Abstract: A connection policy for a communications network has a local connection policy indicating which paths between a given one of the nodes (computer A, router A, host 898) and others of the nodes (computers B, C, filters B1, B2, C1, C2, hosts 890, 892) are allowable paths, by a symbolic expression of ranges endpoint addresses and other local connection policies in respect of other nodes. It is implemented in a distributed manner by determining, for the given node, which of the allowable paths, are dual authorized as allowable by the other local connection policy relating to the other node at the other end of that path, by Boolean operations on the symbolic expressions. For a given message for a given path between two of the nodes having their own local connection policies, both of these nodes determine whether the given path is currently dual authorized. This can provide reassurance that changes in versions of the connection policy won't transiently open a risk of undetected unwanted communication.

Abstract: Embodiments including methods, systems, and apparatuses for distributing, processing, and reacting to path information distributed via a service-agnostic packet fabric for the purpose of enabling path selection are disclosed. By configuring two ingress line cards to send path quality words to each other via the switch fabric, compare the path quality words, and determine whether to transmit traffic to an egress line card via the switch fabric based on the comparison of the path quality words, the embodiments enable a central switch fabric to be unaware of the paths that it carries, and enable both ingress and egress bandwidth of the switch fabric to be sized according to the facilities for which it is terminating. The switch fabric does not need to support working and protection paths simultaneously in some embodiments, allowing it to be scaled appropriately to termination facilities.

Abstract: The techniques of this disclosure provide local protection for network traffic in multipoint label switched paths (LSPs) due to link or node failure using loop-free alternate (LFA) next hops. The techniques include establishing a vanilla or point-to-point (P2P) LSP with LFA next hops between routers of a multipoint LSP for use in the event of link or node failure in the multipoint LSP. Upon a failure, the multicast traffic is tunneled between the routers using the P2P LSP with LFA to an alternate next hop with an associated label stack. The techniques of this disclosure define the label stack as including a P2P LSP label as well as a multipoint LSP label. In this way, the P2P LSP with LFA may be used for fast reroute (FRR) of traffic in the multipoint LSP until a convergence process completes for a new multipoint branch of the multipoint LSP.

Abstract: A method of Path Computation Element (PCE) Communication Protocol (PCEP) communication includes sending, to a path computation element (PCE), a request to compute a backup ingress node for a Point-to-Multipoint (P2MP) Label Switched Path (LSP) in a network, and receiving, from the PCE, the backup ingress node for the P2MP LSP in accordance with the request.

Abstract: A method is implemented in a network element for modifying the characteristics of tree construction for use in virtual network connectivity in a network that includes the network element. A virtual network is associated with a set of virtual network attachment points that are mapped to network elements in a topology of the network where the virtual network is individually associated with an equal cost tree (ECT) set. The method generates individual ECT sets to interconnect sets of virtual network attachment points for connectivity establishment and maintenance of the connectivity in the network. The method modifies link metrics across the topology of the network to be used for computing an ECT set to bias a tie-breaking process for selecting between equal cost paths toward either producing minimal cost shortest path multicast trees or maximizing unicast path diversity in the multiple ECT sets that are generated.

Abstract: Provided is a failure recovery method in a non-revertive mode of an Ethernet ring network. In an Ethernet ring network, link priorities between nodes or node priorities are determined based on media access control (MAC) addresses and the nodes having blocked ports are determined after failures are recovered from based on the priorities so that the blocked ports can be distributed.

Abstract: A system and method for traffic polarization during failures includes a communication network cluster including a first network switching unit configured to communicate with a first network node via a first network link and a second network node via a second network link, a second network switching unit configured to communicate with the first network node via a third network link and the second network node via a fourth network link, and a first intra-cluster link coupling the first network switching unit to the second network switching unit. The second network switching unit is further configured to respond to a failure in the fourth network link by broadcasting a route withdrawal message to the first network switching unit and the first network node. The first network switching unit is configured to accept rerouted network traffic from the first network node via the first network link resulting from the route withdrawal message.

Abstract: Embodiments generally disclosed herein include methods and systems for calculating incremental network costs between logical city pairs in a network (each city pair being in communication across the network via one or more physical links). For example, the method includes a cost analyzer that, for each physical link in the network, determines a steady state capacity allocation associated with each city pair in the network and, in the same vein, determines a restoration capacity allocation associated with each city pair in the network. The cost analyzer is capable of calculating an incremental cost per unit of traffic for a given city pair based on: i) the steady state capacity allocation and a restoration capacity allocation associated with a given city pair, as compared to, ii) the aggregate steady state capacity allocations and restoration capacity allocations associated with each city pair in the network.

Abstract: A chassis type switch is provided which can shorten a time required for switching-over to a backup route when a failure has occurred in a line card. In a chassis type switch including a plurality of line cards within a chassis, the switch further includes a failure detection unit for detecting a failure in each of the plural line cards, and a forced flooding processing unit included in each of the plural line cards and operating such that when, in trying to transfer a received unicast frame to another line card, a failure is detected in the relevant line card at a transfer destination, the received unicast frame is forcibly transferred to all ports of the own line card other than a reception port thereof and to all other line cards.

Abstract: In one embodiment, a packet switching device determines backup forwarding paths based on route distinguisher correlation values. A route distinguisher correlation value is some value associated with multiple routes, which allows a packet switching device to consider routes associated with a same route distinguisher correlation value, but having different route distinguishers and a same prefix to be considered as going to a same destination. Examples of route distinguisher correlation value used in one embodiment include, but are not limited to: scalar values, a route distinguisher of a different route, a virtual private network associated with a different route; a route target associated with the a different route; or a Border Gateway Protocol (BGP) Next-hop address associated with a different route.

Abstract: The disclosure provides a method and a device for feeding back Acknowledgment (ACK) information during switching of backhaul link subframe configuration, and the method includes during the switching of the backhaul link subframe configuration, if Uplink (UL) ACK/Negative ACK (NACK) information, which corresponds to a last transmission before the switching of one or more Downlink (DL) Hybrid Automatic Repeat Request (HARQ) transmissions, is not fed back on a UL subframe which is before the switching, feeding back the ACK/NACK information on an available UL subframe which is after the switching since Nms after the last transmission, wherein N is an integer. The disclosure achieves the effect of correctly feeding back the ACK information during switching of the backhaul link subframe configuration.

Abstract: The disclosure discloses a path switch-back method and apparatus in a transport network, belongs to the field of communications, and is used for avoiding the problem that signals can not be switched back to a working path from a protection path when the links in two directions of the working path between nodes in the transport network are restored from fault simultaneously. The path switch-back method in a transport network provided by the disclosure includes: a local node determines two failed links on the working path between an opposite node and itself are restored to normal simultaneously (S101); the local node enters a Wait To Restore (WTR) state (S102); and the local node switches signals back to the working path when the WTR state ends (S103). The disclosure is used for realizing that signals are switched back to the working path from the protection path when the links in two directions of the working path between nodes in the transport network are restored from fault simultaneously.

Abstract: A method implemented by a network topology design system, the network topology design system including a processing device. The method to determine placement of a controller within a network with a split architecture where control plane components of the split architecture network are executed by a controller and the control plane components are separate from data plane components of the split architecture network. The placement of the controller is selected to minimize disruption of the split architecture network caused by a link failure, a switch failure or a connectivity loss between the controller and the data plane components.

Abstract: An aspect includes protecting a former primary volume in a synchronous replication relationship. A swap between a primary volume at a first site and a secondary volume at a second site is initiated such that the secondary volume becomes a new primary volume and the primary volume becomes the former primary volume. A fenced state is set as active for the former primary volume. The former primary volume is configured as a fenced volume based on the fenced state being active. Read and write access to the fenced volume is blocked while the fenced state is active.

Abstract: RF signal amplifiers are provided that include an RF input port, a switching device having an input that is coupled to the RF input port, a first output and a second output, a first diplexer having an input that is coupled to both the first output of the switching device and the second output of the switching device, and a first RF output port that is coupled to an output of the first diplexer. These amplifiers further include an attenuator that is coupled between the second output of the switching device and the input of the first diplexer.

Abstract: An improved system and method for transmitting Operations, Administration, and Maintenance, OAM, messages on in a redundancy path are provided. For each OAM function on a service instance of a redundancy path “17 comprising one primary path and one secondary path “17 only one OAM endpoint is created. The OAM endpoint can transmit packets over both the primary and secondary paths. The OAM endpoint contains an index to the primary path and a redundancy index which is used to lookup into a redundancy table. Each entry in the redundancy table indicates whether the primary path or the secondary path is active. OAM packets are transmitted on the active path (i.e., primary or secondary). When a switchover between the redundant paths is required (i.e., when a failure or its correction is detected on the primary path), the corresponding redundancy table entry is changed to implement the switchover. In one embodiment, PW OAM over protected LSP is implemented in an MPLS or MPLS-TP network.

Abstract: A method for maintaining a bridging network communication path table is presented and includes determining a failed communication link between a first bridge computer and a second bridge computer in the bridging network; identifying, in the communication path table, a first path that includes the failed communication link; and indicating that the first path is not active.

Abstract: Various systems and methods for performing bit indexed explicit replication (BIER). For example, one method involves receiving a packet at a node. The packet includes a bit string includes information identifying a plurality of destinations. The node selects an entry in a bit indexed forwarding table (BIFT). The BIFT includes both a primary path entry and a backup path entry. The node forwards the packet based on information in the entry.

Abstract: A pluggable transceiver is provided for achieving a redundant connection in a communication network when inserted in a communication network node of the communication network. The pluggable transceiver is connected to a first cable on a first input and is directly connected to two or more data-plane ports when inserted. The pluggable transceiver comprises a converter to receive incoming data in a first representation and convert the incoming data from the first representation into a second representation, and a distributor to distribute the incoming data to a first data-plane port among the two or more data-plane ports in the second representation. The pluggable transceiver comprises a first selector to select the first data-plane port and receive outgoing data from the first data-plane port in the second representation, where the first data-plane port is active.

Abstract: A system for distributing network traffic among direct hardware access datapaths, comprising: a processor; one or more activated PNICs; a host operating system; and a virtual machine (VM). Each activated PNIC sends and receives data packets over a network. Each activated PNIC is configured with a virtual function. The VM includes a VNIC and a virtual link aggregator configured to maintain a list identifying each activated PNIC. Virtual function mappings for the VM associate the VM with virtual functions for the activated PNICs. The virtual link aggregator selects the first activated PNIC for servicing a network connection and determines a virtual function for the first activated PNIC. The VNIC for the first activated PNIC uses the virtual function to directly transfer network traffic for the network connection between the VM and the first activated PNIC.

Abstract: A network layout between network elements and routers using network redundancy to improve reliability of network communication is disclosed. Upon detecting a link failure associated with a primary link between an access switch and a primary router by the access switch via a connectivity verification protocol, the access switch sends a message to the primary router indicating connection defect via the connectivity verification protocol such as IEEE 802.1ag standard. After enabling protection switching mechanism to activate a secondary link between the access switch and a backup router for network communication, routing data streams are routed between the access switch and the router via the secondary link. In one aspect, the protection switching mechanism is operated in accordance with G.8031 under International Telecommunication Union (“ITU”) standard.

Abstract: A hierarchical structure network of devices is formed. A group of devices may be grouped together to form a domain. A plurality of domains formed in a hierarchical structure forms a hierarchical network. Traffic flow topology may be updated only within the same domain that topology changes. In one embodiment, traffic flow topology is updated only in a parent domain and a child domain when the status of a link connecting the two domain changes. Thus, other domains within the network have no need to update the traffic flow topology and remain agnostic to the traffic flow updates. Thus, responsiveness of the network to topology changes is improved. Multiple links may each carry traffic if multiple links exist between nodes. As such, a network of robust redundant interconnections with active links is formed that react quickly to network topology changes and that uses the interconnection links in an efficient manner.

Abstract: Failover of VPN traffic between MPLS tunnels is accelerated by determining a main and a standby MPLS tunnel for each VPN and passing both the main and standby MPLS tunnel information to the forwarding plane of a network element configured to implement the VPN. In the event of failover of a main MPLS tunnel interface, the forwarding plane is instructed to use the standby MPLS tunnel instead of the main MPLS tunnel. Since the standby MPLS tunnel has already been determined, and information associated with the standby MPLS tunnel has already been provided to the forwarding plane, it is not necessary to recompute a new MPLS tunnel or reprogram the forwarding plane using the new MPLS tunnel information. By removing control plane operations and control plane-forwarding plane interaction from the handling of failovers, the failover recovery time may be accelerated, to thereby enable VPN connections to handle time sensitive traffic.

Abstract: Disclosed are a method and node for a service to occupy protection resources in shared protection, including: when receiving a command or service state information, a node responding to the command or service state and allocating protection resources to a corresponding service in accordance with a priority order of a first-level manual command, a service signal failure, a service signal degradation and a second-level manual command. By integrating priorities of the manual command and the service state, the embodiments of the present document formulate a set of unified priority rules, reducing the information stored on nodes in a mesh network, and simplifying the processing procedure of the mesh network.

Abstract: Network repeaters which each implement a redundant switching function previously grasp connection states of ports of a network system by using an inquiry frame and an exchange frame. At the time when a line is broken, when actively confirming a state of a port connected to a port in which a line is broken via a downstream device, the network repeaters each grasp that which portion of the line is broken and determine whether a switchover is required. Through the process, the network repeaters each prevent a useless switchover such as switching-back immediately after the switchover, and at the same time since a mechanism of waiting for a given length of times is not required, they each perform a fast switchover.

Abstract: Embodiments of the present invention provide a method, an apparatus, and a system for switching a communication path. The method for switching a communication path includes: receiving, by an access network device, a data packet for implementing a communication service between a terminal and a first media source; learning, by the access network device, according to the data packet, that a local exchange path between the terminal and the first media source is unavailable; and transferring, by the access network device, the data packet via a detour path, where the data packet is also used by a channel control device on the detour path to control the terminal to disconnect from the detour path and establish a local exchange path between the terminal and a second media source, and where the second media source is in coverage of an access network device currently providing a service for the terminal.

Abstract: In an example of the invention, network devices are classified into areas. Each of the areas includes edge nodes. A network management apparatus retains fault information including values each indicating whether or not a fault has occurred in each of the areas, retains detour path information including values indicating edge nodes, values indicating alternative areas to the areas and priorities assigned to the alternative areas, identifies, when determined that a fault has occurred in a first area based on the fault information, an alternative area to the first area based on the detour path information, determines, when determined that the fault has not occurred in the identified alternative area, the identified alternative area as a second area through which the active path passes, determines two edge nodes included in the second area, and detect network devices through which the active path passes between the two edge nodes.

Abstract: A system and method is disclosed that assures component circuits transported in aggregated circuits restore correctly after an aggregated circuit fault. The system and method implements component circuit tail segment integrity checks whenever an aggregated circuit is restored in a higher level of a network hierarchy. Switches at both ends of an aggregated circuit perform circuit integrity checks of the tail segments of every component circuit. A failure of the component circuit integrity check on any component circuit causes that component circuit to be released and restored end-to-end.

Abstract: Embodiments of an evolved Node B (eNB) and methods for radio link failure handling for dual connectivity are generally described herein. A method performed by circuitry of a User Equipment (UE) may include connecting, at a UE, to a Master eNB (MeNB) and connecting to a Secondary eNB (SeNB). The method may include determining, at the UE, that one of the connections has a Radio Link Failure and determining at the UE, that the other of the connections remains connected to the UE. The method may include refraining from initiating a Radio Resource Control (RRC) re-establishment procedure while at least one of the connections does not have a radio link failure.

Abstract: In general, techniques are provided for receiving a first control plane message that indicates the reachability of the second PE network device as a designated forwarder in an Ethernet segment. The techniques include receiving a second control plane message comprising information that indicates, in the event of a network failure at the second PE router, that the third PE network device of the plurality of PE network devices is the designated forwarder in the layer two segment. The techniques also include forwarding layer two frames to the second PE network device identified as the designated forwarder in the layer two segment; and responsive to determining a network failure at the second PE network device, configuring, based at least in part on the second control plane message, a forwarding plane of the first PE network device to forward layer two frames to the third PE network device as the designated forwarder.

Abstract: Multiple redundant sources for a datastream can be established in a network, where the redundant sources are configured with the same source address. One of the redundant sources provides the datastream to a receiver of a multicast group. If the redundant source fails, another redundant source can be used in its place, ensuring the receiver continues to receive the datastream. A routing element coupled to a redundant source monitors the redundant source for failure and informs the rest of the network of the status of the coupled redundant source. The routing element can inform other routing elements of the status by advertising or withdrawing a route that reaches the coupled redundant source, which the other routing elements can use to update their routing tables.

Abstract: Provided is a relay system having a first node and a second node, and a third node and a fourth node provided opposing thereto with connected by VLAN paths, in which the first node notifies, via a second VLAN path, the fourth node of the APS packet in which a state of a first group is stored. The third node notifies, via a third VLAN path, the second node of the APS packet in which a state of a second group is stored. The second node and the fourth node use a fourth VLAN path and exchange the state of the first group and the state of the second group, and, when the states of the first group and the second group are SF-W of a first VLAN path and the self apparatus is master, switch the first VLAN path to the second VLAN path or the third VLAN path.

Abstract: In one embodiment, a primary bidirectional LSP is established between an originating LSP packet switching device and a destination LSP packet switching device through an intermediate packet switching device. A corresponding backup LSP is also established. The originating LSP packet switching device sends a particular label switched packet to the destination LSP packet switching device over the primary bidirectional LSP. An intermediate packet switching device sends the particular label switched packet back to the originating LSP packet switching device over the primary bidirectional LSP in response to an error condition identified as affecting the primary bidirectional LSP towards the destination LSP packet switching device. The originating LSP packet switching device receives the particular label switched packet and sends it to the destination packet switching device over the backup LSP.

Abstract: A method may include: (i) in response to clearing of a fault on a working path of a protection switching group to which a first network element is interfaced: (a) transitioning, by the first network element, its state to a first state in which a protection path of the protection switching group is active; and (b) initiating, by the first network element, a wait to restore timer, the wait to restore timer having a duration such that upon expiration of the timer, the first network element is configured to switch the working path to active; and (ii) in response to receiving a message from a second network element interfaced to the protection switching group indicating that a failure has occurred on the working path: (a) maintaining, by the first network element, its state in the first state; and (b) continuing, by the first network element, the wait to restore timer.

Abstract: A device-level redundancy protection method and system based on Link Aggregation Control Protocol (LACP), wherein the method includes: configuring same parameters for the Link Aggregation Group (LAG) on a first device (LAGP1) and the LAG on a second device (LAGP2), and transmitting an LACP Data Unit (LACPDU) message carrying the parameters to the LAG on a customer edge (LAGC). After receiving the LACPDU message, the LAGC adds physical links respectively connected with the LAGP1 and the LAGP2 into the same Aggregator on the customer edge (AGGC). The LAGP1 and the LAGP2 respectively add physical links connected with the LAGC into the Aggregator of themselves to form a virtual Aggregator (AGGV). The customer edge performs message interactions with a server via the AGGC and AGGV.

Abstract: Systems and methods provide remote performance monitoring and testing to a cell site in a cellular communications network. The systems and methods include a network management center having remote monitoring and testing capabilities utilizing an intelligent customer service unit that traps and makes available alarm information on the transport link.

Abstract: The invention discloses a system, a method and an apparatus for optical network protection. The system includes: an output control apparatus for obtaining protection mode information configured by a system and controlling an input signal to be output from a set line corresponding to said protection mode information; and a detection control apparatus for detecting powers of signals transmitted on an active line and on a standby line, if it is determined that the active line is abnormal and the standby line is normal according to detection results, then controlling the input signal to be output from a protection line corresponding to the protection mode information; if it is determined that the active line is normal, or that the active line and the standby line are abnormal according to the detection result, then controlling the input signal to be output from a set line corresponding to the protection mode information.

Abstract: An example method includes creating a plurality of redundant, non-looping paths to a plurality of switches, and providing information to the plurality of switches about the plurality of redundant, non-looping paths. The method further comprises assigning each of a plurality of clients to one of the plurality of redundant, non-looping paths, and providing information to the plurality of switches about which of the plurality of redundant, non-looping paths each client of the plurality of clients is assigned to. Then, in response to receiving a packet from a client of the plurality of clients, the method comprises transmitting the packet on one of the plurality of redundant, non-looping paths to one of the plurality of switches based at least in part on which of the plurality of redundant, non-looping paths the client is assigned to.

Abstract: A device receives packets of an application flow, and inspects one or more of the packets of the application flow. The device determines, based on the inspection of the one or more packets, a service graph of feature peers for the packets of the application flow. The feature peers are associated with a network and the service graph includes an ordered set of the feature peers. The device creates a representation of the service graph. The representation includes an ordered set of feature elements that represent the feature peers of the service graph. The device provides the representation of the service graph to a controller device, and the controller device configures, based on the representation, the network with the service graph so that the packets of the application flow traverse the service graph.

Abstract: A method implemented by an apparatus for providing spare capacity allocation (SCA) for dual link failures in a network. The SCA scheme computes the SCA for each of a plurality of flows in the network for a plurality of primary backup paths corresponding to a plurality of disjoint working paths for the flows using a first integer linear programming (ILP) model. The SCA scheme further computes the SCA for each of the flows for a plurality of secondary backup paths corresponding to the disjoint working paths and the primary backup paths using a second ILP model and the computed spare capacity information for the primary backup paths. The SCA scheme further aggregates the computed SCA for the primary backup paths and the secondary backup paths for all the flows.

Abstract: A computing network, including: a plurality of peer computing devices including code, which when executed by a peer computing device causes the executing peer computing device to cooperate with at least one other of the peer computing devices; at least one server including code, which when executed by the at least one server locates at least one of the peer computing devices; and at least one mediator including code, which when executed by the at least on mediator collects charging information from at least some of the peer computing devices; wherein, the peer computing devices, at least one sever and at least one mediator are communicatively coupled via an at least carrier-grade telecommunications network being suitable for enhancing cooperation among the cooperating ones of the peer computing devices relative to best-efforts communications among the cooperating ones of the peer computing devices.

Abstract: Systems, methods, and tangible computer-readable media are described for network routing of traffic. The system includes a source node for multicast traffic assignment across multiple networks. The source node chooses a first node and at least one different node for transmitting a message, the message to be transmitted from the source node to the first node, then to the at least one different node, then to a destination node.

Abstract: A system, method and apparatus for adapting operation of a router configured to receive commonly sourced traffic via primary and secondary Upstream Multicast Hop (UMH) links, wherein the secondary path is cached for a predetermined period of time to avoid data loss upon restoration of the primary path.

Abstract: Technology for reducing packet transmissions is disclosed. A master evolved node B (MeNB) configured for dual connectivity can receive one or more acknowledgements (ACKs) from a user equipment (UE) indicating packets that were successfully received at the UE from a secondary evolved node B (SeNB). The MeNB can receive, from the SeNB, packet delivery information for the SeNB. The MeNB can receive an indication from the SeNB of an air-interface connection loss between the SeNB and the UE. The MeNB can identify remaining packets that were not sent from the SeNB to the UE based, in part, on the ACKs received from the UE and the packet delivery information received from the SeNB, wherein the remaining packets are not sent to the UE due to the connection loss between the SeNB and the UE. The MeNB can send the remaining packets from the MeNB to the UE.

Abstract: A packet switched communication system to support hitless protection includes a packet processor; a traffic manager with a buffer sized to compensate a maximum skew of each hitless path pair of a working path and a protecting path; and a hitless processor positioned between the packet processor and the traffic manager, wherein an interface between hitless processor and traffic manager has flow control to start or stop (XON/XOFF) traffic.

Abstract: An Ethernet backbone network system for a vehicle and a method for controlling a fail safe of the Ethernet backbone network system enable high-speed and large-capacity data transmission between integrated control modules mounted in the vehicle, such that communication can be maintained through another alternative communication line when an error occurs in a specific communication line. The Ethernet backbone network system enables various kinds of integrated control modules mounted in the vehicle to perform large-capacity and high-speed communications, based on Ethernet communication, by connecting domain gateways of the integrated control modules through an Ethernet backbone network, and provides a fast fail-safe function so that domain gateways can perform communications through another communication line when an error occurs in a communication line between the domain gateways.

Abstract: A method of and a device for enabling load balancing for Multiprotocol Label Switching Transport Profile (MPLS-TP) are provided. The method is applied to a process of transmitting data between two Provider Edge (PE) devices that adopt a protection mechanism of primary and backup tunnels. The method comprises allocating, by a source PE device located at a head node of a tunnel, traffic to each of the primary and backup tunnels in a current transmission period based on transmission performance information about each of the primary and backup tunnels in a previous transmission period fed back by a destination PE device located at a tail node of the tunnel, when a set transmission period comes; and obtaining, by said source PE device, the traffic allocated to each of the tunnels and transmitting data to the destination PE device via the corresponding tunnels.

Abstract: Methods and apparatus' of determining radio link quality are disclosed. According to various implementations, a user equipment detects an out-of-synchronization condition corresponding to a first control channel, and monitors a second control channel in response to the detecting the out-of synchronization condition.

Abstract: In a communications network, a recovery segment is used to reroute a recoverable part of a path set up along an original route along links between nodes. When a defect is detected in the original route of the path, but is undetectable by nodes within the recoverable part, a reroute message is sent (5) from outside the recoverable part to an end node (N2,N4) of the recoverable part. This prompts the rerouting of the recoverable part over the recovery segment. Thus segment recovery becomes possible for these defects which cannot be detected at nodes in the segment. This extends the applicability of benefits of segment recovery such as reduced resources devoted to recovery, and flexibility to choose which parts of paths to protect. The end node can send a notify message beforehand, to request (3) notification of the defect as the reroute message.

Abstract: A wireless communication method for a transmission apparatus that transmits an OFDM (orthogonal frequency division multiplexing) signal using a communication band, which comprises a plurality of subcarrier groups each including a plurality of subcarriers. The method includes specifying which subcarrier group and how many subcarriers are to be used to transmit the OFDM signal, determining a configuration of a transmission frame, generating the OFDM signal by mapping data symbols according to the determined configuration of the transmission frame, and transmitting the generated OFDM signal.