Abstract: A method for automatically managing a virtual output queuing system in a switching fabric. The method includes detecting if a link is one of a non-operational-link and an operational-link. The link enables communication between a first-switching-unit and a second-switching-unit. If the link is the non-operational-link, the method further includes discarding at least one packet destined for the link. The discarding step further includes either dropping of the at least one packet or scheduling the at least one packet.

Abstract: A method for determining a restoration path corresponding to a primary path for a new service in a mesh network involves (1) generating path costs for candidate restoration paths for the new service, and (2) selecting, for the new service, the restoration path with the lowest path cost, where generating the path cost involves (a) determining, for each link Li in the candidate restoration path, a set B-Li-set of links protected by Li (b) determining, for each link Li, a set I-Li-set of links in the set B-Li-set that are also in the primary path (c) calculating, for each link Li, a link cost based on the set B-Li-set and the set I-Li-set, and (d) calculating the path cost based on a sum of the link costs. In some embodiments, the method includes an efficient scheme for representing, disseminating, storing, and updating sharing information in an OSPF-TE protocol context.

Abstract: Methods and apparatus for enabling line-protected links to be included in path-protected segments of a unidirectional path-switched ring are disclosed. According to one aspect of the present invention, a method for computing a circuit path that includes a primary path between a start node and a destination node as well as an alternate path includes determining the primary path using a routing algorithm. The primary path includes a protectable segment which has a first line-protected link. The method also includes creating the alternate path using the routing algorithm. Creating the alternate path includes creating the alternate path between the start node and the end node with the alternate path arranged to protect at least the protectable segment which includes the first line-protected link. In one embodiment, the alternate path is created including the first line-protected link.

Abstract: A method (600,700) and apparatus (800) are arranged and operate for facilitating call routing between sites in an enterprise connected by a private IP network (130). A range of identifiers (220-223) served by IP PBXs (120-123) in the enterprise may be registered with a SIP registrar (212) of an inter-site router (210). Call requests to a communication unit (350) outside the home site are routed to the SIP registrar. A site identifier associated with the destination IP PBX allows the call to be completed by the SIP Proxy or the IP PBX where the call was received. When no private IP network is available, a roaming CU registers with a cellular proxy in the visited network. Calls are routed by when an HLR (340) associated with the CU obtains the roaming number from the cellular proxy (330) in the visited site. The MSC completes the call to the visited IP PBX using the roaming number and a local SIP registrar 440 forwards the call to the CU.

Abstract: A method and corresponding network interface device for communicating between devices connected to a LAN includes attempting to communicate between the network devices over an initial subset of the network media wires. If the communication fails, a subsequent subset of media wires is selected. The wires of this subsequent subset differ from the wires of the initial subset. If the attempted communication succeeds, the current subset of network media wires is used as the media over which subsequent network data is transmitted. Attempting to communicate over the media may include sending an initialization sequence such as an Ethernet Auto-negotiate sequence. In one embodiment, the network media is implemented as 8 wires of CAT 5 cabling suitable for use with a Gigabit Ethernet. In this embodiment, any subsequent subsets of the network media wires may consist of 4 of the 8 wires over which 100 Mbps Ethernet operation may occur.

Abstract: A system and apparatus for transmitting transit data through a network with first and a second rings coupling two or more nodes. In one aspect, when the first ring is intact and the second ring has a fault between two nodes, transit data may be wrapped from a second, faulted ring to a first, intact ring at an upstream node adjacent to a fault, and transit data may be maintained on the first, intact ring between the upstream node and a downstream node adjacent to the fault. In another aspect, when the system has a fault between any two nodes, the system may preserve host data.

Abstract: A method and apparatus for recovery from faults in a loop network (500) is provided. The loop network (500) has a plurality of ports (520, 530, 532, 534) serially connected with means for bypassing the ports (520, 530, 532, 534) from the loop network (500). A control device (522, 524) is provided with bypass control over at least one of the ports (530, 532, 534). A host means (502) sends a command to the control device (522, 524) at regular intervals and the control device (522, 524) has a counter which restarts a time period at the receipt of each command. If the time period expires, the control device (522, 524) activates the means for bypassing all the ports (530, 532, 534) under its control. The loop network (500) may have two loops (516, 518) with at least some of the ports (520, 530, 532, 534) common to both loops (516, 518).

Abstract: A system and method are described herein that are capable of reducing overhead while keeping the traffic separation characteristics between two routers by establishing and using a generic routing encapsulation (GRE) tunnel directly over a link running a point-to-point protocol (PPP) that connects the two routers. Because, the system and method run GRE sessions directly over the PPP link means there is no need to configure the GRE tunnel over an Internet Protocol (IP) connection which means that outer IP header information does not need to be sent across the link. The elimination of the outer IP header reduces the overhead in the traffic sent between the two routers.

Abstract: A sequence identification number is added to a header in each Generic Framing Procedure (GFP) frame. The byte sequence identification number identifies frames, preventing duplication or loss of exchanges, sequences, and frames. When this feature is enabled, a remote wavelength division multiplexing (WDM) node automatically checks the header to ensure that no duplication or loss occurs. The remote WDM node does not need to buffer data, instead the remote WDM node only needs to keep track of the sequence identification number information. A session identification number is also added to the header information, which allows the WDM node to keep track of which session was under way in the event that all connections between nodes across the WDM network are lost.

Abstract: The invention includes a method and apparatus for providing a distributed control plane for a mobility home agent by enabling multiple home addresses associated with multiple home agents to be assigned to a mobile node contemporaneously. A first home agent assigns a first home address to the mobile node. The first home agent propagates the first home address to the mobile node, which stores the first home address. The first home address is also propagated to a naming server and stored by the naming server for the mobile node. A second home agent, or the first home agent on behalf of the second home agent, assigns a second home address to the mobile node. The first home agent, or second home agent, propagates the second home address to the mobile node, which stores the second home address while continuing to store the first home address.

Abstract: A technique incorporates an efficient means for avoiding micro-loops on a backup path associated with a failed protected link. An intermediate node delays updating a forwarding database (FDB) contained in the intermediate node based on the intermediate node's distance from the failed link. Specifically, intermediate nodes near the failed protected link delay updating their FDBs for a longer period of time than nodes farther away from the failed link. By updating FDBs in this manner, micro-loops may be avoided on the failed link's backup path as nodes on the backup path that are close to the failed link do not update their FDBs ahead of nodes farther away on the backup path.

Abstract: A redundant fieldbus redundant system includes two independent conditioned power modules which automatically detect cable faults, such as short or open circuits on both the host and field sides of the network. The power modules are interfaced directly on one side to the primary and backup H1 cards of the host system, and are directly interfaced on the other side to an automatically terminating network device coupler module which provides connections to field devices. The redundant fieldbus system provides power and communications in a parallel physical configuration between the host system and the field devices irrespective of any single point failure in the network. In case of a fault, the redundant fieldbus system automatically eliminates the faulty section of the network, switches power and communications to the healthy portion of the network and terminates the network for signal integrity.

Abstract: In a label-switched path communications network, each node of the network defines first and second label-switched paths between its first and second output ports and the input ports of downstream nodes. The output ports of each node are monitored. If the first output port is normal, a received packet containing a first label value is switched from any of its input ports to the first output port according to a first relationship between the first label value and the first output port. If the first output port is abnormal, the first label value of the packet is rewritten with a second label value and the packet is switched to the second output port according to a second relationship between the second label value and the second output port. The first and second label values form a pair of companion label values.

Abstract: For upgrading a section of a telecommunication network comprising two nodes, one of the data lines interconnecting the nodes is selected to be a carrier of redundant specimens of information units to be transmitted. An external condition is fulfilled, which is detected by a control unit of the node and causes the control unit to block changes to connections going via the line. In this state, the interface circuits of nodes connected to the selected line are replaced by more powerful ones, and the condition is unfulfilled again. The method is repeated for the other data line.

Abstract: Methods and apparatus for defining an alternate circuit path within a network are described. According to one aspect of the present invention, a device for computing circuit paths between a first node and a second node within a network that has a plurality of elements includes a route generator and a list mechanism. The route generator computes a primary circuit path between the first node and the second node such that the primary circuit path includes a first element. The list mechanism identifies the first element as being inaccessible to an alternate circuit path. Using the list mechanism, the route generator computes an alternate circuit path that does not include the first element identified by the list mechanism. In one embodiment, the first element is a link. In another embodiment, the first element is a node.

Abstract: The present invention discloses a protection-switching apparatus and method in an asynchronous transfer mode (ATM) system with ring topology. In the invention, the ONU detects a trouble, or abnormal states, of an optical path connected with the ONU itself; the ONU performs the protection-switching function by receiving an ATM cell from the opposite direction of the optical path having the trouble; the software unit of the ONU inserts a node identification data (NID) of the ONU to the APS register of the optical path of normal states; and the hardware unit of the ONU generates the APS cell by performing mirroring of the APS register to the VCI area of the APS cell, and transmits the APS cell in the same direction as the direction of the optical path of abnormal states. Therefore, the protection-switching apparatus and method in an ATM system with ring topology of the present invention have the advantage of reducing switching delay time and switching load.

Abstract: Optical transceivers have loopback and pass-through paths for diagnosing transceiver components and optical networks connected to the optical transceiver or for routing data out of the transceiver in a pass-through mode. The loopback paths are selectively configured so that a selected number of the components in the transceiver are included in the loopback path. Where more than one loopback path is present, a network administrator can select which components will be included in a particular test so that, depending on whether a signal is returned on the loopback path as intended, the network administrator can determine which components are operating correctly and which are faulty. The loopbacks can be configured to run on the electrical side of the transceiver from input port to output port or on the optical side from receiver to transmitter. The pass-through paths can be used to connect the transceiver to other devices.

Abstract: Method and apparatus for dynamic provisioning of reliable connections in the presence of multiple failures in optical networks are described. One embodiment is a method for allocation of protection paths after a failure in an optical network. The method comprises, responsive to a failure in an active lightpath, switching traffic on the active lightpath to a protection path; subsequent to the switching, identifying all active lightpaths in the network that no longer have an available protection path; and attempting to allocate a protection path to each of the identified active lightpaths.

Abstract: An optical telecommunication system with automatic channel switching is disclosed. The system is provided with two symmetrical fiber channels and two subsystems. Each subsystem is formed by two 2×2 optical switches that are connected to each end of the primary and secondary channels, including an input light source, an optical receiver, multiple fiber optic power meters, and a control circuit. Data signals are normally sent over the primary channel, while test signals are passed through the secondary channel. The fiber optic power meters are connected to the receiving ends to monitor the power level of transmitted signals over the two channels simultaneously. If a line disconnection is detected, the control circuit automatically initiates a channel switching between the primary channel and secondary channel, and yet optical signals are transmitted and received transparently with high efficiency and reliability.

Abstract: A redundant fieldbus system provides power and communications in a parallel physical configuration between the host system and attached field devices irrespective of any single point failure in the network. In case of a fault, the redundant fieldbus system automatically eliminates the faulty section of the network, switches power and communications to the healthy portion of the network and terminates the network for signal integrity. A device coupler for the system may include a fault detector coupled to an auto-termination circuit that terminates a fieldbus cable when a fault is detected. The device coupler may include fault detection and isolation coupled to each set of spur terminals used to connect field devices to the device coupler. A field device for the system may include circuitry for deselecting a faulty cable while maintaining connection to a healthy cable.

Abstract: A connection in an optical communication system is routed over a sequence of cross-connects and aggregated links comprising multiple links. A different link selection algorithm is used for service provisioning than is used for restoration, i.e., after a cable cut or other failure or incident has made one or paths in the network suddenly unavailable. In particular, a special link selection algorithm called the Interleave algorithm is used for restoration different from the well known Best-Fit algorithm used for provisioning. The Interleave algorithm substantially reduces the probability of glare while maintaining near-optimum capacity utilization.

Abstract: An extension to a connection setup protocol for establishment of a restoration path for a service in a mesh network involves, at a transit node along the restoration path, the steps of (1) receiving a service data structure having an identification of each link and transit node in a primary path for the service, and (2) determining whether to reserve additional protection bandwidth on an outgoing link incident to the transit node using the service data structure, wherein the outgoing link is part of the restoration path. In one or more embodiments, the service data structure includes identification of the service, identification of the outgoing link, and bandwidth of the service. In some cases, the extension involves reserving the additional protection bandwidth on the outgoing link, if the transit node determines that the protection bandwidth is required, based upon knowledge of the protection bandwidth already reserved on the outgoing link.

Abstract: An apparatus has a cross connection circuit, first switching sections located on the input side of the cross connection circuit to switch a presently-used transmission path and a reserve transmission path, and second switching sections located on the output side of the cross connection circuit to switch the presently-used transmission path and the reserve transmission path and comprises slot sections, first selecting section selectively connecting any one of the slot sections to the input side of the first switching section, second selecting section connecting the output side of the first switching section to the input side of the cross connection circuit, third selecting section selectively connecting the output side of the cross connection circuit to the input side of any of the second switching sections, and fourth selecting section connecting the output side of the second switching section to any one of the slot sections.

Abstract: Methods and devices are provided for simulating a direct failure between a network device and an end device. In some implementations, the network device is a gateway of a first network and the end device is a host or a storage device on the first network. In some implementations, the network device includes a linked interface, the administrative and/or operational state of which is determined by the operational state of one or more tracked interfaces. The tracked interfaces may be in the same network device or other network devices, and may be physical or virtual. In some such implementations, when a tracked interface fails, the linked interface will bring down a link between the network device and the end device, thereby causing a switchover to a redundant path. Other implementations involve direct notification of the network device that the link has failed or is about to fail.

Abstract: A switch fabric system comprises a first chassis for receiving a plurality of line cards each having a plurality of ports and at least two switch fabric cards wherein each line card comprises a plurality of link ports for linking the line card with the switch fabric card. Each switch fabric card provides a switching bandwidth. The system comprises a management unit for managing the traffic on the switch fabric cards wherein the management unit removes the traffic from one switch fabric card if the one switch fabric card is to be removed while the other switch fabric card operates and transfers the traffic to the other switch fabric card.

Abstract: Methods, systems, and devices are provided for redundant router set up. One embodiment of a network device having router functionality includes a processor, memory in communication with the processor, and program instructions. The program instructions can be stored in memory and executable on the processor to designate a fail-over virtual router interface for a first physical router on a second physical router based on addressing information obtained via communication between the first physical router and the second physical router.

Abstract: A packet network employs restorable routing with service level guarantees. Restorable routing generates two disjoint paths through a network of nodes interconnected by links for a connection request demand between and ingress-egress node pair. Restorable routing employs minimum interference criteria to generate the two disjoint paths such that two disjoint paths cause little or no interference with demands of future connection requests between different ingress-egress pairs. Restorable routing generates maximum 2-route flows for the network ingress-egress node pairs to determine corresponding sets of 2-critical links. A reduced network is formed, its links are weighted based on criticality indices generated from the sets of 2-critical links, and the relatively optimal two disjoint paths are computed for the connection request. One of the two disjoint paths is selected as an active path for routing data of the connection request, and the other disjoint path is selected as the backup path.

Abstract: There is provided a novel system and method for delivering messages using alternate modes of communication when a primary mode of communication is not available as may happen in emergent circumstances such as those that arise during a terrorist attack causing damage to communications infrastructure.

Abstract: A hitless switching system includes a sending apparatus and a receiving apparatus. The sending apparatus includes: a distributing part for dividing an original signal into a plurality of signals; and a transmitting part for transmitting the divided signals over one or a plurality of transmission lines with redundancy. The receiving apparatus includes: a phase difference detection part for detecting phase differences between signals sent from the sending apparatus; a phase difference absorbing part for absorbing phase differences detected by the phase difference detection part; selectors each of which selects one signal from a plurality of signals; and a restoring part for restoring the original signal from the signals output from the selectors.

Abstract: An Ethernet transmission apparatus having a quick protection and fair attribute as well as a corresponding method are disclosed. The apparatus comprises a sorter, MPLS processing module and a SDH processing module, wherein, the MPLS processing module includes a VC tag packaging unit, a multiplexing unit, a tag managing unit, a scheduler, an MPLS protective unit, an MPLS signaling unit and a Fair algorithm unit. The present invention sorts the Ethernet transactions and labels VC tags by the VC tag packaging unit so as to form a PW LSP. PW LSP with a plurality of identical source and target ends are multiplexed into a tunnel LSP. MPLS signaling unit counts the network nodes that LSP passes by and calculates a protective LSP. MPLS protective unit selects an active LSP or a protective LSP and enters the scheduler for queuing. The FAIR algorithm controls the allotment of the bandwidth so as to secure the fairness of the transactions.

Abstract: In a transmission network including multiplex transmission units A, F, G, D and E, when the line breakage has occurred on the OC-12 transmission path of the direction from unit A to unit F, the unit F detects the signal coming in from the OC-12 path indicative of the line breakage. The unit F inserts the APS bytes which comes in from the unit A into the undefined area of the OC-192 transport overhead which is reserved for the through-transport of APS bytes, and transports it to the unit G. On receiving the through-transport APS bytes, the unit G inserts it intact into the defined area for the APS bytes in the OC-12 transport overhead, and sends it to the unit D. In this manner, protection switching between the units A and D is carried out.

Abstract: A system and method models regional timeout functionality in a discrete event execution environment. A timeout function is initiated associated with an entity upon occurrence of a start condition and terminated or reset upon reaching an end condition. The timeout function is configured to expire after a selected amount of time. Upon expiration of the timeout function, the entity is redirected to a predetermined location for timeout processing.

Abstract: A method and system provide capacity-efficient restoration within an optical fiber communication system. The system includes a plurality of nodes each interconnected by optical fibers. Each optical fiber connection between nodes includes at least three channel groups with different priority levels for restoration switching in response to a connection failure. The system maintains and restores full-capacity communication services by switching at least a portion of the channel groups from a first optical fiber connection to a second optical fiber connection system based on the priority levels assigned to the channel groups. Service reliability is effectively maintained without incurring additional costs for dedicated spare optical fiber equipment by improving idle capacity utilization.

Abstract: An apparatus is described for forwarding data in a data communications network having as components nodes and links therebetween in which nodes obtain a reachability metric between a neighbor node and one or more other nodes in the network and in which a repair path is created between an instigating repair node and a receiving repair node around a failure component therebetween. A propagatable repair address for the receiving repair node is reachable by the repair path notvia the failure component. The apparatus is arranged to treat propagatability of the repair address differently via the failure component than via other components.

Abstract: The present invention relates in general to a method, apparatus, and article of manufacture for providing high-speed digital communications through a communications channel. In one aspect, the present invention employs a variable rate back channel, incorporated within an existing communication that does not increase or adversely impact the transmission rate of data on the communication channel.

Abstract: A method for allowing a node in a wireless communication network to access time slot assignment information on multiple channels includes assigning the node to a first channel associated with a channelized neighborhood having a plurality of nodes. The node communicates in accordance with an access protocol having a common channel frame portion and a channelized frame portion. A plurality of staggered channelized bootstrap slot sections are provided in the channelized frame portion. Each channelized bootstrap slot section is associated with a different channel and offset in time from the other channelized bootstrap slot sections.

Abstract: A method for content storage on behalf of participating content providers begins by having a given content provider identify content for storage. The content provider then uploads the content to a given storage site selected from a set of storage sites. Following upload, the content is replicated from the given storage site to at least one other storage site in the set. Upon request from a given entity, a given storage site from which the given entity may retrieve the content is then identified. The content is then downloaded from the identified given storage site to the given entity. In an illustrative embodiment, the given entity is an edge server of a content delivery network (CDN).

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: A method and a system for automatically managing a virtual output queuing system in a switching fabric. The method comprises detecting if a link is one of a non-operational-link and an operational-link. The link enables communication between a first-switching-unit and a second-switching-unit. If the link is the non-operational-link, the method further comprises discarding at least one packet destined for the link. The discarding step further comprises either dropping of the at least one packet or scheduling the at least one packet.

Abstract: Disclosed herein is a SONET/SDH transmitter provided in a transmission system in which a SONET/SDH network and an IP network are connected with optical LAN-IF. The SONET/SDH transmitter has a redundancy transmission line structure consisting of two transmission lines, a K-packet processing section, and a transmitting section. The K-packet processing section is used for generating a specific byte (SONET K1/K2 byte) of data representing transmission-line switching control information about the transmission lines, packetizing the generated data, and outputting a packet. The transmitting section is used for transmitting the packet to the transmitter provided opposite through the transmission lines. This SONET/SDH transmitter further has a redundancy line switching section.

Abstract: A redundant changeover apparatus causing no frame synchronization loss even upon occurrence of changeover between working system and protection system. In case of an in-apparatus synchronization system, when two input signals which are mutually asynchronous in phase are changed over by a changeover switch, a changeover switch, a clock extractor, a PLL circuit, and a clock changing portion transmit signals with clocks before the changeover being gradually changed to clocks after the changeover. Alternatively, in case of an in-apparatus synchronize system, data are separated from clocks so that the data are once changed to data with reference clocks, and then for the data, clocks before the changeover are gradually changed to clocks after the changeover.

Abstract: Recovery time upon the failure of a link or switching system in an asynchronous data network can be minimized if downstream data switches provide upstream messages indicating to upstream switching system that the downstream traffic arrived in tact and was properly handled. Upon this loss or failure of the upstream status message to an upstream switching system, an upstream switching system can reroute data traffic around a failed link or failed switch with a minimal amount of lost data. The upstream status message is conveyed from a downstream switching system to an upstream switching system via a reverse notification tree data pathway.

Abstract: Commands are shown and described that enable a user to manipulate a call connection for the purpose of maintaining links in a network. The Block command prevents new traffic from being added to an output port of a device in a connection. The Forced Restoration/Release of Forced Restoration command set may be used to service the working channel. The Lockout of Restoration/Release of Lockout commands provide an alternative method of servicing a working connection and preventing unnecessary generation of redundant connections in the network.

Abstract: An optical network includes a plurality of subnets. The subnets each include a plurality of add/drop nodes coupled to the optical ring and operable to passively add and drop traffic to and from the optical ring. The network further includes a plurality of gateway nodes. The gateway nodes are each coupled to the optical ring at a boundary between neighboring subnets and operable to selectively pass and terminate wavelengths between subnets to allow wavelength reuse in the subnets and to provide protection switching.

Abstract: Consistent with a feature of the present invention, protection and working routes are determined by assigning administrative weight values to each route in a network. The administrative weight value of a route can correspond to the physical distance associated with that route. Once the administrative weight values are assigned, that route having the lowest administrative weight value is designated the working route. The protect route is next identified by reassigning administrative weight values to the remaining routes in the network. Those routes that share resources, such as a fiber bundle or conduit, with the working route are assigned high administrative weight values, while those routes independent of the working route are assigned administrative weight values corresponding to the physical distance of each route. That route having the lowest administrative weight value after working route selection is designated the protect route.

Abstract: An optical network includes an optical ring and at least three subnets. Each subnet includes a plurality of add/drop nodes coupled to the optical ring. The add/drop nodes are operable to passively add a first traffic stream in a first direction on the optical ring and a second traffic stream in a second direction on the optical ring. The first traffic stream comprises different content than the second traffic stream, and the first traffic stream and the second traffic stream are transmitted on the same wavelength. The network also includes a plurality of gateway nodes. The gateway nodes are each coupled to the optical ring at a boundary between neighboring subnets and are operable to selectively pass and terminate wavelengths between subnets to allow wavelength reuse in the subnets.

Abstract: Protection switching between primary and secondary paths in a packet-based network involves table entries that are pre-programmed with a primary path, a secondary path, and a value that identifies the primary path, referred to as a primary path identifier (PPI). When table entries are accessed to make forwarding decisions, the PPI is compared to a field that identifies that a particular path is down, referred to as a down path identifier (DPI). If the two fields match, (i.e., PPI=DPI), then the secondary path is selected instead of the primary path as the path on which the traffic should be forwarded.

Abstract: A routing mechanism, service or system operable in a distributed networking environment. One preferred environment is a content delivery network (CDN) wherein the present invention provides improved connectivity back to an origin server, especially for HTTP traffic. In a CDN, edge servers are typically organized into regions, with each region comprising a set of content servers that preferably operate in a peer-to-peer manner and share data across a common backbone such as a local area network (LAN). The inventive routing technique enables an edge server operating within a given CDN region to retrieve content (cacheable, non-cacheable and the like) from an origin server more efficiently by selectively routing through the CDN's own nodes, thereby avoiding network congestion and hot spots.

Abstract: A network is protected against interruption of service while one or more faulty switches or optical fiber transmission lines are repaired or replaced, by an interconnecting configuration of small N×N optical input/output switches, where N is 2 or greater than 2. The switches are configured among protection and working transmission lines. The small number of fibers for each switch improves repair and installation connection reliability and permits configurations that flexibly meet differing requirements. Also the fault is monitored with a fault check signal.

Abstract: A method for restoring traffic in a network. The network includes plural distinct nodes interconnected by plural distinct spans, each span having working links and spare links. Each node has a digital cross-connect switch for making and breaking connections between adjacent spans forming span pairs at a node. Cross-connections between spare links in adjacent spans are made such that sets of successive nodes through which the adjacent spans form span paths form closed paths. A method of finding and construction closed paths is described in which statelets are broadcast through the network. In a preferred method of implementation of the method, the statelet broadcast occurs not in response to a network failure, but across the entire network before any particular span failure and may be carried out during normal network operations as a continual re-configuration of the network.