Abstract: An example network element includes one or more interfaces and a control unit, the control unit includes one or more processors configured to determine an egress network domain identifier (ID) and determine an abstracted interdomain network topology. The one or more processors are also configured to determine one or more interdomain paths from an abstracted ingress domain node to an abstracted egress domain node and determine whether an abstracted domain node is on the one or more interdomain paths. The one or more processors are configured to, based on the abstracted domain node being on the one or more interdomain paths, include one or more resources within a network domain in a filtered traffic engineering database (TED) and compute a path from an ingress node within the ingress network domain to an egress node within the egress network domain based on the filtered TED.

Abstract: The disclosed computer-implemented method may include (1) receiving, at a network node within a network, a packet from another network node within the network, (2) identifying, within the packet, a label stack that includes a plurality of labels that collectively represent at least a portion of a label-switched path within the network, (3) popping, from the label stack, a label that corresponds to a next hop of the network node, (4) determining, based at least in part on the label, that the next hop has experienced a failure that prevents the packet from reaching a destination via the next hop, (5) identifying a backup path that merges with the label-switched path at a next-to-next hop included in the label-switched path, and then (6) forwarding the packet to the next-to-next hop via the backup path. Various other methods, systems, and apparatuses are also disclosed.

Abstract: Techniques are described for class-based traffic engineering in an IP network. For example, routers of an IP network may establish one or more constrained traffic engineered paths using a link-state protocol (e.g., IGP) without using signaling protocols, such as RSVP or SPRING, or encapsulating packets over MPLS. For example, an egress router of the IP network may receive a capability message specifying the capability of routers to compute a constrained path to the egress router, wherein the capability message comprises path computation information including an identifier of a path computation algorithm to be used by the one or more of the plurality of network devices to reach the egress network device. The egress router may advertise a reachability message including a destination IP prefix and the identifier of the path computation algorithm to cause routers in the IP network to compute the constrained path to reach the egress router.

Abstract: A ring node N belonging to a resilient MPLS ring (RMR) provisions and/or configures clockwise (CW) and anti-clockwise (AC) paths on the RMR by: (a) configuring two ring node segment identifiers (Ring-SIDs) on the ring node, wherein a first of the two Ring-SIDs (CW-Ring-SID) is to reach N in a clockwise direction on the ring and a second of the two Ring-SIDs (AC-Ring-SID) is to reach N in an anti-clockwise direction on the ring, and wherein the CW-Ring-SID and AC-Ring-SID are unique within a source packet routing in networking (SPRING) domain including the ring; (b) generating a message including the ring node's CW-Ring-SID and AC-Ring-SID; and (c) advertising the message, via an interior gateway protocol, for receipt by other ring nodes belonging to the ring such that (1) a clockwise multipoint-to-point path (CWP) is defined such that every other one of the ring nodes belonging to the ring can be an ingress for the CWP and such that only the node is an egress for the CWP, and (2) an anti-clockwise multipoint-

Abstract: In general, this disclosure describes a network device that checks consistency between routing objects in a routing information base (RIB), a forwarding information base (FIB), and packet forwarding engine (PFE) forwarding tables. A method includes generating a marker that causes a routing protocol daemon, a control plane kernel, and PFEs of a network device to calculate zonal checksums for a plurality of zones using consistency values for each routing object within a RIB, a FIB, and corresponding forwarding tables respectively. The method includes performing a consistency check on the RIB, the FIB, and the forwarding tables to determine whether the routing objects in each of the RIB, the FIB, and the forwarding tables are consistent with each other. The method includes, when the RIB, the FIB, and the forwarding tables are not consistent, performing an action related to at least one of RIB, the FIB, or the forwarding tables.

Abstract: In general, this disclosure describes a network device to determine a cause of packets being dropped within a network. An example method includes generating, by a traffic monitor operating on a network device, an exception packet that includes a unique exception code that identifies a cause for a component in the network device to discard a transit packet, and a nexthop index identifying a forwarding path being taken by the transit packet experiencing the exception. The method also includes forwarding the exception packet to a collector to be processed.

Abstract: In general, this disclosure describes a network device that checks consistency between routing objects in a routing information base (RIB), a forwarding information base (FIB), and packet forwarding engine (PFE) forwarding tables. A method includes generating a marker that causes a routing protocol daemon, a control plane kernel, and PFEs of a network device to calculate zonal checksums for a plurality of zones using consistency values for each routing object within a RIB, a FIB, and corresponding forwarding tables respectively. The method includes performing a consistency check on the RIB, the FIB, and the forwarding tables to determine whether the routing objects in each of the RIB, the FIB, and the forwarding tables are consistent with each other. The method includes, when the RIB, the FIB, and the forwarding tables are not consistent, performing an action related to at least one of RIB, the FIB, or the forwarding tables.

Abstract: A ring node N belonging to a resilient MPLS ring (RMR) provisions and/or configures clockwise (CW) and anti-clockwise (AC) paths on the RMR by: (a) configuring two ring node segment identifiers (Ring-SIDs) on the ring node, wherein a first of the two Ring-SIDs (CW-Ring-SID) is to reach N in a clockwise direction on the ring and a second of the two Ring-SIDs (AC-Ring-SID) is to reach N in an anti-clockwise direction on the ring, and wherein the CW-Ring-SID and AC-Ring-SID are unique within a source packet routing in networking (SPRING) domain including the ring; (b) generating a message including the ring node's CW-Ring-SID and AC-Ring-SID; and (c) advertising the message, via an interior gateway protocol, for receipt by other ring nodes belonging to the ring such that (1) a clockwise multipoint-to-point path (CWP) is defined such that every other one of the ring nodes belonging to the ring can be an ingress for the CWP and such that only the node is an egress for the CWP, and (2) an anti-clockwise multipoint-

Abstract: Support is provided for flexible algorithms, used by the border gateway protocol (BGP) route selection process, in the context of segment routing (SR) Prefix segment identifiers (SIDS) advertised using BGP.

Abstract: At least one bandwidth-guaranteed segment routing (SR) path through a network is determined by: (a) receiving, as input, a bandwidth demand value; (b) obtaining network information; (c) determining a constrained shortest multipath (CSGi); (d) determining a set of SR segment-list(s) (Si=[sl1i, sl2i . . . slni]) a that are needed to steer traffic over CSGi; and (e) tuning the loadshares in Li, using Si and the per segment-list loadshare (Li=[l1i, l2i . . . lni]), the per segment equal cost multipath (“ECMP”), and the per link residual capacity, such that the bandwidth capacity that can be carried over CSGi is maximized.

Abstract: A node of an LSP may inform the ingress node of the LSP, for example via RSVP signaling, about its temporary unavailability for a certain time. In response, the ingress node can stop using any affected LSP(s) and divert the traffic to other LSPs. This provides a faster mechanism to signal traffic shift then traditional IGP overload which causes considerable churn into the network as all the nodes need to compute the SPF. It is sufficient for ingress node to be aware of this node maintenance and it can use information to divert the traffic to other equal cost multipath (ECMP) LSP(s), or other available LSP(s). If no alternative LSP path exists when the ingress node receives such a message, a new LSP can be built during this time and traffic diverted smoothly (e.g., in a make-before-break manner) before the node goes offline for maintenance.

Abstract: The same prefix segment identifier (SID) may be configured and/or used for either (A) more than one prefix within an interior gateway protocol (IGP) domain, or (B) one prefix with more than one path computation algorithm within the IGP domain by: (a) receiving, by a node in the IGP domain, an IGP advertisement including both (1) a prefix SID and a segment routing global block (SRGB) slice identifier; (b) determining whether or not the SRGB slice identified by the SRGB slice identifier is provisioned on the node; and (c) responsive to a determination that the SRGB slice identified by the SRGB slice identifier is not provisioned on the node, not processing the prefix SID included in the received IGP advertisement, and otherwise responsive to a determination that the SRGB slice identified by the SRGB slice identifier is provisioned on the node, (1) processing the prefix SID and SRGB slice to generate a unique, per SRGB slice, MPLS label for the prefix, and (2) updating a label forwarding information base (LFIB)

Abstract: At least one bandwidth-guaranteed segment routing (SR) path through a network is determined by: (a) receiving, as input, a bandwidth demand value; (b) obtaining network information; (c) determining a constrained shortest multipath (CSGi); (d) determining a set of SR segment-list(s) (Si=[sl1i, sl2i . . . slni]) a that are needed to steer traffic over CSGi; and (e) tuning the loadshares in Li, using Si and the per segment-list loadshare (Li=[l1i, l2i . . . lni]), the per segment equal cost multipath (“ECMP”), and the per link residual capacity, such that the bandwidth capacity that can be carried over CSGi is maximized.

Abstract: A ring node N belonging to a resilient MPLS ring (RMR) provisions and/or configures clockwise (CW) and anti-clockwise (AC) paths on the RMR by: (a) configuring two ring node segment identifiers (Ring-SIDs) on the ring node, wherein a first of the two Ring-SIDs (CW-Ring-SID) is to reach N in a clockwise direction on the ring and a second of the two Ring-SIDs (AC- Ring-SID) is to reach N in an anti-clockwise direction on the ring, and wherein the CW-Ring-SID and AC- Ring-SID are unique within a source packet routing in networking (SPRING) domain including the ring; (b) generating a message including the ring node's CW-Ring-SID and AC-Ring-SID; and (c) advertising the message, via an interior gateway protocol, for receipt by other ring nodes belonging to the ring such that (1) a clockwise multipoint-to-point path (CWP) is defined such that every other one of the ring nodes belonging to the ring can be an ingress for the CWP and such that only the node is an egress for the CWP, and (2) an anti-clockwise multipoin

Abstract: Techniques are described for class-based traffic engineering in an IP network. For example, routers of an IP network may establish one or more constrained traffic engineered paths using a link-state protocol (e.g., IGP) without using signaling protocols, such as RSVP or SPRING, or encapsulating packets over MPLS. For example, an egress router of the IP network may receive a capability message specifying the capability of routers to compute a constrained path to the egress router, wherein the capability message comprises path computation information including an identifier of a path computation algorithm to be used by the one or more of the plurality of network devices to reach the egress network device. The egress router may advertise a reachability message including a destination IP prefix and the identifier of the path computation algorithm to cause routers in the IP network to compute the constrained path to reach the egress router.

Abstract: In general, techniques are described for signaling IP path tunnels for traffic engineering using constraints in an IP network. For example, network devices, e.g., routers, of an IP network may compute an IP path using constraint information and establish the IP path using, for example, Resource Reservation Protocol, to signal the IP path without using MPLS. As one example, the egress router generates a path reservation signaling message that includes an egress IP address that is assigned for use by the routers on the IP path to send traffic of the data flow by encapsulating the traffic with the egress IP address and forwarding toward the egress router. As each router in the IP path receives the path reservation signaling message, the router configures a forwarding state to forward traffic encapsulated with the egress IP address to a next hop along the IP path toward the egress router.

Abstract: A node of an LSP may inform the ingress node of the LSP, for example via RSVP signaling, about its temporary unavailability for a certain time. In response, the ingress node can stop using any affected LSP(s) and divert the traffic to other LSPs. This provides a faster mechanism to signal traffic shift then traditional IGP overload which causes considerable churn into the network as all the nodes need to compute the SPF. It is sufficient for ingress node to be aware of this node maintenance and it can use information to divert the traffic to other equal cost multipath (ECMP) LSP(s), or other available LSP(s). If no alternative LSP path exists when the ingress node receives such a message, a new LSP can be built during this time and traffic diverted smoothly (e.g., in a make-before-break manner) before the node goes offline for maintenance.

Abstract: A control device may subscribe to receive data from a network device. The data may be associated with a plurality of packets that have been dropped by the network device and include a first descriptor based on a type of packet drop associated with a packet of the plurality of packets that have been dropped by the network device, and one or more second descriptors based on a packet flow associated with the plurality of packets that have been dropped by the network device. The control device may determine a dropped packet profile associated with the network device, based on the first descriptor and the one or more second descriptors. The control device may generate a first notification based on the dropped packet profile associated with the network device and transmit the first notification to cause an action to be performed based on the first notification.

Abstract: The disclosed computer-implemented method may include (1) receiving, at a network node within a network, a packet from another network node within the network, (2) identifying, within the packet, a label stack that includes a plurality of labels that collectively represent at least a portion of an LSP within the network, (3) popping, from the label stack, a label that corresponds to a specific link to a further network node, and then upon popping the label from the label stack, (4) forwarding the packet to the further network node by way of the specific link. Various other methods, systems, and apparatuses are also disclosed.

Abstract: In general, techniques described are for providing graceful restart procedures for network devices of label switched paths (LSPs) implemented with label stacks. For example, a restarting network device may include a processor coupled to a memory that executes software configured to: receive a path signaling message including a recovery object that defines a reverse path of the LSP from an egress network device of the LSP to the restarting network device, including at least an upstream label and a downstream label associated with the restarting network device; determine, based on the recovery object, the upstream label and the downstream label associated with the restarting network device; and instantiate a control plane state of the restarting network device based on the recovery object.