Abstract: A method of connecting a line concentrator to other line concentrators in a switching system, wherein a switching unit accommodates the line concentrator is provided. The method includes the steps of analyzing a call received by the switching unit through the line concentrator, and connecting lines that are accommodated by the line concentrator and are connected to the other line concentrators without connecting through the switching unit when the call is detected to be made between the line concentrator and the other line concentrators. Thus, a call can be made to a specific dial number without connecting through the switching unit provided in the switching system. Additionally, a call can also be made by use of another switching unit when a communication path between the switching unit and the line concentrator is overcrowded.

Abstract: The present invention provides for efficient and reliable IP addressing in redundant telephony modules where an active one of the redundant modules must communicate using a common IP address. An addressing methodology is provided wherein an active module in a node assumes and uses an active IP address for the node. The inactive module may assume and use an inactive IP address for communication directed to the inactive module within the node.

Abstract: A router comprising a priority level distinguishing means for distinguishing the priority level of a packet by referring to the information contained in the header of the packet, a routing table where an output path comprising one or more output lines can be mapped to each level of priority, an output path determining unit that searches the routing table and determines an output path to be used for sending out packets, and a preferential delivery controller that executes delivery control in accordance with the priority level for each output line corresponding to the output path. In response to a fault state in a preferred output line, the router can reroute high priority packets over an alternative output line while maintaining priority. The router may also calculate a distribution ratio to determine the optimal load for each output line for a given packet priority.

Abstract: A working router is coupled to a SONET add-drop multiplexor (ADM) through a working line and a protection router is coupled to the ADM through a protection line. The routers are coupled to each other by a separate side-band connection and comprise a virtual router from the perspective of the neighboring router, which communicates with the virtual router over the SONET network using the Point-to-Point Protocol (PPP). The protection router transmits a heartbeat message to the working router over the side-band connection. If the protection router does not receive a response thereto, it initiates a line switch within the add-drop multiplexor. Once the line switch is complete, the protection router exchanges datagrams with the neighboring router, via the ADM and SONET ring to which the ADM is coupled. The protection router establishes a PPP connection between itself and the neighboring router device coupled to the SONET ring, utilizing the Link Control Protocol (LCP).

Abstract: A method for protecting the flows of traffic against, and for restoring them from, a failure in a multifunctional, hybrid broadband access-and-transport network system includes the provisioning of at least two Virtual Flows (“VFs”) of traffic between each pair of ingress and egress (“I/E”) nodes in the system. The at least two VFs are provisioned such that each takes a different physical path from the other. The VFs taking the same physical path are then respectively grouped into two “Path Protection Groups” (“PPGs”). Each of the PPGs has a dedicated “Management Control Flow” (“MCF”) provisioned within it that is carried in the at least one VF contained therein. The detection of a fault in the traffic in an “active” PPG results in the generation of a protection switching signal (“PSS”) being generated and sent by the nodes detecting the fault along the MCF of the affected PPG to the relevant “protection switching entities” (“PSEs”), i.e.

Abstract: A method is provided to allocate bandwidth from a first node to a second node in a optical network. The method begins by accepting a request from an end-user, who requests a virtual path between the first node and the second node. The first and second nodes are ones of a number of such nodes. Each one of the nodes is coupled to at least one other node by at least one of a number of optical links. The nodes and links form the optical network. The virtual path has a bandwidth requirement associated therewith. Next, the service provider determines an amount of bandwidth available between the first and the second nodes. The service provider then allocates at least a portion of the amount of bandwidth available between the first and second nodes equal to the bandwidth requirement, so long as the bandwidth requirement is not greater than the amount of bandwidth available between the first and second nodes.

Abstract: The load of each gateway for connecting the mobile network and a predetermined communication network is distributed. In each gateway, data stored in a predetermined information server connected to the communication network is obtained in response to a request from the mobile terminal; the format of the obtained data is converted according to restrictions on resources of the mobile terminal; load imposed on predetermined processes including the data obtainment and the format conversion is measured; and load data indicating information relating to the measured load is sent. In a mobile communication control apparatus for selecting one of the gateways, the load data communicated from each gateway is stored, and when receiving a request for obtaining the data stored in the information server from the mobile terminal, the apparatus selects a gateway based on the load data.

Abstract: A network that is architectured to distributively be responsible for remedying failures achieves advantageous operation. This is accomplished by algorithmically and distributively assigning the responsibility for recovery from all failures to different network nodes and by re-routing traffic at the failed point though network elements in close topological proximity to the failed point. Each node maintains an awareness of the spare resources in its neighborhood and pre-plans re-route plans for each of the failures for which it is responsible. It maintains the created re-route plans and, upon detection of a failure, transmits a re-route plan to particular nodes that participate in the re-routing recovery planned for such a failure. Alternatively, it transmits re-route plans to the nodes that need them, and upon detection of a failure, the network node broadcasts an ID of the re-route plan that needs to be executed.

Abstract: A backup gateway apparatus is provided in a home network, connected parallel to a gateway apparatus. The backup gateway apparatus detects when the gateway apparatus is malfunctioning. During the period when the gateway apparatus is malfunctioning, the backup gateway apparatus performs a partial backup function to maintain communication paths with outside lines, on behalf of the gateway apparatus.

Abstract: A method for recovering from malfunctions in a primary agent module of a modular network device. The primary agent module is installed in a modular network device having a number of network interface modules housed in a chassis. A backup agent module is installed in the chassis when the modular network device is powered on. The backup agent module determines if the primary agent module has been installed when three dedicated signals of the primary agent module are asserted. The network device then synchronizes all configuration information of the network interface modules from the primary to the backup agent module. The backup agent module detects that the primary agent module has failed if it cannot receive a message sent from the primary agent module within a predetermined time interval. As a result, the modular network device is rebooted and the backup agent module becomes the primary agent module.

Abstract: A cell switch node (20) has a first switch plane (22); a second switch plane (24); a sender switch port interface unit (26S); and a receiver switch port interface unit (26R). The sender switch port interface unit sends maintenance cells to the receiver switch port interface unit via the first switch plane and the second switch plane. The maintenance cells are applied to the first switch plane and the second switch plane in a predetermined sequence. The receiver switch port interface unit detects an erroneous switch plane when the maintenance cells from the sender switch port interface unit do not arrive in the predetermined sequence.

Abstract: Network elements such as digital crossconnects are provided with a 1:1 redundancy of, among other things, the switching matrix in order to maintain their functionality in the event of a hardware failure. Against disasters such as fires, explosions, or floods in which all equipment in a room is destroyed, the redundancy used in prior-art network elements can afford no protection. To remedy this, the two switching matrices (21, 22), which are present anyhow, are installed in separate rooms (31, 32), i.e., a single network element is divided between two rooms. To this end, the interface modules (23, 24) are divided into two groups, and each of the groups is assigned to a respective one of the switching matrices. A respective one of the switching matrices and a respective one of the groups of interface modules are arranged in, e.g.

Abstract: An efficient method and system for maintaining the data connectivity with the MLPPP peer in the event of failure of the processor running the Active MLPPP protocol engine, without requiring expensive, per-packet update messages between the redundant nodes is provided. Grouping of information from multiple bundles is implemented to implement multi-bundle redundancy.

Abstract: A method of providing network services is described. The network includes a number of nodes, each one of which is coupled to at least one other of the nodes by at least one of a number of optical links. The network is preferably capable of supporting a number of virtual circuits. The method begins with the receiving of a request for a virtual circuit between a first node and a second node of the network. Preferably, the request specifies a quality of service of the virtual circuit. Next, the availability of network resources for supporting a virtual circuit at the requested quality of service is determined. Assuming sufficient network resources are available for support of the virtual circuit, the request is then serviced by provisioning (and maintaining) the requested virtual circuit. Servicing the request preferably includes actions such as provisioning, maintaining, and restoring the virtual circuit, using the requested parameters.

Abstract: Instead of alternatively utilizing only one fabric or the other fabric of a redundant pair, both fabrics simultaneously transmit duplicate information, such that each packet forwarding module (PFM) receives the output of both fabrics simultaneously. In real time, an internal optics module (IOM) analyzes each information chunk coming out of a working zero switch fabric; simultaneously examines a parallel output of a working one duplicate switch fabric; and compares on a chunk-by-chunk basis the validity of each and every chunk from both switch fabrics. The IOM does this by examining forward error correction (FEC) check symbols encapsulated into each chunk. FEC check symbols allow correcting a predetermined number of bit errors within a chunk. If the chunk cannot be corrected, then the IOM provides indication to all PFMs downstream that the chunk is defective. Under such conditions, the PFMs select a chunk from the non-defective switch fabric.

Abstract: A router includes multiple routing engines. If the active routing engine fails, a backup one of the routing engines detects the failure and assumes the role of active routing engine. A redundancy controller circuit, connected to the multiple routing engines, facilitates the selection and switching of the routing engines. Portions of the packet forwarding engine, in addition to the routing engine, may be redundantly implemented. The active routing engine controls the selection of the redundant portion of the packet forwarding engine.

Abstract: To detect network faults or congestion of traffic at an interface of a gateway system for connecting an IP network and a telephone network on the side of the IP network and to allow the IP network to control alternative routing at the telephone network, network faults and congestion of traffic on the side of the IP network are monitored by the gateway system having an interface function between the telephone network and the IP network. When a network fault or congestion of traffic is detected, the gateway system notifies the telephone network upstream thereof of the disabled line and instructs the same to perform alternative routing, which makes it possible to prevent the occurrence of a situation in which the quality of communication at the interface between the telephone network and IP network can not be maintained.

Abstract: A redundant LAN system is characterized in that with a redundant LAN system which includes sub-LAN systems with redundancy incorporated by an active and a stand-by mode, a plurality of the sub-LAN systems being connected to the same LAN segment, immediately after a sub-LAN system on an active line is switched, ARP packets for updating ARP cache tables of the redundant LAN system from MAC addresses of a previously active line to MAC addresses of a new active line, are transmitted from a sub-LAN system on the new active line to all communication devices connected to the same LAN segment as the sub-LAN system on the new active line.

Abstract: A method and apparatus selecting between primary switching fabric in an asynchronous transfer mode (ATM) network includes a Tap Mux controller that monitors the signals being transmitted to each of four fabric access devices. As each of the fabric access devices receives nine communication lines, the Tap Mux controller monitors a total for 36 communication lines on the primary switching fabric. Because the switching fabric is completely redundant, however, the Tap Mux controller also monitors a total of 36 communication lines on the protection switching fabric. The Tap Mux controller, therefore, includes logic that defines 72 state machines that each monitor one of the 72 lines. Each state machine, in the described embodiment, initiates a defined length time window and counts errors therein.

Abstract: In accordance with methods and systems consistent with the present invention, an improved failure recovery system is provided that, upon detecting a failure, generates new routings for the network which (1) avoid the failure and (2) avoid deadlock. In this manner, after a failure is detected, the network remains as operational as possible while still avoiding deadlock. Thus, by using the improved failure recovery system, a network failure has a much less severe impact on the network than in conventional systems.

Abstract: A data network may comprise routers for transmitting data between locations in the network via alternative routes. A network gateway or server may normally send data packets to a particular default router but, for network communication recovery, the gateway needs to select a new default route if the first goes down. The recovery method of this invention comprises storing information indicative of respective ones of a plurality of said alternative routes; accessing the stored information to identify a first of said routes; directing data to the router means for the data to be transmitted to the said another location via the first route; sensing failure of said transmission and, in the event of such failure, accessing said stored information to identify a second of said alternative routes; and directing data to the router means for the data to be transmitted to the said another location via the second route.

Abstract: A method, apparatus and article of manufacture for routing a data packet in a fault tolerant manner. A data packet is received from an incoming data channel and is transferred to a switching engine (SE) through an access processor engine (APE). A route for the data packet is generated using a central processor resource (CPR). The data packet is transferred from the SE to an outgoing trunk physical module (TP) using the route.

Abstract: A method and apparatus for transferring data between a handheld device and a network over a wireless communications link. A datapool manager breaks files into virtual blocks and adds the virtual blocks to a datapool. A communications manager converts the virtual blocks into transportation packets and controls the transfer of the transportation packets between the handheld device and the network. After a transportation packet is transferred, an acknowledgment is returned indicating that the transfer was successful. If the transfer of a file is interrupted, then, upon reestablishing the wireless link, only those transportation packets for which an acknowledgment has not been returned are transferred. To properly reconstruct the file, a pointer indicates the location of each transportation packet in the file. Furthermore, to enable the use of a partially transferred file, a table of information is maintained indicating the validity of the partially transferred file.

Abstract: Methods and apparatus for providing a device for forwarding packets in a network are disclosed. A first router and a second router having a shared set of interfaces are provided, enabling the first router and the second router to share forwarding data for forwarding packets on the shared set of interfaces.

Abstract: A system and methods are shown for providing packet data serving node (PDSN) redundancy. One exemplary method includes providing an access node with a plurality of packet data serving nodes and at least one system manager, establishing an N to 1 redundancy of active to standby PDSNs. Upon establishing a communications session with a mobile node, each active PDSN provides state updates to the standby PDSN including only non-recoverable data. Upon failure of any active PDSN, the standby PDSN reassigned as an active PDSN replacing the failed unit and assuming the communications session with the mobile node. The remaining active PDSNs are notified of the reassignment and transmission of updated state data is discontinued.

Abstract: A routing system provides for transparent routing system failover by checkpointing route prefixes during normal operation by maintaining a route prefix table. After failure of a primary routing processor, routing with peer routing systems is synchronized through the use of this prefix table. The prefix table is managed by the primary routing processor and is accessible by a backup routing processor at least after failure of the primary routing processor. Upon the detection of a failure, a backup routing processor solicits routes from peer routing systems in response to the failure and generates a backup routing database from the routes received from peer routing systems. The backup routing processor also compares prefixes of routes in the backup routing database with prefixes in the prefix table, and sends route withdraw messages to the peer routing systems for routes having prefixes listed in the prefix table and not identified in the backup routing database.

Abstract: A communications system and method for transmitting data to a mobile platform is provided. The communications system comprises a forward link assignment manager in communication with a route server and a router, wherein the router selects from paths of forward link equipment chains to transmit data to the mobile platform. Generally, the forward link assignment manager assigns a cost to the path of each chain such that the more available the chain, the lower its cost, and the router always selects the lowest cost path. If a chain of forward link equipment fails, the forward link assignment manager increases its cost above that of a spare chain, which results in the router selecting the spare chain. Further systems are provided that inform the forward link assignment manager of a failed chain of forward link equipment, in addition to systems that remove a failed chain from the network topology.

Abstract: The invention relates to a device for processing connections which are established by a switching system and associated with a plurality of peripheral devices. Each of the peripheral devices (LTG) is associated with interfaces for devices which communicate with devices both inside and outside the system. The invention is characterized in that each of the peripheral devices has its own logical interface with the message distribution system inside and outside the switching system. The invention is further characterized in that a process control system which is common to the plurality of peripheral devices is also provided. Said process control system processes the tasks assigned to each of the peripheral devices contained in said plurality in exactly the same way as individual process control devices do for each peripheral device.

Abstract: A mechanism for 1:1, 1+1, and UPSR path-switched protection switching, particularly for optical interface units in synchronous optical network (SONET) multiplexer equipment. A working unit and a standby unit pair protect each other in the event of a failure of the working unit or the failure of the span connected to the working unit if both the working and standby units are connected to different spans. Each unit is made responsible for detecting failures of the span that it receives and is primarily responsible for detecting a fault within the unit's own hardware or software. When a unit or span failure is detected, switch control is localized to the two units (i.e. the working and standby unit) which eliminates the need for a third control unit, which reduces processing time and reduces the system hardware.

Abstract: A method of and apparatus incorporating 1+1 protection in a point-to-point radio system includes redundant microwave radio transceiver pairs, each transceiver including identical controls for identifying faults and reconfiguring to accommodate failures. Each transceiver includes receiver and transmitter monitoring circuitry for detecting a loss of received signal or transmitted signal, respectively. Fault signals are generated in response to loss of signal which are then processed by a designated master processor implementing a set of rules for identifying a likely failure corresponding to the faults detected. According to the rule, a partial loss of received signal by one of the receivers indicates a failure of that receiver, while loss of signal by both receivers is interpreted as a failure of the corresponding far-end transmitter. Conversely, receipt of a loss of signal message from a far-end radio station is interpreted as a failure of the active transmitter or the master controller.

Abstract: An active/standby switching system includes two AAL2 (ATM Adaptation Layer Type 2) cell assembling/disassembling processor units (20, 30) as an active system and a standby system so that active/standby switching is carried out between the active system and the standby system. The active/standby switching is carried out by transferring, from one of the AAL2 cell assembling/disassembling processor units (20) which has been the active system to the other AAL2 cell assembling/disassembling processor unit(30) which has been the standby system, handover information to prevent cell loss of AAL2 cells from occurring as a result of the active/standby switching and uncompleted cell data in the course of disassembling, the AAL2 cell assembling/disassembling processor unit (30) to become a new active system receiving the handover information and the uncompleted cell data and carrying out AAL2 cell assembling or disassembling.

Abstract: A protocol is provided for backing up ATM network devices should they fail. The protocol is implemented in a system running ATMARP and supporting IP over ATM. In the protocol, multiple ATM network devices are combined in a “standby group” and share a common IP address. When an active member of the standby group fails, one of the other members of the standby group takes over ATM responsibility for the functions of the failed device. An ATMARP Server determines which member of a standby group should handle IP packets destined for that group.

Abstract: A method and system for providing enhanced peer redundancy in an ATM emulated local area network (ELAN) served by a primary LAN emulation server (LES), a peer LAN emulation server, a broadcast and unknown server (BUS), and a LAN emulation configuration server (LECS). An enhanced peer redundancy virtual channel connection (VCC) is established between the primary LES/BUS and the peer LES/BUS. The primary LES/BUS and the peer LES/BUS exchange status messages every two seconds indicating the number of assigned LECs. If the primary has fewer LECs than the peer, the primary yields to the peer as the active LES/BUS. If an enhanced redundancy VCC was not established, the backup LES/BUS provides ELAN services while waiting for the primary to call to establish an enhanced redundancy VCC. If an enhanced peer redundancy VCC cannot be established, the primary attempts to establish a redundancy VCC with the peer in which the peer LES/BUS is kept in a dormant mode as long as the redundancy VCC is present.

Abstract: The specification discloses methods and apparatus for selecting the better of two or more copies of a cell in a cell-oriented redundant switching system connected to an external communications network. In the preferred embodiment, the best cell copy selection aligns redundantly transmitted cell streams before selecting cells for insertion in the data stream. Because the streams are aligned before the selection is made, the best cell copy selector compares each cell at the same instant in time, rather than basing its selection on past events.

Abstract: The present invention provides a VP protection system and a VP protection method which forward messages quickly to nodes on an ATM network when an error occurs on the ATM network and reduce an error recovery time. The VP protection system, for use on an ATM network that includes a plurality of ATM nodes performing protection, a plurality of working VPs, and a plurality of standby VPs, exchanges messages among ATM nodes when an error occurs, one group of VPs at a time. An intermediate ATM node in a standby path at least comprises a VPG resource information management table, a VP resource information management table, a VPG configuration information management table, a VPG switching message receiving circuit, a VPG switching message sending circuit, node resource management circuits, a VPG resource allocation circuit, a VP expansion circuit, and a VP resource distribution circuit.

Abstract: A service message system for a switching architecture including at least one Switch Fabric (10, 20) comprising a switch core (15, 25) located in a centralized building and a set of Switch Core Access Layer (SCAL) elements distributed in different physical areas for the attachment to the different Port adapters (30, 31). Each SCAL elements particularly includes a SCAL receive element (11-i) and a SCAL Xmit element (12-i) for the respective access to one input port and one output port via serial links. The service message is based on the use of a Cell qualifier field at the beginning of each cell, which comprises a first and a second field. The first field is the Filtering Control field which permits an easy decoding of a service message cell, when applicable. The second field is used for determining which particular type of service message is conveyed via the cell.

Abstract: A system is provided for asymmetrically maintaining system operability that includes a first processing element and a second processing element coupled to the first processing element by a communication link. The first processing element is operable to perform at least one function. The second processing element is operable to perform at least one function of the first processing element in the event the first processing element fails, and further operable to expect and receive keepalive inquiries at an expected rate from the first processing element and to send responses in response to the inquiries to the first processing element. The second processing element is further operable to take remedial action after not receiving any inquiries within a first predetermined time period.

Abstract: A fault tolerant network switch includes two or more switches units and a highly reliable (i.e., one with no single point of failure) interconnect unit so that during normal operation both switches are actively handling network packets and upon the failure of one of the switch units, another switch unit takes over, ensuring continued normal network operation, with somewhat reduced performance. The failed switch unit can then be replaced and the network returned to its original performance without disturbance to the other switch or the network cable connections.

Abstract: An information processing system and an information terminal thereof and, in particular, an information processing system and an information terminal thereof are provided in which business work can be continuously performed via an external network, such as the Internet, by co-operating with a high-ranking host computer even during a failure. In an information processing system in which the information terminal communicates with the information processor in an external IP network via a main circuit for normal use or a secondary circuit for use when a failure occurs, provided with the router, the information terminal has a communication failure detecting means to detect a communication failure at an application level during communication with the information processor, and route switching instruction means to instruct to the router to switch from a main circuit to a secondary circuit by detecting the communication failure.

Abstract: A method and system for routing video calls includes one or more video endpoints. An array of infrastructure routing elements transmits the video calls between the video endpoints along one or more principle routes and one or more back-up routes. The system and method further includes a video network platform in communication with the video endpoints and the infrastructure routing elements, and the video network platform prioritizing the principle routes and the back-up routes. A scheduling engine associated with the infrastructure routing elements is operable to monitor the performance of the infrastructure routing elements, determine a reliability model for each infrastructure routing element, and intelligently route the video calls based on the reliability models without losing communication between the video endpoints.

Abstract: A switching system having at least two switch fabrics. Each fabric has a switch core and a set of SCAL (Switch Core Access Layer) receive and transmit elements. The switch cores are preferably located in the same physical area but the SCALs may be distributed in different physical areas. Port Adapters distributed at different physical areas are connected to the switch fabrics via a particular SCAL element so that each switch core can receive cells from any port adapter and conversely any port adapter may receive data from either switch core. Control logic assigns a particular switch core to one port adapter for normal operations while reserving the other switch core for use when the first core is out of service. Each switch core has a mask mechanism which uses the value in a mask register to alter a bitmap value which controls the routing process. The mask registers in the two switch cores are loaded with complementary values.

Abstract: In a duplex call control unit for SVC connection, call control parameters with respect to SVC connection information with regard to SVC connection which has already been established and call control parameters with respect to the statuses of call control protocols for SVC connection which is being established or being released are stored in a call control parameter database section. The parameters are referred to by a first call control section or a second call control section that is operating as a standby system call control section or that is restarting working, and thereby call control parameters of the call control section is adjusted.

Abstract: There is disclosed, for use in a packet switched network, a redundant switch comprising 1) a primary packet router for routing a first stream of data packets from an input interface to an output interface of the redundant switch; 2) a secondary packet router for routing a second stream of data packets corresponding to the first stream of data packets from the input interface to the output interface; 3) a packet ID generator for attaching a unique identifier to each data packet in the first stream of data packets and attaching the same unique identifier to each corresponding data packet in the second stream of data packets; and 4) a comparator for comparing a first unique identifier associated with a first data packet processed by the primary packet router with a second unique identifier associated with a second data packet associated with the secondary packet router.

Abstract: A stackable network unit comprises a ‘down’ port and an ‘up’ port, an arbitration path for data packets from the down port to the up port, a repeat path for data packets from the up port to the down port, a link detector for detecting tile absence of another operative unit connected to the down port to cause data packets on the return pat to bypass the down port and proceed on the arbitration path and for detecting the absence of another operative unit connected to the up port to cause data packets on the arbitration path to bypass the up port and proceed on the repeat path.

Abstract: A switching system for a data traffic network. A plurality of line cards provide input and output connections to a plurality of data lines and further are connected to at least two switch fabrics, one of which is designated the active switch fabric and the other designated the standby switch fabric. Data traffic is switched between the plurality of input and output line cards by the active switch fabric. When it is desired to change the active switch fabric assignment, for example due to a fault in the switch fabric, data transmissions into the active switch fabric are terminated and a drain timer is started. When the drain timer times out or the active switch provides an indication that it is empty, the active switch fabric assignment is swapped to the standby switch fabric and data is then switched through the newly assigned active switch fabric.

Abstract: A redundancy system for a telecommunications system is provided. The redundancy system includes one or more resources, such as circuit cards containing circuits that process data for telecommunications channels. A controller bus is used to connect a controller to the resources. Another controller bus is also used to connect another controller to the resources. The resources are each coupled to the controller bus and the other controller bus, such that a change in control between the controller and the other controller may be accomplished by transferring data for the resources from the controller bus to the other controller bus.

Abstract: A hitless switching system in an asynchronous transfer mode (ATM) apparatus, includes a first system switch section and a second system switch section. The first system switch section has a first cell buffer, and sequentially stores a sequence of cells in the first cell buffer to sequentially output the stored cells from the first cell buffer while performing a discard priority control to the sequence of cells. Also, the first system switch section stops the discard priority control when a switching control cell is detected in the sequence of cells. The second system switch section has a second cell buffer, and sequentially stores the input cells in the second cell buffer to sequentially output the stored cells from the second cell buffer while performing the discard priority control to the sequence of cells.

Abstract: A failover transition system for a VLAN is disclosed in which a master switch and a standby switch are designated, as in the case of ESRP. When a network failure is detected, the master switch “bounces” or restarts auto-negotiation of a set of physical ports on the VLAN. In this way, ports are forced to re-ARP to update their forwarding database information immediately rather than wait until expiration of an ARP max age timer, resulting in a decreased failover transition time.

Abstract: A method and apparatus to provide redundancy in a network is described.

Abstract: A data communications network having a primary router, a secondary router and a peer router is disclosed. In operation the primary and peer router conduct a peer session to exchange information regarding the current state of the network topology. In addition, the secondary router monitors the peer session to maintain awareness of the current state of the network topology and replaces the primary router upon detecting a failure of the primary router.