Abstract: In one embodiment, a source transmits one or more data packets to a destination over a primary pseudowire (PW). When a device on the primary PW detects a downstream failure of the primary PW, and in response to receiving one or more data packets from a source from the failed primary PW, the device adds a loopback packet identifier to the one or more received data packets, and returns the one or more data packets with the loopback packet identifier to the source upstream on the primary PW. Accordingly, in response to receiving the data packet returned with a loopback packet identifier from the primary PW (in response to the downstream failure), the source retransmits the one or more data packets to the destination over a backup PW.

Abstract: In one embodiment, a maintenance intermediate point (MIP) receives a packet traveling along a multi-protocol label switching (MPLS) label switched path (LSP) that extends from a first maintenance end point (MEP) to a second MEP. The receiving MIP decrements a time-to-live (TTL) value in a header of the packet. In response the TTL value in the header of the packet equaling a particular value, the receiving MIP examines an associated channel header (ACH) field in an operations, administration, and maintenance (OAM) message stored in a payload of the packet, and determines a particular OAM function to perform based on a code in the ACH field. The receiving MIP performs the particular OAM function.

Abstract: A technique dynamically restores original attributes of a Traffic Engineering Label Switched Path (TE-LSP) that are provided in a source domain for a destination domain when traversing one or more intermediate domains that may translate the TE-LSP attributes in a computer network. According to the novel technique, a head-end node requests an interdomain TE-LSP having one or more original TE-LSP attributes (e.g., priority, bandwidth, etc.) using a signaling exchange. The head-end node may also request restoration of the original TE-LSP attributes upon entrance into the destination domain. Intermediate domains (e.g., border routers of the domains) receiving the request may translate the original TE-LSP attributes into corresponding intermediate domain TE-LSP attributes. When the request reaches the destination domain, the intermediate domain TE-LSP attributes of the requested TE-LSP are restored into the original TE-LSP attributes.

Abstract: In one embodiment, a method includes receiving at a node in a first network, information identifying a spare interface between a first network device in the first network and a second network device in a second network, and using the spare interface to create a path in the first network if the spare interface is compatible. The spare interface information includes connectivity and compatibility information.

Abstract: An example method includes detecting a failure at a first network element, the failure is associated with a link between the first network element and a second network element. The method also includes generating a list of network elements to be notified based on the failure, the second network element is included on the list. The method further includes generating an alarm indication signal (AIS) message, the AIS message identifies a plurality of tunnels affected by the failure. The AIS message is communicated to the second network element. In more detailed embodiments, each link between the first network element and the second network element includes a globally unique link identifier, which includes an associated autonomous system number. The globally unique link identifier can represent a string to be associated with the plurality of tunnels, the globally unique link identifier includes a source address and a destination address.

Abstract: Optimal automated exploration of hierarchical Multiprotocol Label Switching Label Switch Paths (MPLS LSPs) is disclosed. A path verification message (PVM) is transmitted from an initial router. Each label in the PVM's label stack corresponds to a hierarchy layer and is associated with a time-to-live (TTL) field. The TTL field for the label of a current layer is set so the PVM travels one hop from the initial router. In response, a reply message indicating that the PVM reached its destination is received.

Abstract: A technique for multiple path forwarding of label-switched data traffic in a communication network across multiple paths such that traffic associated with a particular label-switched path (LSP) is forwarded on the same path in the network. An incoming label associated with a packet is used to select an Equal Cost Multiple Path (ECMP) technique that is used to identify an interface among a plurality of interfaces on which the packet may be forwarded. An incoming label associated with the packet is used to identify an outgoing label for the packet as well as the plurality of interfaces on which the packet may be forwarded. A label in the packet's label stack is hashed to produce a hash value. The hash value is then used to identify an interface from the plurality of interfaces on which the packet is forwarded. The outgoing label is placed in the packet and the packet is forwarded on the identified interface.

Abstract: In one embodiment, a method includes generating an aggregated pseudowire status message at a first network device in a Multi-Protocol Label Switching (MPLS) network, transmitting the aggregated pseudowire status message to a second network device on a Label Switched Path (LSP) extending between the first and second network devices in the MPLS network, and establishing at the first network device, an aggregated pseudowire status session with the second network device upon receiving a response to the aggregated pseudowire status message on the LSP. The aggregated pseudowire status message configured to verify a current status of pseudowires on the LSP. An apparatus is also disclosed.

Abstract: In one embodiment, a router initiates reroutes of one or more tunnels at the router as part of optimization of a plurality of tunnels in a computer network, and stores an original state of the one or more tunnels at the router prior to the optimization. By detecting whether path computation element (PCE) failure occurs prior to completion of the optimization, the router may revert to the original state of the one or more tunnels in response to PCE failure prior to completion of the optimization.

Abstract: In one embodiment, a path computation element (PCE) in a computer network receives one or more path computation requests (PCReqs), and records a time of each PCReq and the corresponding requested bandwidth. Based on this information, the PCE may determine a traffic profile of the computer network, and may augment a traffic engineering database (TED) with requested bandwidth according to time based on the traffic profile. As such, prior to a particular time, the PCE may determine placement of tunnels within the traffic profile for the particular time.

Abstract: In one embodiment, a method includes generating an aggregated pseudowire status message at a first network device in a Multi-Protocol Label Switching (MPLS) network, transmitting the aggregated pseudowire status message to a second network device on a Label Switched Path (LSP) extending between the first and second network devices in the MPLS network, and establishing at the first network device, an aggregated pseudowire status session with the second network device upon receiving a response to the aggregated pseudowire status message on the LSP. The aggregated pseudowire status message configured to verify a current status of pseudowires on the LSP. An apparatus is also disclosed.

Abstract: A technique may improve LDP-IGP synchronization in a MPLS network when an interface of a router coupled to a communications link along a shortest path between a source router and a destination router becomes newly active. Specifically, an IGP adjacency may be held down over the newly active link while a LDP adjacency is established over the link. The router may inject a temporary, non-redistributable route having a large administrative weight into its routing table utilizing addresses learned during establishment of the LDP adjacency. The injected route ensures that there is a reachable route to a peer router so that LDP may converge. After LDP has converged and all needed label bindings have been distributed in the MPLS network utilizing the injected route, IGP executing on the router may advertise a normal cost metric for the link associated with the newly active interface, and IGP convergence may be completed.

Abstract: In one embodiment, an initiating maintenance end point (MEP) may transmit a lock message to lock a circuit traversing one or more maintenance intermediate points (MIPs) between the initiating MEP and an end MEP. The initiating MEP may then transmit an in-band packet containing a loopback request to a particular MIP along the circuit using a particular time-to-live (TTL) value in the packet to reach the particular MIP. Upon receiving the packet at the particular MIP, and in response to determining that the TTL has expired, the particular MIP inspects the packet to discover the loopback request, and correspondingly operates in a loopback mode.

Abstract: In one embodiment, a connection verification (CV) message is initiated from an initiating maintenance end point (MEP) for an MPLS LSP, the CV message carried in a packet having a time-to-live (TTL) value of 1. Each maintenance intermediate point (MIP) along the MPLS LSP receives the packet and decrements the TTL, and in response to determining that the TTL equals 0, examines a payload of the packet to determine that the packet carries the CV message. The MIP may then append its MIP ID to a route record field of the payload having any previous MIP IDs of upstream MIPs, and forwards the CV message downstream along the MPLS LSP in a packet having a TTL value of 1. The end MEP receives the CV message, and sends a CV reply having the route record field with MIP IDs and an end MEP ID to the initiating MEP.

Abstract: Improved detection of specific BFD LSP path failures is herein disclosed. The improved detection described herein allow for faster fault isolation of a failure along a LSP path, which in turn may allow for faster repair of the failure. When opening a BFD session with a LSP egress node, the LSP ingress node provides the LSP egress node a path descriptor along with the BFD Discriminator. If a BFD failure is detected at the LSP egress node, the LSP egress node can signal an alarm that includes a full description of the path.

Abstract: Improved connectivity verification is disclosed. A root in a point-to-multipoint network can establish parameters for a connectivity-verification session with each endpoint in the network. The root then sends verification-request messages to each endpoint in accordance with the parameters. Each endpoint signals an alarm (e.g., sends a reply to the root) if the verification-request messages are not received at the endpoint in accordance with the established parameters. In this manner, endpoints send verification-reply messages to the root much less frequently, greatly reducing the congestion at the root and greatly reducing the chance that the root gets congested or even overwhelmed when the network includes large numbers of endpoints.

Abstract: Optimal automated exploration of hierarchical MPLS LSPs is disclosed. A path verification message (PVM) is transmitted from an initial router. Each label in the PVM's label stack corresponds to a hierarchy layer and is associated with a time-to-live (TTL) field. The TTL field for the label of a current layer is set so the PVM travels one hop from the initial router. In response, a reply message indicating that the PVM reached its destination is received. These steps are then repeated. For each successive PVM transmitted, the TTL field associated with a label corresponding to the current hierarchy layer is incremented. For any reply message including information describing a non-current layer, modify the next PVM's label stack and increment the TTL field of the label for the described different layer; any other TTL fields are unchanged. If any received reply message indicates a destination router was reached, the process terminates.

Abstract: An example method includes detecting a failure at a first network element, the failure is associated with a link between the first network element and a second network element. The method also includes generating a list of network elements to be notified based on the failure, the second network element is included on the list. The method further includes generating an alarm indication signal (AIS) message, the AIS message identifies a plurality of tunnels affected by the failure. The AIS message is communicated to the second network element. In more detailed embodiments, each link between the first network element and the second network element includes a globally unique link identifier, which includes an associated autonomous system number. The globally unique link identifier can represent a string to be associated with the plurality of tunnels, the globally unique link identifier includes a source address and a destination address.

Abstract: In one embodiment, a protected switching provider edge (S-PE) and a backup S-PE may be operated, where the protected S-PE has at least one multi-segment pseudowire (MS-PW) and is between a first and second provider edge (PE) on the MS-PW. To protect the protected S-PE, the first and second PE may be informed of the backup S-PE and a backup label to reach the second and first PE, respectively, via the backup S-PE to remain on the MS-PW. Upon detecting loss of connectivity with the protected S-PE, the first and/or second PE may forward packets of the MS-PW to the backup S-PE with the corresponding backup label to reach the second or first PE, respectively, on the MS-PW.

Abstract: In one embodiment, a method includes generating an aggregated pseudowire status message at a first network device in a Multi-Protocol Label Switching (MPLS) network, transmitting the aggregated pseudowire status message to a second network device on a Label Switched Path (LSP) extending between the first and second network devices in the MPLS network, and establishing at the first network device, an aggregated pseudowire status session with the second network device upon receiving a response to the aggregated pseudowire status message on the LSP. The aggregated pseudowire status message configured to verify a current status of pseudowires on the LSP. An apparatus is also disclosed.