Abstract: A communication control apparatus includes a storage unit and a processor. The storage unit stores, in association with a port number, first address information regarding apparatuses connected to a port identified by the port number. The processor receives a first affected address list containing second address information regarding apparatuses which may be affected by a trouble, extracts the first address information stored in the storage unit in association with a port number of a port via which the first affected address list has been received, selects third address information which is included in both the first and second address information, updates the first affected address list by replacing the second address information with the third address information to acquire a second affected address list, and transmits the second affected address list via each port other than the port via which the first affected address list has been received.

Abstract: A protocol circuit layer is described. The protocol circuit layer may employ a routing layer to determine optimal routes when establishing a circuit. The circuit layer may employ a link layer to send data packets over links to other network nodes. A naming layer may employ circuits to establish a distributed database of associations between network node addresses and their network locations.

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: Novel tools and techniques are described for mitigating data loss during failover in a VPLS multi-homed network. In one aspect, a primary link might be established between a lowest numbered provider edge (“PE”) router in the service provider network and a lowest numbered physical site at customer premises outside the service provider network. A stability site might be established within the service provider network, communicatively coupled to at least the lowest numbered PE router via a primary virtual circuit. The stability site might be designated as the lowest numbered virtual site, which might have a site ID number lower than the lowest numbered physical site. In response to the primary link failing or becoming broken, one or more backup virtual circuits might be established between a plurality of ingress PE routers and a plurality of egress PE routers in the service provider network, without destroying the primary virtual circuit.

Abstract: A method for convergence of multicast traffic in response to a topology change. The method includes, in response to a change in a multicast topology, redirecting multicast traffic through a network device of a plurality of network devices in the multicast topology and determining a querier status of the network device. The method also includes flooding the multicast traffic through an interface to the network device to facilitate convergence of the multicast traffic. The interface is a connecting point between the network device and another network device of the plurality of network devices.

Abstract: Techniques for facilitating link redundancy using an enhanced version of Virtual Switch Redundancy Protocol (VSRP), referred to herein as VSRP2. In one set of embodiments, a group of Layer 2 and/or Layer 2/3 devices (switches) can act in concert as a VSRP2 virtual switch. A first switch in the group (a VSRP2 master switch) can forward, via a first link, data traffic to/from a network device in a connected Layer 2 network. A second switch in the group (a VSRP2 backup switch) can block, at a second link, data traffic to/from the same network device. If the first link fails or otherwise becomes unavailable, the VSRP2 backup switch can detect the link failure and begin forwarding, via the second link, data traffic to/from the network device. In this manner, redundancy can be provided at the link level between the VSRP2 virtual switch and the Layer 2 network.

Abstract: A method, computer readable medium and apparatus for providing a back-up internet protocol (IP) connection are disclosed. For example, the method monitors a primary IP connection to a subscriber premises, detects a failure or a degradation of the primary IP connection to the subscriber premises and activates a back-up IP connection to the subscriber premises.

Abstract: A network system has a computer device, and a plurality of node devices communicatively connected to the computer device via network with one or more sensor devices allowed to be connected to each of the plurality of node devices via wireless communication. Each of the node devices obtains sensor data from the sensor device which is connected to the node device itself via the wireless communication and saves the sensor data in a sensor data storage section incorporated in the node device itself. The computer device specifies and requests via the network sensor data that any one or more of the one or more sensor devices obtained, and obtains via the network the specified sensor data from the node device which has saved the specified sensor data in the sensor data storage section among the plurality of node devices.

Abstract: Systems and methods for providing a stable communication between a vehicle's on-board connectivity layer include at least one vehicle located communication node and at least one vehicle associatable communication node, and an off-board connectivity layer including at least one remote system located communication node, wherein each communication node communicates with at least one other communication node over a communication connection, and in case the communication connection to the at least one communication node is disturbed or interrupted, a communication connection to another communication node is established.

Abstract: A method for routing communications on a network node in a communications network includes: updating a central domain master regarding changes detected in topology, receiving a routing plan from the central domain master, where the routing plan is calculated at least in accordance with the changes, and transmitting data as necessary in accordance with the routing plan. A method implementable on a central domain master for routing communications between network nodes in a communications network includes receiving transmissions regarding changes detected in topology from the network nodes, calculating a routing plan based on at least the transmissions, and distributing the routing plan to the network nodes, where the central domain server is one of the network nodes.

Abstract: An example method involves, when a first quality of service parameter for a failed logical circuit is equal to or less than a second quality of service parameter for a logical failover circuit, rerouting data from the failed logical circuit to the logical failover circuit without requiring authorization from a customer to communicate the data at the second quality of service parameter. When the second quality of service parameter for the logical failover circuit is a lower level of quality than the first quality of service parameter for the failed logical circuit: a customer is prompted for an authorization to communicate the data via the logical failover circuit at the second quality of service parameter; when the authorization is received, the data is rerouted from the failed logical circuit to the logical failover circuit; and when the authorization is denied, the data is not rerouted to the logical failover circuit.

Abstract: A connection-oriented network has a working path and a segment recovery path for a segment of the working path. The working path has a branch node at an end of the segment where the segment recovery path connects to the working path. The branch node is not located at an end node of the working path. Control plane signalling is received at an end node of the working path from a node along the working path, indicating that a failure has occurred along the working path. The end node determines, from the received control plane signalling, if the failure has occurred outside the segment of the working path. When it is determined that the failure has occurred outside the segment of the working path, a notification is sent to the branch node. The notification is an instruction not to reroute to the segment recovery path.

Abstract: Methods and arrangements are provided for minimizing delay in a high-speed tap arrangement are disclosed and include hardware and software arrangements and methods for quickly switching the transmission path for data between a primary data path and a bypass data path. The switching is accomplished rapidly using set of powered analog switches and a relay to minimize packets loss in the event of power loss. Further, when power is restored, software and hardware methods and arrangements disclosed herein permit the data path to be promptly restored resulting in the restoration of tapping ability quickly after power is restored.

Abstract: A method, apparatus and computer program product are presented. In a system having at least one Multi Link Trunk/Link Aggregation Group (MLT/LAG), a table is provided for each MLT/LAG, each table having at least one entry, each entry including at least two fields, a first field comprising a port member identification (ID) field and a second field comprising a port member status field. A port member status is checked for a port when a packet flow hashes into the table, and the status for the port member is determined. When the port member status is in a first state, then the associated port member ID is used as a destination port to transmit to. When the port member state is in a second state, then a next entry in the port table is accessed to find a next available entry having a port member status that is in the first state and the corresponding port member ID of the port member state that is in the first state is used as a destination port to transmit to. The first state is UP and the second state is DOWN.

Abstract: A router apparatus for performing communication by switching a first and second line, the router apparatus includes: a setting unit which sets a first protection time until the first line is switched to the second line after a line failure in the first line is detected, and a second protection time until the second line is switched to the first line after recovery from the line failure in the first line is detected, to times corresponding to a quality state of the first line, respectively; and a line switching unit which switches the first line to the second line when the first protection time elapses and the line failure in the first line continues, or switches the second line to the first line when the second protection time elapses after the line failure in the first line is detected.

Abstract: A technique of operating a network node of a multicast communication network comprising a plurality of network nodes which are interconnected with each other by communication links is provided, wherein the network node is associate with a common source network node. A method implementation of the technique comprises: determining a first path which connects the network node to the common source network node along a primary network tree, and determining a second path which connects the network node to the common source network node along a secondary network tree, wherein the first path and the second path show redundancy with respect to each other; receiving, at the network node, multicast data from the common source network node via the first path; triggering, by the network node, reception of multicast data from the common source network node via the second path if the network node detects a failure of the first path (e.g., determines that no multicast data is received via the first path).

Abstract: Link identifiers such as VIDs, selected from a defined range of values, are locally assigned by each node on a link state protocol controlled Ethernet network to each of its links or adjacencies. The link identifiers are assigned by the nodes such that each link or adjacency at the node is uniquely identified by a different link identifier. A link state protocol adjacency notification mechanism or other flooding mechanism is used to disseminate the locally assigned link identifiers to other nodes on the link state protocol controlled Ethernet network. The link identifiers are added by the nodes to their topology databases to enable detour routes to be locally calculated by the nodes on the network in a distributed manner. Upon occurrence of a failure, the link identifiers are used to source route traffic around the failure so that traffic may continue to traverse the link state protocol controlled Ethernet network.

Abstract: Systems, methods, and apparatus for facilitating communications between an external controller and Fieldbus devices are described. A primary linking device in communication with the controller and one or more Fieldbus devices may be configured to direct the communication of a timing message to the controller and determine whether a response to the timing message has been received from the controller. Based upon the determination, the primary linking device may direct a switching of communications control to a secondary linking device.

Abstract: A method for controlling a control station (H1) includes the steps of performing wireless connection processing (204) with a terminal station (D1) and when a wireless connection is established, sending, to the wirelessly-connected terminal station (D1), a capture request signal (205) for causing the terminal station to capture a control signal (202) sent by another station (H2) and to return (207) information regarding the captured control signal.

Abstract: A computer network includes first and second Ethernet access domain networks, each of Ethernet access domain networks including a user-facing provider edge (u-PE) device, and a stack group of network-facing provider edge (n-PE) devices coupled with the u-PE device, the n-PE devices running a bidding protocol to select one of the n-PE devices as a primary n-PE device for a single pseudowire connection path between the first and second Ethernet access domain networks. 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. 37 CFR 1.72(b).

Abstract: Today, 100BaseT is commonly used in industrial Ethernet application. As a result of being in such an environment, Ethernet cables are subject to abuse, which can result in costly failures and repairs. Here, a system is provided that enables use of remaining and largely undamaged twisted-pairs within Ethernet cables to maintain 100BaseT connections without costly repairs and failures.

Abstract: A system for controlling packet forwarding through a dual-homed connection between first and second network domains, the dual-homed connection including two peer nodes connected to the first and second network domains. A sub-ring network is instantiated in the first network domain, and includes at least two nodes connected in a linear topology between a pair of end-nodes. Each end-node corresponds with a respective one of the peer nodes. A virtual link through the second network domain for conveys traffic of the sub-ring network between the peer nodes, and closes the sub-ring network to define a ring topology. Each of the nodes of the sub-ring network is controlled to forward packets of the sub-ring network in accordance with a ring network routing scheme.

Abstract: A path protection method that includes: establishing a point to multi-point (P2MP) tree spanning from a head node to a plurality of tail nodes, the P2MP tree providing a label switched path (LSP) from the head node to a particular tail node; identifying a first and a second pluralities of source-to-leaf (S2L) sub-LSPs for the LSP included within the P2MP tree, each corresponding pair of S2L sub-LSP in the first and second pluralities are path diverse; setting a first flag in a RSVP path message to designate the second plurality of S2L sub-LSPs as protecting respective S2L sub-LSPs in the first plurality at a baseline level of protection; setting a second flag to designate a subset of S2L sub-LSPs in the second plurality as protecting respective S2L sub-LSPs in the first plurality at an elevated level of protection; and transmitting the RSVP path message.

Abstract: A set of critical nodes or links is identified on the network and alternate forwarding state is pre-computed and disseminated within a node such that, upon failure of one of the critical nodes/links, a minimal trigger will cause the alternate forwarding state to be used to forward traffic on the routed Ethernet mesh network. In one embodiment rather than storing full tables of alternate forwarding state, only the changes to the forwarding state required by an identified failure is stored by the network nodes. Upon occurrence of a failure on the network, the identified failure is used to select the alternate forwarding state.

Abstract: A method for transmitting data in a layer two network having layer three routing capabilities includes transmitting, via a physical loopback, the data from a layer two switching component of a multi service platform to a layer three switching component of the multi service platform. The data specifies an initial routing path for the data that identifies a first layer two switch, and the method includes determining a new routing path for the data, the new routing path identifying a second layer two switch different than the first layer two switch. The method also includes updating the data to specify the new routing path, and transmitting, via the physical loopback, the data that specifies the new routing path from the layer three switching component to the layer two switching component.

Abstract: A connection between network nodes in a communication network is backed up. A failover switched path such as a label-switched path (LSP) is created starting at a first network node of a connection and ending at the second node of the connection, while bypassing the protected connection. In the event of connection failure, data is transmitted through the failover switched path (e.g., LSP). A network operator can selectively protect different types of data by using filters that bind one or more types of traffic received over one or more interfaces to different failover switched paths (LSPs).

Abstract: The present disclosure provides systems and methods for mesh restoration based on Associated Hop Designated Transit Lists (DTLs). The Associated Hop DTLs are calculated through a global restoration calculation (GRC) algorithm that can be run by a central controller in an offline manner. The restoration paths calculated by the GRC algorithm can then be pushed down to the originating nodes for each connection to utilize at the time of a given failure scenario. This GRC algorithm can be performed for each possible bundle failure in the network, where a bundle failure is determined by the set of all links which may fail together due to common shared risk, such as a common conduit or DWDM fiber. The globally calculated, contention free, restoration paths are then pushed down to each node in the network.

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

Abstract: A resilient load balancing method uses fixed paths and a fixed path-splitting strategy to enable ingress routers to efficiently reroute traffic after a failure. An off-line management system computes a set of fixed paths and a set of splitting ratios for routing demand from ingress routers to egress routers, with sufficient capacity to meet demands under each failure scenario. That data is then used by the ingress router to reroute demand after observing a failure.

Abstract: A data transmitter is provided. The data transmitter is configured to transmit reception data and copy data of the reception data to the outside via respective separate ports. The data transmitter includes an identification information attaching unit configured to attach, to the reception data, identification information identifying the reception data, a reception data copying unit configured to copy the reception data with the identification information attached thereto, a data calculation unit configured to perform the same calculation operation on the reception data with the identification data attached thereto and the copy data copied by the reception copying unit, and an identity determiner unit configured to determine whether the reception data with the identification data attached thereto is identical to the copy data, based on the identification data and the calculation results of the data calculation operation.

Abstract: A loss determining unit of a monitoring device calculates a receiving-time interval between a receiving time of data and the receiving time of immediately previous data. If the interval is a predetermined threshold or higher, the loss determining unit determines that “a loss is detected” and calculates the number of losses. If the number of losses is lower than the threshold, the loss determining unit determines that “no loss is detected”. A failure-section determining unit calculates the number of losses occurring in a first section. The failure-section determining unit calculates the number of losses occurring in a second section. If the loss is detected in the first section, the failure-section determining unit determines that a failure occurs in the first section. If the loss is detected in the second section, the failure-section determining unit determines that a failure occurs in the second section.

Abstract: An optical ring network has one or more working wavelengths and multiple protection wavelengths adapted to support the working wavelength(s). Routing tables may be used in network nodes to assign traffic of a failed working wavelength to a protection wavelength. The protection technique may be applied to networks employing, for example, Dense Wave Division Multiplexing (DWDM).

Abstract: A router is provided. The router includes a primary interface, a backup interface, a processor, and a memory. The primary interface and backup interface may be used to communicate with a network switch. The router may be configured to determine whether the primary interface is stable. The primary interface is stable when the primary interface may be used to exchange information with a network switch over a primary network segment. The router may be configured to activate the primary interface when the primary interface is determined to be stable. The router may also be configured to activate the backup interface when the primary interface is determined to be not stable. The backup interface may be activated for the exchange of information with the network switch.

Abstract: Techniques for computing a path for a local repair connection to be used to protect a connection traversing an original path from an ingress node to an egress node. The computed path originates at a node (start node) in the original path and terminates at another node (end node) in the original path that is downstream from the start node. A Constraint Shortest Path First (CSPF) algorithm may be used to compute the path. The computed path is such that it satisfies one or more constraints and does not traverse a path from a first node in the original path to a second node in the original path, wherein the first and second nodes are upstream from the start node in the original path and the second node is downstream from the first node in the original path. A local repair connection may then be signaled using the computed path.

Abstract: Multicast traffic is transferred, via routers, from a sender to receivers through a delivery tree that is determined based on a multicast routing protocol and includes delivery paths each communicably coupling the sender and one receiver. A router includes a multicast routing table used for transferring the multicast traffic through the delivery tree. The router generates delivery path information on first and second delivery paths each communicably coupling the sender and the router. Upon detecting a link failure on the first delivery path, the router performs delivery-path change processing that switches a first pair of interfaces along the first delivery path to a second pair of interfaces along the second delivery path without waiting for the multicast routing table being updated using the multicast protocol, and transmits a delivery-path change message to routers along the second delivery path so that the routers perform the delivery-path change processing.

Abstract: In an apparatus for receiving and forwarding data packets on a network, a network device includes a plurality of ports for coupling to the network and for transmitting packets to devices disposed in or coupled to the network. At least one processor configured to process packets received via the network processes packets by selectively forwarding processed packets to one or more of the ports. A plurality of queues are defined in a memory, each configured to store packets to be transmitted by ports in the plurality of ports. A queue manager is configured to selectively assign a subset of the plurality of queues to a subset of the plurality of ports.

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: A receiving apparatus in a wireless communication system that involves both data transmission using a virtual transmission path in which a plurality of wireless lines of which modulation method is variable are virtually consolidated into one, and time-division multiplex transmission, includes a releasing unit that releases, when a failure occurs in a current line used in the time-division multiplex transmission, one wireless line in the plurality of wireless lines constituting the virtual transmission path from the virtual transmission path; a demodulation unit that changes a modulation method used for demodulation of the one wireless line released from the virtual transmission path by the releasing unit to a modulation method used in the time-division multiplex transmission; and a switching unit that switches line connection from the current line in which the failure has occurred to the one wireless line of which modulation method has been changed by the demodulation unit.

Abstract: A full duplex/half duplex mismatch is detected by a full duplex/half duplex mismatch detecting apparatus connected through a network to a host. The loss rate of the transmission of a check messages is compared according to a sequential transmission pattern and the loss rate of the transmission of the check message according to divided transmission patterns by the full duplex/half duplex mismatch detecting apparatus, and if the loss rate of the transmission of the check messages according to the sequential transmission pattern is the larger, a full duplex/half duplex mismatch is determined to be present on the network path.

Abstract: The present invention discloses a method, an apparatus, and a communication system for protecting signaling transmission, relates to the communication field, and enables end-to-end signaling protection. In an embodiment of the present invention, a primary signaling path and at least one secondary signaling path are created between terminals; the transmission protocol of the primary signaling path is different from the transmission protocol of the secondary signaling path, and the secondary signaling path works instead when the primary signaling path is in an abnormal state. The embodiments of the present invention are primarily applied to communication systems, and in particular, to the communication systems that support multiple transmission modes, for example, WCDMA system that supports IP bearers.

Abstract: In a communication device for monitoring a network system where a frame is transferred, with a maintenance frame for maintenance and management, an input-output section inputs or outputs a frame. A failure detection section detects occurrence of a failure in the network system on the basis of the inputted frame. A setting section sets the communication device according to the detection of the failure so as to terminate or transfer a data frame inputted from the input-output section. A data frame control section controls whether to terminate or transfer the data frame, according to the setting of the data frame by the setting section. A maintenance frame control section controls whether to terminate or transfer the maintenance frame inputted from the input-output section, according to the setting of the data frame by the setting section.

Abstract: A base station apparatus performing communication through the use of a plurality of frequency bands and a mobile station apparatus wirelessly-connected to the base station apparatus, efficiently manage a radio link state of the frequency band in consideration of a cooperation relation between the plurality of frequency bands. The base station apparatus and the mobile station apparatus communicate with each other by aggregating a plurality of cells of different frequencies, the base station apparatus, in a case of configuring a plurality of cells of different frequencies to the mobile station apparatus, configures linkage information indicating a cooperation relation between an uplink and a downlink for each of the cells, and a timer for managing a state of the cells, and the mobile station apparatus simultaneously changes states of the uplink and the downlink of the cell upon timer being expiration, based on the linkage information for each the cell.

Abstract: The present disclosure relates to highly available communication networks, e.g., for industrial or utility applications such as substation automation. The devices are connected to two redundant lines through two independent transceivers and bus controllers, i.e. the physical layer and the link layer of the corresponding protocol stack is duplicated. For seamless operation, a sender sends frames simultaneously over both lines and a receiver accepts whichever frame of a pair comes first and ignores the late frame. An exemplary method is disclosed for discarding duplicate frames at the link layer without considering the higher protocol layers, based on a counter inserted in the frame and an algorithm for rejection, with a corresponding means to detect which frames operate according to the redundancy protocol.

Abstract: Aggregation Switches connected via a virtual fabric link (VFL) are each active and able to communicate via an inter-process communication (IPC) using an IPC Virtual Local Area Network (IPC VLAN). A sub-set of Customer-facing ports (CFPs) of each Aggregation Switch are coupled to the VFL and assigned to the IPC VLAN to enable communication therebetween.

Abstract: Providing protection to network traffic includes sending a Pseudowire protection configuration parameter for configuring a standby Pseudowire between a source node and a destination node, receiving a Pseudowire configuration acknowledgement indicating whether the Pseudowire protection configuration parameter has been accepted by the destination node, and in the event that the Pseudowire protection configuration parameter has been accepted by the destination node, using the standby Pseudowire, wherein the standby Pseudowire's configured based at least in part on the Pseudowire protection configuration parameter.

Abstract: Embodiments of the invention describe apparatus, systems and methods for creating a protection switching domain having a control virtual local area network (vlan), a first set of high priority protected data vlans, and a second set of lower priority protected data vlans. When a fault is detected at a ring network, indicating a failed link between adjacent nodes, said fault is communicated to a master node of the ring network via the control vlan. Embodiments of the invention allow a user to specify a priority for each of its domains on a given set of ring ports. The higher priority protected data domains are serviced to completion prior to servicing the lower priority protected data domains, ensuring that data traffic convergence time does not increase across these vlans.

Abstract: A first communication device detects a failure on a communication channel of a primary network. Based on the failure, the first communication device sends communications directed to a second communication device to a secondary network. A secondary network domain controller sends the communications to the primary network via a different communication channel. This can be done by looking at an identifier such as an IP address. This can also happen based on being able to communicate between the secondary network and the primary network via the different communication channel. The primary network then sends the communication to the second communication device. In addition, communications from the second communication device are routed in a similar manner to the first communication device. Sending the communications back into the primary network allows users to have access to features not provided by the secondary network.

Abstract: A method and computing device receives data packets on an upstream bonding group in full service mode, where the upstream bonding group includes a set of channels and each channel has a transmission quality. The method detects that a select channel in the set of channels is impaired when the transmission quality of the select channel is below a threshold value, and transitions the receiving of the data packets from full service mode to partial service mode by disabling data grant scheduling on the select channel. The method monitors the select channel using a spectrum management method while the receiving of the data packets is in partial service mode. The method transitions the receiving of the data packets from partial service mode to full service mode when a result from the spectrum management method indicates that the select channel can transmit data packets error free.

Abstract: In one embodiment, a reactive routing computer network may be partitioned into diverse logical topologies, and a source node may transmit route request (RREQ) messages toward a destination node on each logical topology. In response, the source node may receive route reply (RREP) messages indicating routes to the destination node in each logical topology. The source node may thus select a route for each logical topology to reach the destination node, accordingly. In another embodiment, if partitioned logical topologies do not produce two or more routes or as a standalone embodiment, the source node may transmit RREQ messages toward the destination node without any corresponding logical topology. The destination node receives RREQ messages, and two or more routes from the source node to the destination node may be determined (e.g., by the destination or source node) based on the received RREQ messages at the destination node and path selection criteria.

Abstract: A method for operating a network having a ring topology, in which a faulty connection between two stations of the network is detected by monitoring carrier signals. This method enables a faulty connection to be quickly detected in a network. Data may be advantageously rerouted in response to the detection.