Abstract: A fiber-optic communications interface (110) and method of operation that operates with a paired fiber-optic communications interface (112) in a redundant communications termination point (101). The fiber-optic communications interface (110) has a paired card interface (122) that exchanges at least a first subset of status data between a local bearer processor (124) and a paired bearer processor (144) located within a different card cage (112). The local bearer processor (124) processes bearer data channels communicating with a remote site (102) through a remote site fiber-optic line (106). A local data interface (128) exchanges data contained in the bearer data channels between the local bearer processor (124) and a local user data network (114). The local data interface (128) also exchanges at least a second subset of the status data with the paired bearer processor (144) through the local user data network (114).

Abstract: A method and system for MLPPP sequence number synchronization between the active and standby side transmitters is disclosed. The MLPPP sequence number synchronization system includes a method for the standby side to associate transmit frame fragment numbers used by the active side to those generated by the transmitter on the standby side. The association is used to produce an offset which is used to synchronize the active and standby transmitters. The MLPPP sequence number synchronization system is particularly useful for overcoming the drawbacks of high bandwidth signaling between active and standby sides of switches known in the art.

Abstract: A redundancy protection scheme comprises sending a protection packet from the primary network interface to the secondary network interface, the protection packet having a hardware address of the primary network interface as a source address and a hardware address of the secondary network interface as a destination address. The scheme further comprises determining whether the secondary network interface receives the protection packet from the primary network interface, operating the primary and secondary network interface as active and standby network interface in response to the secondary network interface receiving the protection packet, or operating both the primary and secondary network interface as active network interface in response to the secondary network interface not receiving the protection packet, and providing the hardware address of the active secondary network interface to devices coupled thereto.

Abstract: A mechanism provides for communication of “keep-alive” messages from clients to servers in a packet telephony network environment. The servers may be call agents and the clients may be gateways or MGCP-controlled IP phones. A client (e.g., gateway) registers a virtual endpoint. Upon a period of inactivity in which the client does not receive any commands or acknowledgments from an assigned server (e.g., call agent), the client starts to send keep-alive messages periodically to the server. The keep-alive message may include an endpoint identifier that identifies the registered virtual endpoint. If the server fails to respond to the keep-alive messages after a period of time, the client initiates a fallback mechanism from a first call control protocol (e.g., MGCP) to a second call control protocol (e.g., H.323 or SIP), to provide call control handling using a default application.

Abstract: Graceful/hitless restart features from a routing/signaling protocol may be utilized along with synchronization between cluster members in order to provide routing capabilities in a clustering environment. During normal operation, the active cluster member may operate the routing protocol(s) and communicate with the neighboring components using the cluster's address. As the active member learns the routes to the destinations, the routing data may be propagated to the stand-by cluster members across an internal communication mechanism. Configuration information for the routing component may also be propagated to the stand-by cluster members. Upon failure of the active routing component, the standby routing component may be started up such that neighboring routing components located outside of said cluster do not recalculate network topology based on said failure. This allows for failover to occur without affecting neighboring components and unduly burdening the system.

Abstract: According to an aspect of an embodiment, a node apparatus used in at least part of nodes in a network formed by a plurality of nodes coupled in the shape of a ring, comprising: a working node function performing unit for performing functions as a working apparatus that selectively drops a frame destined for a terminal hosted by the node itself among frames transmitted on the ring and adds a frame from the terminal hosted by the node itself to frames transmitted on the ring; a back-up function performing unit for performing functions as a back-up apparatus that lets a frame destined for a terminal hosted by the node itself pass through to an adjacent node and discards a frame from the terminal hosted by the node itself; and a function selection unit for selectively enabling one of the working node function performing unit and the back-up function performing unit.

Abstract: Address Resolution Protocol (ARP) request mirroring can provide a mechanism for synchronizing link-layer adjacency information among network elements. This application can be useful, for example, for internet protocol (IP) routing network elements in a high-availability configuration.

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: A system and method for providing video content to a client system is disclosed. The system includes a server and a computer coupled by a network. The server obtains operating environment information of the computer in response to a request for video content from the computer. The server selects a version of the requested video content for sending based on the obtained operating environment information. The selected video can be received by the computer at the computer's particular connection speed over the network and can be played by the computer using its particular video player. The server sends the selected video to the computer and causes the computer to automatically begin playing the video without requiring any overt interaction by the operator of the computer.

Abstract: One aspect of the invention comprises a method of operating a network for providing services to subscribers, the network including a configuration system comprising: a core system comprising primary and secondary cores, each core being separately capable of controlling operation of the system; at least one cell connected to the core system; and at least one network element connected to the cell, each network element supporting a number of subscribers for provision of the services; the method comprising: operating the configuration system using the primary core; monitoring operation of the primary core for a failure event preventing the primary core from properly controlling operation of the configuration system; on detection of a failure event, transferring control of operation of the configuration system to the secondary core; following correction of the failure event such that the primary core again becomes capable of properly controlling operation of the configuration system, configuring the secondary core

Abstract: A method of providing router redundancy within a distributed network of routers, wherein messages are routed within the network based on virtual router identifiers, involves organizing the routers into one or more redundancy groups; assigning a physical identifier to each router in each of the redundancy groups; assigning one or more virtual identifiers to each redundancy group; selecting one of the routers of a particular redundancy group as a currently active router associated with a particular virtual identifier assigned to that redundancy group; advertising among the distributed network of routers for each redundancy group the physical identifier for the active router and information enabling other routers to determine the virtual identifier with which the currently active router is associated; and forwarding messages destined for a particular virtual router identifier to the currently active router based on the physical identifier of the currently active router.

Abstract: A system is provided for sharing a protection path between at least two protection groups in a network. The system includes at least one working path associated with each of the protection groups, and at least one working maintenance entity group (“WMEG”) monitoring the status of each of the working paths. Each WMEG notifies the protection group associated with the monitored working path of changes in the status of the monitored working path. At least one protection entity group (“PMEG”) monitors the status of the protection path and notifies each of the protection groups of changes in the status of the protection path. Each of the protection groups is switchable to the protection path in response to the receipt of notifications from the WMEG of changes to a non-operational status for the respective working paths associated with each of the protection groups.

Abstract: A method and an apparatus for rapidly resuming, at times of failures, network traffic in a connection-oriented network by using an alternative route pre-computed and stored locally in nodes along an initial route without requiring signaling of upstream nodes or a master server.

Abstract: There is described a method to organize a network, wherein if for a first router set up as the default gateway an inaccessibility of an assigned network element is detected at an interface of the first router a second router is set up as the logical default gateway. In this case a provision is made such that in the course of setting up the second router as the default gateway a check on the interface metric is performed at the first and/or second router and that in consequence of the inaccessibility detected for the interface an adaptation of the interface metric is carried out. The interface metric is propagated for example by way of the routing protocol OSPF and/or EIGRP and/or IS-IS to other routers. When using the method it is possible in a failure scenario with divided Layer-2 networks to avoid an occurrence of “black holes”, in other words gaps in communication.

Abstract: Methods and systems for configuring nodes in a redundant network configuration include identifying a master node from a plurality of nodes in the network by sending a configuration packet to each node. The configuration packet includes an identification number representing the node in the network from which the configuration packet originates, where each node in the network has a unique identification number. At each node in the network, the identification number in the configuration packet is compared to an identification number for that node. In one embodiment, the node whose identification number is greater than the identification number in the configuration packet is designated the master node. A virtual break is created in the network at the location of the master node to prevent a packet from returning to the node from which it originates.

Abstract: A method and system for dynamic protection of virtual links for paths of an optical network in communication with an IP network are disclosed. The method includes establishing two or more paths within the optical network and grouping the paths in a dynamic bundle. The grouping is selected at a control plane level and the bundle of paths are recognized as a single routing adjacency in the IP network so that as long as one or more paths within the bundle is operating, the routing adjacency in the IP network is not affected by changes within the bundle.

Abstract: A method for a network device to access a packet switched network is applied to a system in which the network device accesses the packet switched network by connecting to PEs in an active-standby mode. The method includes: an active PE and a standby PE each sends a fault detection message to the network device through an interface connected to the network device; the active PE sets the state of the interface to “up” and advertises a route to a remote PE if a fault detection response returned by the network device is received through the interface within a preset period; otherwise, the active PE sets the state of the interface to “down”, and withdraws the advertised route; and the standby PE sets the state of the interface to “up” and advertises another route to the remote PE after receiving a fault detection response through the interface connected to the network device.

Abstract: Included are embodiments of a method for recording in an Internet Protocol (IP) environment. At least one embodiment includes receiving data related to a communication, generating a copied version of at least a portion of the received data, and modifying the copied version of the received data. Other embodiments include sending at least a portion of the modified copied version of the received data to a recording device.

Abstract: A network comprises nodes and links. In addition to a default topology there are backup configurations. Each node is inhibited from transferring data between nodes in at least one backup configuration. When a node detects a fault in the reception of data transmitted to a neighbouring node, it switches to a backup configuration in which the neighbouring node is inhibited. In one arrangement a backup configuration has at least one link which is restricted by having a high weighting so that it transmits data to a node only if that node is the final destination node for that data. Additionally, if the neighbouring node is the final destination, and routing of data is still unsuccessful in the backup configuration, the detecting node selects and switches to an alternate backup configuration in which the detecting node is inhibited.

Abstract: A matrix switcher includes a switcher unit having connection switches provided at intersections of input signal lines and output signal lines and a control unit having a main controller and a backup controller. The backup controller operates a Web server program to transfer a setup command to the main controller upon receiving the setup command. The main controller executes: processing of switching a connection relation between the input signal lines and output signal lines in the switcher unit; processing of transferring a switching command to another matrix switcher upon receiving the switching command for another switcher; processing of setting up the matrix switcher upon receiving the setup command for the switcher; and processing of transferring the setup command to another matrix switcher upon receiving the setup command for another switcher.

Abstract: A communications system includes a plurality of operational nodes and a plurality of data distribution systems. A data distribution system operating in an active mode manages exchanges of data between the operational nodes and further operable to periodically transmit go passive messages commanding at least one other of the data distribution systems to operate in a passive mode. A data distribution system operating in the passive mode waits for receipt of one of the go passive messages, continues to operate in the passive mode after receiving one of the go passive messages within a predetermined time out period, and transitions to the active mode after the time out period has expired without receipt of one of the go passive messages.

Abstract: Forwarding liveness, such as the ability of an interface to send and receive packets and forwarding capabilities of the interface, is determined. The determined forwarding liveness may be sent in a single message, allowing forwarding liveness information to be sent more frequently which permits fast detection of failures. The message may also include aggregating liveness information for multiple protocols.

Abstract: A graceful restart is provided in a NSF capable router. When a switchover to a standby controller is required, the standby controller receives replicated link state message headers from an active controller. The standby controller generates a link state request (LSR) message from the link state message headers and transmits the LSRs to neighboring routers. The standby controller receives a link state update that includes the link state messages. By using the LSRs, the standby controller can be quickly synchronized with its neighbors well within the grace period, thereby maintaining adjacency.

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: An expandable exchange apparatus and a backup system thereof are disclosed. The expandable exchange apparatus is applicable to a plurality of terminal devices in a local area network (LAN). The expandable exchange apparatus includes a signal exchange unit having a network connection port and a plurality of terminal connection ports connectable to the terminal devices, a connection unit connecting the LAN to an external network architecture, and a first exchanger connected to the network connection port and the connection unit, the first exchanger selectively connectable to a terminal device that is connected to none of the network connection port and terminal connection ports of the signal exchange unit, wherein, detects whether the network connection port is connected with the terminal device or not, and based on a detected result, correspondingly switches a data transmission path of the network connection port either to the LAN or to the network architecture.

Abstract: This invention provides a tool for reliability evaluation and performance analysis of an IP backbone network by using the network packet loss ratio as the main measurement. A queuing model and algorithm is presented for calculating packet loss at congested interfaces or links. A reliability model is presented for considering network hardware component failures such as router failures, ATM switch failures, and physical link failures. Based on the measurement and models presented, a network reliability and performance (NetRAP) apparatus calculates IP network reliability and performance measurements. The NetRAP apparatus uses the network topology, a traffic matrix, and the reliability parameters of a network as inputs and calculates the network packet loss ratio and sigma score, and provides a list of heavily congested links under non-failure or different single failure conditions.

Abstract: A method of enabling a terminal 1,2 coupled to a GSTN 10 to join an Internet based presence service facilitated by a presence server 6. The method comprises establishing a telephone connection between said terminal 1,2 and an intermediate server 4 via the GSTN 10, as a result of said connection, establishing a proxy entity corresponding to said terminal 1,2 at said intermediate server 4 and registering the proxy entity with the presence server 6 via the Internet, and exchanging presence service messages between the presence server 6 and the proxy entity at the intermediate server 4 via the Internet and between the proxy entity and said terminal 1,2 via the GSTN network 10.

Abstract: A fault-tolerant stack of low cost switches each having only two dual-purpose uplinks is enabled by utilizing a specified topology for connecting the uplinks and implementing a recovery algorithm on each switch.

Abstract: An access control method for a plurality of data communications networks is disclosed that enables a plurality of local nodes (101) to communicate with each other even if the connection between an intermediate node (103) and a global server (105) is momentarily lost. In this method, when the connection to the global server (105) breaks down, the intermediate node (103) temporarily grants access to the local nodes (101) instead of the global server (105) in accordance with a predetermined policy, thus allowing operation of local networks to function normally until connection to the global network (104) is resumed.

Abstract: A system and method for protecting a received data stream. Active receivers and standby receivers are provided, each adaptable to receive a data stream on a traffic channel. Plural data processing units are operatively in communication with the receivers. At least one of the plural DPUs provides a switching signal to the receivers to switch the state of the active receiver to standby and the state of the standby receiver to active as a function of a quality measurement of the received data stream via the traffic channel.

Abstract: A system and method for providing alternate dedicated connections are described. A primary dedicated connection may be configured to connect a first network and a second network, and a second dedicated network-based connection, which may include a point-to-point protocol (PPP)/layer 2 tunneling protocol (L2TP) tunnel, may be configured to automatically connect the first network and the second network when the primary dedicated connection fails.

Abstract: The liveness of routing protocols can be determined using a mechanism to aggregate liveness information for the protocols. The ability of an interface to send and receive packets and the forwarding capability of an interface can also be determined using this mechanism. Since liveness information for multiple protocols, the liveness of interfaces, the forwarding capability of interfaces, or both, may be aggregated in a message, the message can be sent more often than could individual messages for each of the multiple protocols. This allows fast detection of failures, and sending connectivity messages for the individual protocols, such as neighbor “hellos,” to be sent less often.

Abstract: A method and apparatus is directed towards managing fail-over in a network. At least one back-up device is configured to process traffic if a fail-over condition occurs. The back-up device includes a physical interface. A logical interface X associated with the physical interface is monitored to determine if the fail-over condition has occurred. If it is determined that the fail-over condition has occurred on interface X, then the back-up device processes traffic for another logical interface Y, associated with the physical interface. Accordingly, logical interface Y may be unmonitored. According to one embodiment, if it is determined that the fail-over condition has occurred, the back-up device processes traffic for every logical interface associated with the physical interface.

Abstract: A layer 2 switch switching circuit has two layer 2 switches of a redundant configuration and a plurality of cards for sending IP packets to each other through either one of the two layer 2 switches. Each of the two layer 2 switches has a state signal delivery unit for delivering a state signal representing whether the layer 2 switch is in an active state or a standby state. Each of the cards has a card controller for monitoring states of the two layer 2 switches based on state signals sent respectively from the two layer 2 switches, and switching between the two layer 2 switches as a destination of IP packets based on the monitored states.

Abstract: A system comprises a plurality of processing modules, one of which is designated to be the primary processing module and the others are designated to be secondary processing modules. During operation, state is maintained in the primary processing module and at least one of the secondary processing modules. A switchover controller causes outputs from the secondary modules to be discarded. When the switchover controller receives an indication that the primary processing module has failed, it designates one of the secondary processing modules to be the primary processing module. Because the newly designated primary processing module already has current state information at switchover, the module is able to operate with minimal delay.

Abstract: Methods, systems, and devices are provided for controlling the power level of voice signal streams. 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 network access device comprises a first line card, a second line card, and logic. The first line card has a first transceiver coupled to a first subscriber line, and the second line card has a second transceiver coupled to a second subscriber line. The logic is configured to switch communication from the first subscriber line to the second subscriber line in response to a detection of an error condition for communication occurring over the first subscriber line.

Abstract: The disclosed invention relates to a re-synchronization system that operates in a switching arrangement receiving a plurality of incoming data packets. The switching arrangement is made of an active switch card that transmits the incoming data packets and a backup switch card that may be re-activated by an operator after replacement. The re-synchronization system is implemented in each switch card. When the backup switch card is re-activated, both switch cards receive the incoming data packets and the system of the invention allows to re-synchronized both switch cards by controlling the transmission of the incoming data packets out of each switch card until the same data packets are transmitted. The re-synchronization system further comprise storage for storing the incoming data packets and detector for detecting a re-synchronization information among the incoming data packets.

Abstract: A data switchover from a first switching module to a second switching module has no data loss. A graceful code upgrade in a Fibre Channel network, for example, with no data loss can be achieved.

Abstract: An exemplary method for managing a network includes accessing information associated with a managed switch in the network, querying an external data source, and identifying an unmanaged switch connected to the managed switch based on a reply to the query and the accessed information.

Abstract: A system, method and computer readable medium are provided for monitoring functionality of multiple network interfaces and providing fault recovery. The network interfaces are grouped into nodes and a monitoring address is assigned to each of the network interfaces such that the monitoring address for each of the network interfaces is on a different subnet than the monitoring addresses for all of the other network interfaces in the same node as that network interface. According to the method, each of the network interfaces is assigned one or more recovery addresses that each are different than its monitoring address. A monitoring message is periodically sent to each of the network interfaces via the monitoring addresses in order to determine the functionality of the network interfaces. If no monitoring message is received within a predetermined period, a recovery operation is performed for one of the network interfaces using one or more recovery addresses of the one network interface.

Abstract: In one embodiment a switch has active and standby LAYER 2 switch interfaces coupled, respectively, to device interfaces of first and second LAYER 2/LAYER 3 network devices. The active switch interface is configured to forward all egress traffic and accept all ingress traffic and the standby switch interface is configured to forward only IGMP messages and configured to block all ingress traffic.

Abstract: Redundancy for Virtual Private Network (VPN) service with an Ethernet access network is provided by a full-mesh of dedicated pseudowires connected among the network-facing provider edge (n-PE) devices, each of which is associated with the same Ethernet access network. A provider Bridge Protocol Data Unit (BPDU) generated by a provider bridge node in the Ethernet access network and received at an input interface of one n-PE device is relayed (without being processed) to all other n-PEs associated with that access network over the full-mesh of dedicated pseudowires. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: Methods of routing and switching a packet from an incoming link to an outgoing link of a router. In one example, the method includes assigning a destination queue to the packet, determining if the router is implemented in a scaled-down configuration, remapping the destination queue to one or more remapped destination queues, and storing the packet in the one or more remapped destination queues. In one embodiment, the method may also include requesting a packet from the destination queue, translating the request to the remapped destination queue, and transmitting the packet from the remapped destination queue.

Abstract: A communications apparatus includes several functional modules for implementing an application, a pair of switch modules to provide redundant switching capability for transferring frames between the functional modules. Each functional module is connected to each switch module by a frame-based communication link. A redundancy logic unit at each functional module inserts sequence numbers into outgoing frames, replicates the outgoing frames for forwarding to each of said switch modules, and monitors incoming frames from each of the switch modules to select frames for forwarding to an application based on the sequence numbers. In this way, redundancy is maintained at all times, while duplicate frames are eliminated at the receiving module.

Abstract: A method is provided for providing protection of a local area network (LAN) connection that includes providing first and second LAN cards in a multi-service platform. The first and second LAN cards each include at least one port. The first and second LAN cards are coupled to a network edge device through their respective ports to communicate LAN traffic. The method also includes designating the first LAN card as an active card and the second LAN card as an inactive card. The method further includes detecting a network failure associated with the first LAN card. The method further includes protecting LAN traffic communicated between the second LAN card and the LAN by designating the second LAN card as an active card and the first LAN card as an inactive card.

Abstract: The present invention discloses a solution for automated interface switching among routing interfaces. In the solution, a routing daemon can be responsive to operator commands. Routing can be performed in a restricted parallel multi-access interface configuration comprised of a primary and backup interface for conveying routing protocol traffic. The backup interface can be utilized only when the associated primary interface is unavailable. The commands can include a suspend and an activate interface command able to modify the operation of one or more interfaces at the application layer. The suspend interface command can suppress network routing protocol traffic over a specified primary interface and route the traffic over the backup interface. The backup interface can then be designated as the primary interface for which the routing traffic can be conveyed. The activate interface command can activate a suspended interface and can be designated as a backup interface when a primary interface is available.

Abstract: In a networked multi computer environment, with redundant links, network interface cards (NICs) are commonly duplicated and teamed to provide a recovery mechanism when network components fail. Embodiments of the present inventions avoid teaming of pairs of NICs and provide a computing host with redundant network connections for the computing host through a switch that is transparent to the computing host. The computing host itself; that is, its hardware and software, is relieved of the duty of network access redundancy and returned to the simple, simplex networking operating mode. The switch replaces a potentially large number of NICs and the need for computing host network access redundancy management which leads to hardware and software cost reductions and increases the robustness and reliability of the system through redundant network access.

Abstract: A method is provided in one example embodiment and it includes receiving a first plurality of packets from an active stream at an output device and communicating the first plurality of packets to a next destination. The method also includes receiving a second plurality of packets from a standby stream of the output device, the streams are sent by an input device. The method further includes performing a switchover at the output device such that the second plurality of packets is communicated to the next destination and the first plurality of packets is not. The switchover is triggered when a portion of the first plurality of the packets from the active stream is not received during a period of time that is greater than a majority of inter-arrival times of the second plurality of packets on the standby stream.

Abstract: A novel fast reroute (FRR) technique is provided for quickly and efficiently rerouting selected types of network traffic in response to a node or link failure at the edge of a computer network. According to the technique, the network includes first and second edge devices that function as “FRR mates,” such that network traffic originally destined for one FRR mate may be quickly rerouted to the other without having to wait for conventional network convergence. When an edge device receives rerouted packets originally destined for its FRR mate, the device responds by forwarding only those rerouted packets matching the selected traffic types; rerouted packets that do not match the selected traffic types are dropped or otherwise discarded. The first and second edge devices may be statically configured as FRR mates, e.g., by a network administrator, or they may be configured to automatically detect their compatibility as FRR mates.