Abstract: A route for a data unit through a network may be defined based on a number of next hops. Exemplary embodiments described herein may implement a router forwarding table as a chained list of references to next hops. In one implementation, a device includes a forwarding table that includes: a first table configured to store, for each of a plurality of routes for data units in a network, a chain of links to next hops for the routes; and a second table configured to store the next hops. The device also includes a forwarding engine configured to assemble the next hops for the data units based on using the chain of links in the first table to retrieve the next hops in the second table and to forward the data units in the network based on the assembled next hops.

Abstract: In general, techniques are described for packet queuing within ring networks. In accordance with the techniques, a network device of a ring network comprises a memory having a different queue for each order-dependent pair of the network devices. Each pair represents a different order-dependent combination of the network devices that includes an ingress network device that provides an ingress to the ring network and an egress network device that provides an egress from the ring network. The network device further comprises an interface for receiving a packet from a neighboring one of the plurality of network devices and a control unit that, in response to receiving the packet, stores the packet to one of the queues based on which network devices is the ingress and which network device is the egress for the packet. The control unit forwards the stored packet via the ring network according to a scheduling algorithm.

Abstract: A network includes an egress node connected to an ingress node via a network path. The egress node is configured to receive, from the ingress node, a group of packets via the network path, where each packet includes an operations, administration, and management (OAM) field appended to the packet, and where the OAM field stores OAM information. The egress node is further configured to read the OAM information from the packets; analyze the OAM information, associated with one or more of the packets, to determine that a network condition exists on the network path; and notify the ingress node that the network condition exists to permit the ingress node to perform a rerouting operation.

Abstract: An enhanced link state protocol is described for uniquely identifying broadcast networks having overlapping address spaces within a network system. A network device generates first and second link state advertisements (LSAs) in accordance with this link state protocol. The first LSA includes a first identifier dependent on layer 3 addressing information assigned to a physical interface of the first network device that interfaces with a layer 2 communication medium, e.g., an IP subnet address prefix. The second LSA includes a second identifier independent of the layer 3 addressing information assigned to the physical interface of the first network device that interfaces with the layer 2 communication medium, e.g., a unique network identifier associated with a broadcast network. By transmitting this second LSA to a second network device, the network device may uniquely identify broadcast networks having overlapping address spaces.

Abstract: A route for a data unit through a network may be defined based on a number of next hops. Exemplary embodiments described herein may implement a router forwarding table as a chained list of references to next hops. In one implementation, a device includes a forwarding table that includes: a first table configured to store, for each of a plurality of routes for data units in a network, a chain of links to next hops for the routes; and a second table configured to store the next hops. The device also includes a forwarding engine configured to assemble the next hops for the data units based on using the chain of links in the first table to retrieve the next hops in the second table and to forward the data units in the network based on the assembled next hops.

Abstract: A layer 2 transport network, and components thereof, supporting virtual network functionality among customer edge devices. Virtual private network configuration can be accomplished with merely local intervention by preprovisioning extra channel (or circuit) identifiers at each customer edge device and by advertising label base and range information corresponding to a list of channel (or circuit) identifiers.

Abstract: Path determination constraints may be encoded in the form of a program having one or more instructions. Each of instructions may include an operation code, and operands (or pointers to locations where operands are stored). In this way, an extensible, interoperable way for a nodes (e.g., label-switching routers) to communicate constraints within a network is provided. Such constraints may be inserted (e.g., as one or more CONSTRAINT objects) into signaling messages (e.g., a PATH RSVP message). By enabling the signaling of constraints, the determination of constraint-based (label-switched) paths can be distributed among a number of (label-switching) routers or other nodes. Upon receiving a message with constraints (e.g.

Abstract: In general, techniques are described for summarizing label mappings and thereby enabling longest-prefix match within Multi-Protocol Label Switching (MPLS) networks. More specifically, a first router included within a first area of a network comprises a control unit that maintains a label space defining labels available for mapping to a plurality of addresses assigned to network devices within the network. The control unit reserves a contiguous set of the labels of the label space and maps the contiguous set of labels to first area addresses. The first area addresses include those addresses of the plurality of addresses available for assignment to network devices within the first area. The first router also includes an interface card that transmits, to a second router of a second area of the network, an advertisement that advertises a summarized version of the mapping between the contiguous set of labels and the first area addresses.

Abstract: A network device receives a packet with a multicast nexthop identifier, and creates a mask that includes addresses of egress packet forwarding engines, of the network device, to which to provide the packet. The network device divides the mask into two portions, generates two copies of the packet, provides a first portion of the mask in a first copy of the packet, and provides a second portion of the mask in a second copy of the packet. The network device also forwards the first copy of the packet to an address of a first egress packet forwarding engine provided in the first portion of the mask, and forwards the second copy of the packet to an address of a second egress packet forwarding engine provided in the second portion of the mask.

Abstract: A network device includes a processor that executes a software module above an operating system of a network device, wherein the software module is configured to create a set of forwarding structures for use in forwarding network traffic with the network device without regard to limitations of an underlying architecture of the forwarding plane. The network device also includes a forwarding structure control module operative within or below the operating system of the network device, wherein the forwarding structure control module is configured to create a set of derived forwarding structures based on the set of forwarding structures provided by the software module for installation in the forwarding information of the forwarding plane. The derived set of forwarding structures is created in accordance with the limitations of the underlying architecture of the forwarding plane.

Abstract: Techniques are described for automatically selecting virtual private network (VPN) site-IDs for each customer site within a VPN established over a network. The techniques described herein enable a network router within a VPN to automatically allocate unique site-IDs for each customer site included in the VPN in a dense manner. In some cases, the VPNs may comprise virtual private local area network (LAN) service (VPLS) domains that transmit layer two (L2) traffic between customer sites, i.e., VPLS sites, via the network. For example, a network service provider may configure a network device, such as a router, to belong to one or more VPNs. When a customer site within one of the VPNs connects to the router, the router configures the customer site on the router. The router then automatically selects a site-ID for the customer site configured on the router.

Abstract: A method performed by a network device may include assembling a multiprotocol label switching (MPLS) echo request, the echo request including an instruction for a transit node to forward the echo request via a bypass path associated with the transit node, and an instruction for an egress node to send an echo reply indicating that the echo request was received on the bypass path. The method may also include sending the MPLS echo request over a functioning label switched path (LSP).

Abstract: When a node has to restart its control component, or a (e.g., label-switched path signaling) part of its control component, if that node can preserve its forwarding information across the restart, the effects of such restarts on label switched path(s) include the restarting node are minimized. A node's ability to preserve forwarding information across a control component (part) restart is advertised. In the event of a restart, stale forwarding information can be used for a limited time before. The restarting node can use its forwarding information, as well as received label-path advertisements, to determine which of its labels should be associated with the path, for advertisement to its peers.

Abstract: Path determination constraints may be encoded in the form of a program having one or more instructions. Each of instructions may include an operation code, and operands (or pointers to locations where operands are stored). In this way, an extensible, interoperable way for a nodes (e.g., label-switching routers) to communicate constraints within a network is provided. Such constraints may be inserted (e.g., as one or more CONSTRAINT objects) into signaling messages (e.g., a PATH RSVP message). By enabling the signaling of constraints, the determination of constraint-based (label-switched) paths can be distributed among a number of (label-switching) routers or other nodes. Upon receiving a message with constraints (e.g.

Abstract: In general, techniques are described that facilitate application of service within MPLS networks. More specifically, a router comprises a forwarding plane, a service plane and a routing engine. The routing engine maintains data defining an association between a handle identifying a property common to a plurality of packets of a particular context and one or more MPLS labels associated with these packets. The routing engine automatically generates and installs a filter to identify these packets within both the forwarding and service planes. The forwarding plane applies the filter to incoming packets to determine whether each of the incoming packets includes a label matching any of the labels of the filter and forwards the incoming packets to the service plane upon a match. The service card selects one or more services identified by the filter and applies the selected one or more services to the incoming packet.

Abstract: A network device includes a memory, a routing engine and a forwarding engine. The memory stores a forwarding table and the routing engine constructs a first composite next hop that includes multiple next hops, where each of the multiple next hops represents an action to be taken on a data unit as it transits the network device or represents another composite next hop, and where the first composite next hop specifies a function to be performed on the plurality of next hops. The routing engine further stores the composite next hop in an entry of the forwarding table. The forwarding engine retrieves the composite next hop from the forwarding table, and forwards a data unit towards one or more network destinations based on the composite next hop.

Abstract: The label distribution protocol (LDP) is extended to set up a point to multi-point (P2MP) label switched path (LSP) across a computer network from a source network device to one or more destination network devices. LDP is extended to create a P2MP label map message containing a label and a P2MP forwarding equivalence class (FEC) element having a root node address and an identifier. The P2MP FEC element may, for example, associate an address of the root node of the P2MP LSP with an opaque identifier. The P2MP FEC element uniquely identifies the P2MP LSP. The P2MP FEC element may be advertised with a label in a P2MP label map message. A source network device or the destination network devices may initiate setup and teardown of the P2MP LSP. The P2MP label map messages may be propagated from the destination network devices to the source network device.

Abstract: In general, principles of the invention relate to techniques for detecting data plane failures in Multi-Protocol Label Switching (MPLS) Label-Switched Paths (LSPs) that may be tunneled over one or more other LSPs. More specifically, the techniques described herein allow for testing connectivity of an LSP that is tunneled through at least one other LSP, and testing connectivity of an inter-autonomous system LSP. For example, a method comprises providing, with an intermediate label-switching router (LSR) of an LSP, instructions to an ingress LSR of the LSP to modify a forwarding equivalence class (FEC) stack of MPLS echo request packets. The intermediate LSR may provide the instructions within an MPLS echo reply packet.

Abstract: A method performed by a network device may include assembling a multiprotocol label switching (MPLS) echo request, the echo request including an instruction for a transit node to forward the echo request via a bypass path associated with the transit node, and an instruction for an egress node to send an echo reply indicating that the echo request was received on the bypass path. The method may also include sending the MPLS echo request over a functioning label switched path (LSP).

Abstract: Techniques are described for providing routing scalability within a protocol such as a label distribution protocol. A method comprises receiving a label mapping message at an ingress router for establishing a label switched path (LSP) that identifies within a first portion a first label to be used for forwarding network traffic to an intermediate router of the LSP, and identifies within a separate portion a second label to be used for forwarding network traffic to an egress router of the LSP. The method further comprises parsing the first and separate portions, installing first forwarding state at the ingress router identifying the first label for forwarding network traffic to the intermediate router, and installing second forwarding state at the ingress router identifying a two-label stack comprising the first label as an outer label and the second label as an inner label for forwarding network traffic to the egress router.