Abstract: A method of finding a primary communication path in a mesh network, which would be at once a protected path having a fully guaranteed segmented node or node-link protection. The method comprises defining a required protection type and further selecting each specific path segment of the desired communication path based on initial user's requirements and topology information of the network. Each specific node path segment N for the communication path is selected upon ensuring that it can be protected in the network by a node backup path satisfying the initial user's requirements. Each specific link path segment L for the communication path is chosen if it can be protected in the network by a link backup path satisfying the initial user's requirements and if the node path segment N to which segment L leads cannot be protected by a suitable node backup path.

Abstract: A technique for controlling power of a network node in an optical mesh network, comprising: determining a number of optical paths ingressing or expected to ingress the node, determining capacity or expected capacity of each of the paths; calculating for each of the paths a virtual input power Pvirtual, based on estimation of relative capacity of a specific path with respect to total capacity of all the paths; applying to the network node a power control mechanism, while utilizing a corresponding virtual input power Pvirtual as input power of any of the paths.

Abstract: A method for allocating faults in a passive optical network (PON) by placing a number of passive unique optical correlators in a number of respective diagnostic points of the PON, each of the passive unique optical correlators being responsive to an optical diagnostic signal by returning a predetermined unique matching signal; by further transmitting the diagnostic optical signal in the PON towards the diagnostic points to receive upstream response signals from the correlators. Upon detecting presence or absence, in the received response signals, of a predetermined unique matching signal expected from a specific optical correlator, judging about a fault in proximity of the respective specific diagnostic point.

Abstract: A technique for performing a flushing process at a port of a network switch, where the flushing process comprises a flooding operation and an operation of relearning MAC addresses. In the method, these two operations are made independent, and the operation of relearning MAC addresses is started before termination of the flooding operation. An operation of forwarding packets to the relearned MAC addresses can be started before termination of the flooding operation.

Abstract: A method for recovery of a traffic flow being conducted via a communication line in a multi-layer communication network, the traffic flow comprising a Guaranteed traffic portion GT and a Best Effort traffic portion BET assigned to respective bandwidth resources of the line. The communication network comprising at least two network layers provided with respective traffic recovery mechanisms which utilize bandwidth resources such as time slots, wavelengths, physical links, logical links. The traffic flow may comprise traffic component(s) at different network layers, and the bandwidth resources of the traffic component(s) may be divided into GT and BET portions. The method comprises forming a shared pool of recovery resources, for all the layers in the line, from the bandwidth resources assigned to BET on all the layers. The method further comprises utilizing the shared pool of recovery resources for recovery of any of the traffic components of the traffic flow.

Abstract: A technique is proposed for performing add/drop operations in an OADM assembly serving an optical network and comprising an add unit and a drop unit. With respect to at least one optical channel assigned to an optical wavelength ?, the OADM assembly is capable of dropping the channel from the network via the drop unit as a first signal, and adding the channel to the network via the add unit as a second signal. According to the technique, the OADM assembly additionally comprises an authentication and control unit ACU for authenticating the at least one optical channel and controlling the OADM assembly. The ACU is authenticates the optical channel by comparing one or more components of the first signal with one or more components of the second signal serving as a reference, and based on the authentication result, makes decisions whether to allow or block the dropping and/or adding of the optical channel.

Abstract: A method for selecting a relation between a gain Gf of a Forward Raman Amplifier (FRA) at a transmitting end of a fiber optic transmission line and an optical signal to noise ratio (OSNR) at a receiving end of the fiber optic transmission line satisfying limitations for real long transmission lines. The method comprises selecting the relation using a regulation function ROSNR obtained either in the form of a simplified equation, or in the form of one or more linear approximations of the function for practical ranges of the FRA gain.

Abstract: A secured OTT architecture for Triple-Play services as well as for OTT based cellular service. Any access networks to which customers of the OTT based services belong, form a so-called last mile access segment which is less prone to security attacks than a public network such as the Internet. The customers' equipment (broadband CPEs, say in the form of modems or Femtocell CPEs) can be freed from securing traffic within the non-public access network, while an access node being a border node between the two networks aggregates the traffic from the access terminals and generates one or more secured communication tunnels via the public network for transmitting the aggregated traffic.

Abstract: A technique for exchanging LCAS control information between a first network element and a second network element interconnected by a bi-directional optical communication line, while conveying substantially unidirectional data traffic in the form of a virtual concatenated group (VCG) binary stream transmitted in a first direction via the bi-directional optical communication line, the technique comprising: —in the first direction, transmitting the LCAS control information via the bi-directional optical communication line in the VCG binary stream, by placing the information in one or more overhead bytes conventionally specified for the VCG binary stream, —in a second (opposite) direction, transmitting the LCAS control information in an existing binary stream non-related to the above-mentioned unidirectional data traffic; the existing binary stream should pass via a communication trail connecting the first network element and the second network element but not obligatory coinciding with the above-mentioned line;

Abstract: Technique for low cost delivery of a high bit rate electric signal via an optical network, by using a group of optical channels in the network for respectively delivering there-through a number of component electric signals of the high bit rate signal, The optical channels are respectively associated with different wavelengths, and each of the optical channels comprises optical elements suitable for conducting an optical signal having bandwidth significantly narrower than bandwidth of any of the component signals. The high bit rate electric signal is then successively restored from the optical signals delivered via the optical channels.

Abstract: Technique is proposed for managing total power consumption in an access network comprising two or more interface modules serving a plurality of subscriber lines, the technique comprises performing a study of real power consumption of the subscriber lines in the access network on a line-to-line basis, correlating results of the study with inventory information concerning allocation of the subscriber lines to the interface modules and power consumption ensured by said modules to the lines and, based on the correlation, assessing optimality of allocation of the subscriber lines to the interface modules.

Abstract: A method of multicast transmission in a communication network by using IGMP protocol, to a plurality of IGMP-equipped hosts serving end customers of the network, the method comprises:—using IGMP protocol to request receipt of information along a multicast channel, by a particular end customer;—adding the end customer to a multicast group including, upon adding said particular end customer, at least one of the end customers;—delivering information along the multicast channel to the end customers belonging to the multicast group, and in response to the request, ensuring for the particular end customer access to information delivered along the multicast channel by transmitting to that end customer access data, which includes: churning information indicative of a multicast churning key and/or service information, and/or a combination thereof.

Abstract: The invention proposes a method for handling ATM traffic comprising packets of AAL5 type composed of ATM cells, at a network node at VP-layer. The method comprises monitoring each of the cells incoming the node to obtain information at least on its VC-layer and VP-layer parameters, processing information on the mentioned parameters and registering the processed information concerning each of the cells in a statistical database to obtain statistical data with respect to at least the VC-layer and VP-layer parameters of the packets handled at the node.

Abstract: A technique for testing peer nodes in a multicast domain (such as an access network) interconnected with an Ethernet network via an Intermediate Bridge (IB), especially helpful when an individual MAC address of a destination peer node is unknown. The technique comprises a) issuing a Connectivity Fault Management (CFM) message from the Ethernet network, and introducing into the CFM message alternative destination data being different than the individual MAC address of the destination peer node; b) utilizing the alternative destination data, at the IB, for determining topological position or address of the destination peer node, and c) forwarding contents of the CFM message only to the destination peer node.

Abstract: Technology for detecting an optical data signal carried in a combined optical signal that comprises a carrier optical signal modulated by the optical data signal and also comprises ASE noise. The proposed optical data detector/receiver is provided with an SHG device adapted to generate a second harmonic optical signal of the carrier optical signal modulated by the data signal. In the signal, generated by the SHG, the ASE noise will be essentially reduced.

Abstract: The invention concerns shutting down and restarting optical amplifiers, such as Raman amplifiers, in an optical link, depending whether the optical amplifier is a transmitting side amplifier or a receiving side amplifier. For controlling the amplifiers, at least one diagnostic signal is to be transmitted via an auxiliary optical channel in the optical link, and a number of physical events simultaneously taking place are to be taken into account to conclude whether to shut down or to restart one of the optical amplifiers.

Abstract: A system for serving N optical communication lines by a redundant set of modules in an optical network; where the set of modules comprises N>1 main modules and one backup module, N optical splitters, 2N fiber connections and a control means. In the system, each of the N optical splitters is connected to two different modules of the set by two respective fiber connections out of the 2N connections, while each of the N optical splitters is also coupled to one of the N optical communication lines. The arrangement is such that the control means selectively activates/inactivates any of the fiber connections for respectively enabling/blocking transfer of data there-along; the control means thus ensures that each specific line of the N optical communication lines is always served by either one or another of two different modules.

Abstract: Technique for protecting different telecommunication services in an Ethernet network using two different loop avoiding traffic protection protocols, by concurrently utilizing the protocols in one and the same network on different loop free logical topologies of the network. The telecommunication services are preliminarily distributed in such a manner, that the services which can be better protected by one of the two protocols and the services better protectable by the other protocol, are carried via the different topologies.

Abstract: A technique for carrying out protection of data traffic in a multi-channel multi-section optical communications network by simultaneously using Optical Multiplexed Section (OMS) protection and Optical Channel (OCH) protection; the technique comprises selection of a working optical signal in an OCH protected optical channel, in case of a fault in a section of the network, by relying on an indication associated with OMS switching functionality that is required to overcome the mentioned fault.

Abstract: A method for estimating a bandwidth limiting penalty of a chain of bandpass optical filters in an optical telecommunication system. The method is advantageous for systems carrying an optical signal at a bit rate of about 10 Gb/s, wherein average bandwidth of the filters in the chain is of the same order of magnitude as bandwidth of the optical signal. The method comprises selecting a worst case filter, checking the system by testing and/or simulating it as being provided with the selected worst case filter instead of the chain of filters, and then judging about the bandwidth limiting penalty of the chain of filters based on results of the checking.