Abstract: A second link in a network is reconfigured after failure of a first link, so that multiple-link failures may be survived. After receipt of an OSPF link state advertisement (LSA) indicating use of a backup path bl after the failure of link l, new backup paths are determined for each impacted link (x,y) that has a backup path sharing one or more links with the backup path bl. The new backup paths are computed while ignoring the failed link l, the impacted link (x,y), and links common to the backup paths b(x,y) and bl. The LSA protocol is modified to accommodate information used in determining whether a link is an impacted link.

Abstract: Systems, methods and computer-readable media for utilizing spare link capacities of links within a communications network are described. According to one aspect, a method for utilizing spare network capacity on a communications network includes determining a spare capacity of a plurality of links within the communications network. Upon determining the spare capacity of the plurality of links, a portion of the plurality of links according to the spare capacity of the plurality of links is selected. A standby network including the selected portion of the plurality of links is established, and traffic is routed through the standby network.

Abstract: A system includes a network element communicatively coupled to another network element through an intraportal link forming a node portal. The network element is communicatively coupled to a source network element within a network attached to the node portal. The network element is configured to monitor a protect path for an automatic protection switching (“APS”) message from the source network element, determine that the APS message has been received, monitor an intraportal link for an expected message from the other network element, determine that the expected message has not been received, monitor integrity of the intraportal link, determine that the intraportal link has failed and determine that the other network element has failed based upon determining that that the APS message has been received, that the expected message has not been received, and that the intraportal link has failed.

Abstract: Methods, systems, apparatuses, and computer-readable media are provided for scanning a primary repository for one or more matching primary wireless profiles corresponding to one or more wireless networks, executing a primary connection cycle responsive to a determination that the primary repository stores the one or more matching primary wireless profiles, scanning one or more secondary repositories for one or more matching secondary wireless profiles corresponding to the one or more wireless networks if no matching primary wireless profile is discovered or the primary connection cycle fails, and executing a secondary connection cycle responsive to a determination that the one or more secondary repositories store the one or more matching secondary wireless profiles.

Abstract: Provided is an electric product. The electric product includes: a communication modem including a printed circuit board; a first communication unit installed at the printed circuit board and performing communication by using a first communication type; and a second communication unit installed at the printed circuit board and performing communication by using a second communication type different from the first communication type; a control unit transmitting/receiving a signal to/from the communication modem; and a load receiving power and controlled by the control unit; wherein the first communication unit and the second communication unit are installed at different corners of the printed circuit board.

Abstract: The protection of multi-segment pseudowires by utilizing backup paths is disclosed herein. Disclosed embodiments include methods that establish at least one backup path for multi-segment pseudowires, the establishing being performed prior to detection of failure in the primary path. Upon detecting a path failure, the detected failure is signaled to the head-end, a backup path is chosen, and reachability information associated with the chosen backup path is signaled across the backup path before reverse traffic is switched to the backup path. In other disclosed embodiments, apparatus are configured to establish, prior to detection of failure in the primary path, at least one backup path for the multi-segment pseudowire.

Abstract: A method of routing packets across a packet switched network domain, comprising a multiplicity of nodes. Each node comprises an ingress interface and an egress interface. For each destination node a default and a detour branching are defined, each specifying a route to the destination node. For each two-edge connected node the default and detour branchings do not share a common ingress interface.

Abstract: An emergency backhaul link is created between a first radio base station and a second radio base station over an air interface in response to an interruption or failure of a primary backhaul link of the first radio base station. In some embodiments, the first radio base station and the second radio base station are provided with no additional equipment to support the emergency backhaul link. In other embodiments, the second radio base station includes a tunable receiver configured to switch between receiving mobile device traffic on an uplink frequency and receiving backhaul traffic on a downlink frequency. In other embodiments, the second radio base station includes a receiver configured to receive backhaul traffic from the first radio base station over a downlink frequency. After the primary backhaul link is restored, the emergency backhaul link is torn down and backhaul traffic resumes on the primary backhaul link.

Abstract: An information handling system is provided. The information handling system includes a first network switch configurable, the first network switch having a computer processor in communication with a plurality of ports for receiving and sending frames and a memory coupled to the computer processor and including a media access control (MAC) address table. The computer processor is configured to read frames, each frame having a header, and is also configured to associate a MAC address with a parent link aggregation group (LAG) except while a downstream link failure is detected. The computer processor is configured to associate the MAC address with a sub-LAG while a downstream link failure is detected. Methods for directing traffic through a virtual link trunking (VLT) domain during failure of a downstream link are also provided.

Abstract: Embodiments disclosed herein provide redundant connectivity between an Ethernet Automatic Protection Switching (EAPS) access network and a Virtual Private LAN Service (VPLS) network. A first VPLS node is provided to function as an EAPS controller node. A second VPLS node is provided to function as an EAPS partner node. The first and second VPLS nodes are linked by a pseudowire and an EAPS shared-link. Additional EAPS nodes are also provided. The additional EAPS nodes are linked to each other and one of the additional EAPS nodes is designated as a master node. Links are also established between the VPLS nodes and the EAPS nodes such that one or more EAPS rings are formed. Each EAPS ring includes the shared-link between the first and second VPLS nodes. The EAPS rings are monitored to detect link failures.

Abstract: An access network is described in which a centralized controller provides seamless end-to-end service from a core-facing edge of a service provider network through aggregation and access infrastructure out to access nodes located proximate the subscriber devices. The controller operates to provide a central configuration point for configuring aggregation nodes (AGs) of a network of the service provider so as to provide transport services to transport traffic between access nodes (AXs) and edge routers on opposite borders of the network.

Abstract: A method for providing an uplink over an access ring comprising access devices and at least one aggregation device, wherein each device of said access ring has ring interfaces connecting said device to neighboring devices in said access ring, wherein one access device of said access ring is configured as a ring master device which sends connectivity check messages on both its ring interfaces around said access ring to itself to detect a connectivity failure in said access ring, and wherein said ring master device changes a state of one of its ring interfaces depending on the detection result.

Abstract: Methods and systems for locating Mobile Stations (MSs) that are served by a Wireless communication Network (WLN) in a given geographical area. The MSs typically communicate with other parties, or connect to the Internet, through the WLN, wherein Base Transceiver Stations (BTSs) serve as the WLN front ends from the MSs perspective. A Stimulating Apparatus (SA) monitors control messages that the BTSs in the area of the SA broadcast to MSs. The SA analyzes the control messages that it receives, selects one transmitting BTS and creates a modified version of the control messages that it has received from the selected BTS. The SA then broadcasts the modified messages on behalf of the selected BTS by using its frequency channel. The discrepant transmission parameters are designed to stimulate any MS that receives them to induce a network event from which the MS location may be estimated.

Abstract: A method and apparatus for reporting events in a machine-to-machine environment are provided. Upon detection of an event, a determination is made whether to report the event with or without a delay. If the event is to be reported with a delay, then reporting is delayed for a period of time. If an event notification is received prior to the expiration of the delay period, then the reporting of the event may be canceled as event has already been reported by another element. If not, then another determination is made whether to report the event with or without another delay. This process continues until either the event has been reported or an event notification corresponding to the event has been received from another element.

Abstract: A connection oriented communications network has a plurality of nodes including a plurality of edge nodes. The network is arranged to define a primary tunnel connecting a primary one of the edge nodes to another edge node and a secondary tunnel connecting a secondary one of the edge nodes to another edge node. The network is arranged to enable switching of traffic from the primary tunnel to the secondary tunnel in the event of detection of a failure in the primary tunnel.

Abstract: A media source sends media packets over a first media path. Repair packets are encoded from the media source packets and sent over a second different media path. Sending the source packets and repair packet over different media paths is referred to as Forward Error Correction (FEC) spatial diversity and reduces the amount of repair packet overhead required for repairing the media source packets in case of a network outage or packet loss. To provide load balancing, a first set of media streams may be sent over the first media path and a second set of media streams may be sent over the second media path. If a fault is detected on one of the media paths, then the repair packets may no longer be transmitted and the one or more media streams from the disabled media path are transmitted over the working media path.

Abstract: An apparatus for implementing policy control for home gateway comprises a Co-located Policy Decision Function Entity (PD-FE) for receiving the QoS policy issued by the PD-FE at network side and sending the QoS policy to the home gateway or issuing the QoS policy configured thereon to the home gateway. A method for implementing the policy control for home gateway, the method comprises: the Co-located PD-FE receiving the QoS policy issued by the PD-FE at network side or being configured with the QoS policy; and the Co-located PD-FE issuing the QoS policy to home gateways. With the present invention, the Resource and Admission Control Function (RACF) avoids controlling the home gateway directly or sending the policy to the home gateways in the case that there are a lot of home gateways and all the home gateways are scattered at the edge of the network.

Abstract: A method of recovering a fault in a multilayer network and an apparatus thereof are provided, the method including obtaining lower layer backup path setting information through a signaling message that is used for a label based path setting, setting a backup path at a lower layer based on the obtained lower layer backup path setting information, and upon detecting a fault at the lower layer, performing a protection switching through the set backup path at the lower layer.

Abstract: A method is provided in one example and includes communicating a first request message to a first network element functioning as a point of local repair for a backup label switched path. The first request message includes a first network address having a predetermined value and an indication of a forwarding equivalence class associated with the backup label switched path. The method further includes receiving a first reply message from the first network element. The first reply message includes at least one backup path parameter associated with the backup label switched path.

Abstract: One embodiment of the present invention provides a switch. The switch comprises one or more ports and a link management module. The link management module operates a first aggregate link group as an active aggregate link group of a protected virtual link aggregation. This protected virtual link aggregation operates as a single logical channel. An aggregate link group comprises a plurality of logically aggregated links. The first aggregate link group, which represents the logical channel, comprises at least a first port of the one or more ports of the switch. The link management module also operates a second aggregate link group of the protected virtual link aggregation as a standby for the first aggregate link group. The second aggregate link group comprises at least a second port of the one or more ports of the switch. Forwarding is enabled via the first port and disabled via the second port.

Abstract: A computing device may receive first message data associated with a messaging group. The computing device may associate the first message data with a messaging thread. The computing device may associate a unique session identifier with one or both of the messaging thread and the messaging group. For a first one or more user devices of the messaging group, the computing device may send the message data along with the unique identifier via a native messaging protocol. For a second one or more of the user devices of the messaging group, the computing device may associate a fallback identifier of each of the one or more second user devices with one or both of the messaging thread and the messaging group, and send the first message data and unique identifier via a fallback messaging protocol.

Abstract: Disclosed is an adaptive multi-redundant ring network system using a 2 port Ethernet communication module capable of selecting a path, the network system including a main network system including a first main control unit and a plurality of first slaves; and a sub-network system including a second main control unit and a plurality of second slaves, wherein each of the plurality of first slaves and each of the plurality of second slaves include 2-port Ethernet communication modules, and each of the plurality of first slaves, each of the plurality of second slaves, the first slave and the second slave are selectively connected via the 2-port Ethernet communication modules.

Abstract: A method includes establishing a bi-directional pseudowire (BPW) between a first provider edge (PE) router and a second PE router that are forwarders for a multi-homed VPLS customer site associated with a VPLS domain. The first PE router has a designated forwarder status and the second PE router has a backup forwarder status relative to the VPLS customer site. The BPW is established as an auxiliary standby BPW external to the VPLS domain. The method also includes detecting a change in topology of the network with the first PE router, wherein the change in topology affects connectivity by the first PE router to the VPLS customer site associated with the VPLS domain, and, upon detecting the change in topology, utilizing the BPW as an active interface within the VPLS domain for forwarding network traffic to the VPLS customer site.

Abstract: A method and apparatus for implementing ProSe (Proximity Services) are disclosed. The method includes using ProSe communication with direct mode data path. The method also includes sending a request to an eNB (evolved Node B) to establish ProSe communication with locally-routed data path.

Abstract: A wireless transmit/receive unit (WTRU), supporting Long Term Evolution (LTE), to perform circuit switched (CS) fallback is provided. The WTRU may receive via a packet switched (PS) radio access technology (RAT) a paging message including an International Mobile Subscriber Identity (IMSI). The paging message may have a domain indicator indicating that the paging message is from a CS network. The WTRU may fallback to CS and subsequently use the IMSI.

Abstract: Embodiments of the present invention are directed to implementing high-radix switch topologies on relatively lower-radix physical networks. In one embodiment, the method comprises constructing the physical network (702) composed of one or more optical switches connected via one or more waveguides. A desired switch topology (704) is then designed for implementation on the physical network. The switch topology is then overlain on the switch network by configuring the optical switches and waveguides (706) to implement the switch topology on the physical network. The optical switches can be reconfigured following a transmission over the physical network and can be configured to implement circuit switching or packet switch.

Abstract: A set of virtual local area networks (VLANs) are defined from a set of nodes that comprise a data center network. A set of possible paths are determined for routing data packets from a root node to one or more other nodes of the set of nodes. A set of probabilistic values are identified for determining a path in the set of possible paths that individual data packets are to take as between the root node and a destination node specified by the individual data packet. The data packets are routed to the destination node specified by that data packet, along a path that is determined by use of the set of probabilistic values. The path may be provided by one or more VLANs.

Abstract: In the embodiments of the present invention, proposed is a method in which a CoMP enabled UE chooses the BSs to be in its cooperating set and a BS partitions its bandwidth to serve its own UEs and UEs from other cells that have requested it to be in its cooperating set.

Abstract: In subscriber units 0 to (N?1), a subscriber unit to be allocated to a bandwidth is defined as a subscriber unit K, where K is an integer from 0 to (N?1) inclusive. In a bandwidth allocating method, a free bandwidth in a communication channel ch(K?1) not used by the subscriber unit (K?1) is found, and a bandwidth requested by the subscriber unit K is allocated to the free bandwidth in the communication channel ch(K?1). A free bandwidth in the communication channel chK is found on the basis of a residual bandwidth requested by the subscriber unit K not allocated to the bandwidth in the communication channel ch(K?1), and the residual bandwidth requested by the subscriber unit K is allocated to the found free bandwidth in the communication channel chK. The operation is repeated for the subscriber units 0 to (K?1) and (K+1) to (N?1).

Abstract: Device coexistence within single user, multiple user, multiple access, and/or MIMO wireless communications. Different respective communication devices operating using different respective communication channels having different respective channel bandwidths may be implemented within a given communication system. For example, different respective communication devices may belong to different basic services sets (BSSs) (e.g., a 1 MHz BSS operating using channel bandwidths of 1 MHz, and a 2 MHz BSS operating using channel bandwidths of 2 MHz). To effectuate coexistence among different respective devices operating using different respective channel bandwidths, devices but longing to the 1 MHz BSS monitor for and listen for 2 MHz wide communication activity, and those 1 MHz BSS communication devices defer to any detected communication activity on any portion of the 2 MHz channel.

Abstract: A method and apparatus are provided for enabling spare capacity allocation (SCA) in a network for protecting against dual link failures using a successive survivable routing (SSR) algorithm that has better scalability and shorter computation time than other techniques. An embodiment method implemented by an apparatus includes computing the SCA for a plurality of flows in the network for a plurality of primary backup paths and a plurality of secondary backup paths corresponding to a plurality of working paths for the flows using a SSR algorithm. Another embodiment method includes computing the SCA for each of a plurality of flows in the network for a plurality of primary backup paths and a plurality of secondary backup paths corresponding to a plurality of working paths for the flows using a SSR algorithm, and aggregating the computed SCA for the primary backup paths and the secondary backup paths for all the flows.

Abstract: “A home system for managing an internet network (9) access connection in which at least one computer (80) can access the internet by way of a main home connection (8). The system contains means (83) capable of detecting a failure to connect to the internet network (9) on the main home connection (8) and of controlling an automatic failover to a back-up connection comprising a control box (5) of a system for the real-time measurement and modulation of the power consumption of a plurality of electrical appliances (2). The control box (5) is capable of accessing the internet network (9) by way of a wireless connection (6) of packet telephony type.

Abstract: An operating method of a Base Station (BS) in a wireless communication system supporting a wireless link based communication between BSs is provided. The method includes, if a wireless link with a counterpart BS is interrupted, transmitting a report on the wireless link interruption to a management server, receiving information about at least one candidate BS for a detour path from the management server, determining a detour path with the counterpart BS on the basis of the information about the at least one candidate BS, and performing communication with the counterpart BS through the detour path.

Abstract: In one embodiment, a set of tunnels is determined that traverse a particular link connected to an intermediate node in a network. The intermediate node computes, in a coordinated path computation, paths for tunnels of the set of tunnels that do not include the particular link. The coordinated path computation considers each of the tunnels of the set of tunnels. The intermediate node selects one or more tunnels of the set of tunnels for preemption. The one or more tunnels are selected as tunnels that are reroutable by respective head-end nodes of the one or more other tunnels. Notifications are sent to one or more other intermediate nodes that inform the one or more other intermediate nodes of the one or more tunnels selected for preemption.

Abstract: A communications link of multiple parallel communications lines includes at least one redundant line. In a first aspect, the lines are periodically recalibrated one at a time while the others carry functional data. If a fault is detected, the faulty line is disabled and the remaining previously calibrated lines transmit functional data. In a second aspect, impending line malfunction is detected from anomalies during calibration. In a third aspect, line malfunction is detected from receiver circuit output by determining a logical lane upon which each detected error occurs, and by mapping the logical lane to a physical line currently carrying the logical lane data.

Abstract: A method including providing pseudo-streaming media data to a terminal; receiving a transport control protocol (TCP) acknowledgement from the terminal; estimating one or more network conditions of a network based at least in part on the TCP acknowledgement; determining an optimal session bitrate based on the estimated one or more network conditions; and providing pseudo-streaming media data to the terminal based on the optimal session bitrate.

Abstract: In one embodiment, the present disclosure is a method and apparatus for provisioning a backup signaling channel. In one embodiment, a method for provisioning a backup D channel in a media gateway includes provisioning a primary D channel on a first media gateway card in the media gateway and provisioning the backup D channel on a second media gateway card in the media gateway that is different from the first media gateway card, wherein the backup D channel backs up the primary D channel.

Abstract: A differential protection system is provided. The differential protection system includes a local terminal configured to be communicatively coupled directly or indirectly with at least two remote terminals via at least three communication links to form a ring topology or a mesh topology. The differential protection system further includes a controller comprising a communication link decision unit and a clock unit associated with the local terminal. The communication link decision unit is configured to determine some of the at least three communication links as virtually disconnected such that the ring topology or the mesh topology is configured to be converted to a daisy chain topology. The clock unit is configured to time synchronize the local terminal with at least one of the at least two remote terminals when the local terminal and the at least two remote terminals are configured in the daisy chain topology.

Abstract: A method is executed by a controller in a software defined network to conserve bandwidth over the software defined networking (SDN) network by compressing Internet protocol (IP) headers of data packets traversing the SDN network. The IP headers of the data packets remain compressed as the data packets traverse the SDN network. The ingress switch is an entry point for the data packets as the data packets traverse the SDN network. The egress switch is an exit point for the data packets as the data packets traverse the SDN network. The method includes configuring a flow table of the ingress switch to forward the data packets to a header compressor module in the ingress switch, configuring the ingress switch to instantiate the header compressor module, and configuring a group table of the ingress switch to manage forwarding of the data packets toward the egress switch.

Abstract: System and method embodiments are provided herein to obtain minimum or optimal spare capacity allocation (SCA) using partial disjoint paths (PDP) for bi-connected network topology. Both an integer linear programming (ILP) optimization model and an approximation algorithm, referred to herein as Successive Survivable Routing (SSR), are formulated for resolving the SCA with PDP. The embodiments include assigning a working path and a primary backup path on two disjoint routes between two end nodes, and assigning a plurality of secondary backup paths that are partially disjoint and that each pass through one fiber cut group on one of the two disjoint routes and all remaining fiber cut groups on the other one of the two disjoint routes. Each of the fiber cut groups includes all fiber cut pairs on both disjoint routes that have the same effect of interrupting a flow on both disjoint routes.

Abstract: Wireless line termination units 21 and 22 respectively transmit and receive frames via wireless lines 51 and 52. Line termination units 25 and 26 respectively exchange frames with the wireless line termination units 21 and 22. The wireless lines 51 and 52 are treated as one virtual line. A radio monitoring unit 272 monitors the state of the wireless lines 51 and 52, and in accordance with the redundancy mode, instructs the wireless line termination units 21 and 22 to exchange copy frames with other wireless line termination unit and to abandon received frames. A communication path control unit 273 sets, in accordance with the monitoring result as to the state of the wireless lines by the radio monitoring unit 272, the line termination units 25 and 26 to each be an active system or a standby system. A switch core 271 passes frames to be transmitted to the line termination unit that operates as the active system.

Abstract: An apparatus and method for operating a base station and a mobile station in a communication system are provided. The operation of the base station includes persistently allocating resources to at least one mobile station and transmitting, in a current frame, a control information message including a change counter flag indicating whether persistent resource allocation information, transmitted in a previous frame, is changed. An operation of the mobile station includes receiving a control information message, including a change counter flag indicating whether persistent resource allocation information included in a control information message transmitted in a previous frame is changed, from a base station in a current frame and checking a value of the change counter flag.

Abstract: Determining a failure of a logical connection in a logical circuit identified by a logical circuit identifier, the logical circuit comprising variable communication paths in at least one of a first or a second logical telecommunications network and a fixed communication path between the first and second logical telecommunications networks, and the failed logical connection being between the first and second logical telecommunications networks; identifying a logical failover circuit comprising an alternate communication path in a failover network that is separate from the logical circuit, the failover network reserved to provide failover circuits to communicate data rerouted from failed logical circuits, and the logical failover circuit identified by a second logical circuit identifier; renaming the logical circuit identifier of the logical circuit to the second logical circuit identifier of the logical failover circuit; and rerouting the data from the logical circuit to the logical failover circuit without ma

Abstract: Disclosed are a node and a method of transmitting packets from the node. The disclosed node may use a directional antenna for transmitting a packet. The node includes a determining unit and a forwarding unit. The determining unit may determine whether or not there is an actor node present in a region traversed by a packet forwarding direction, where the packet forwarding direction is determined from relative-location information of a destination node with respect to a source node, the region is one of a plurality of regions divided by particular angles, and the plurality of regions have multiple beam patterns of the node formed therein. The forwarding unit may transmit the packet to an actor node present in the region traversed by the packet forwarding direction or transmit the packet to a neighbor node present in the region traversed by the packet forwarding direction.

Abstract: The invention relates to a monitoring system, having an output module for generating a control signal in response to an input signal, a monitoring module for generating the input signal for the output module, an output device for outputting an output signal in response to the control signal, and a feedthrough device for preventing outputting of the output signal. According to the invention, the monitoring module is designed to instruct the feedthrough device to prevent outputting of the output signal when there is a deviation between the control signal and a control signal which is expected on the basis of the input signal.

Abstract: A method including receiving network topology and resource management information; generating a mapping between the network topology of a network and resource reservation paths associated with flows using the network based on the network topology and resource management information; generating a failure recovery plan (FRP) based on the mapping, wherein the FRP instructs one or more other network devices on how to manage a failure such that one or more resource reservation paths associated with flows impacted by the failure are not deleted; and loading the FRP on the one or more other network devices.

Abstract: A method and apparatus for status transition are provided in the disclosure, which enable a wireless side network element to judge that a service request message is a paging response message after receiving the service request message, transmit an initial user equipment message to a mobility management entity, and indicate that the service request message is valid in the initial user equipment message. The method and apparatus of the disclosure solve the problem that the mobility management entity is unable to make a correct judgment and corresponding logical processing, and improve processing efficiency of the mobile communication system effectively.

Abstract: An apparatus is provided for control of a plurality of forwarding switches using a network controller. The network controller executes a routing configuration application that analyzes interconnections between the forwarding switches to identify a topology of the network, determine label switched paths (LSPs) between the forwarding switches, and transmits the next hop routes to the forwarding switches. The forwarding switches use the next hop routes to route packets through the network according to a multiprotocol label switching (MPLS) protocol. Each LSP includes one or more next hop routes defining a forwarding address associated with one forwarding switch to an adjacent forwarding switch.

Abstract: Nodes and methods are disclosed for protection and restoration to protect against multiple failures for multiple paths involved for the same service in mesh networks, including, determining, by circuitry of a first node in a mesh network, a failure of a working path between the first node and a second node, wherein the second node, when triggered by the failure of the working path, switches to a protection path. Methods further include establishing through transmission of at least one signal by circuitry of the first node at least one recovery path, for example, a restored-working path, after determining the failure of the at least one working path, wherein the at least one restored-working path carries a duplicate of the data traffic transmitted on the protection path in case of failure of the protection path.

Abstract: A method and apparatus for post-silicon repair of on-die networks is disclosed. In one embodiment, an integrated circuit includes a first network node of an on-chip network configured to couple each of a plurality of functional units to at least one other one of the plurality of functional units. The first network node includes a plurality of ports. Each of the plurality of ports includes a plurality of multiplexers configured to substitute a spare channel of the network node into the network responsive to a test determining that another one of a plurality of channels is defective.