider edge router, an advertisement specifying the label and the repair information, enabling an ingress provider edge router to insert, into a data packet destined for the destination, the labels from the first provider edge router and the second provider edge router based on the repair information, for fast rerouting to the destination via one of the first or second provider edge router if the other is unavailable.

Abstract: In one embodiment, a method comprises selecting, by an ingress provider edge router, one of first or second provider edge routers as a primary router for reaching a destination via a core network, and selecting the other of the first or second provider edge routers as a backup router for reaching the destination via the core network; and inserting, into an IPv6 data packet destined for the destination, a primary label assigned by the primary router and a repair label assigned by backup router, and an IPv6 extension header specifying first and second segment identifiers associated with the respective first and second provider edge routers and a protected flag that enables fast rerouting of the IPv6 data packet to the backup router if the primary router is unavailable.