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.

Abstract: A simple and effective all-optical system, producing a multilevel coded optical signal based on the M-ASK technology and by the minimized equipment. The novel all-optical modulation technique for optical M-ASK generation is based on nonlinear interaction between optical signals, say between N 2-ASK modulated pump signals having extinction ratio ER1 and a single 2-ASK modulated optical probe signal having extinction ratio ER2. According to the invention, a 4-ASK optical signal can be obtained using just a single binary modulated pump optical signal and a single binary modulated probe optical signal.

Abstract: A technique for forwarding downstream packets in a GPON comprising an OLT unit having a physical PON port connected to N Optical Network Termination (ONT) units by optical fibers. The physical PON port accommodates N individual virtual GEM ports terminated with the N ONT units (ONTs) which form N:1 service. The technique comprises assigning in the physical port of the OLT unit a virtual GEM port being a shared broadcast GEM port terminated with all the N ONTs of the N:1 service. Those downstream packets applied to the physical PON port, which would otherwise be flooded—such as broadcast packets or packets having unknown destination address—will now be forwarded only via the shared broadcast GEM port.

Abstract: A technique for securing data transmission via an optical communication line comprising an optical fiber extending between a first network element and a second network element; the technique comprises conveying a first optical signal carrying data via the optical fiber from the first network element towards the second network element at a predetermined optical wavelength, and conveying a second optical signal at the same predetermined optical wavelength via the same fiber in the opposite direction to create within the optical fiber a combined optical signal such that combination of the first and second optical signals is adapted to hamper an unauthorized non-intrusive extraction of the first optical signal from the combined optical signal.

Abstract: A technique is proposed for supporting a mobile communication session in a combined communications network comprising a mobile network and a non-mobile access network. In the mobile network, the mobile communication session is associated with a mobile number. The technique comprises: a) associating, in the non-mobile access network, the mobile number with a non-mobile device of the non-mobile network, b) providing an access device being in communication with a plurality of non-mobile devices of the non-mobile network and with a controller of a mobile network, operative to represent the non-mobile device of the plurality of non-mobile devices as having the mobile number; c) selectively conducting the mobile communication session either through a mobile device associated with the mobile number in the mobile network, or through the non-mobile device associated with the mobile number in the non-mobile network.

Abstract: A technique is described for controlling and optical network composed of network elements (NEs), with the aid of a network controller (NC) being in communication with the network elements. The technique includes collecting, by the network controller NC, information on the NEs therefrom, and, whenever a change in the network is requested, simulating within the NC operation of the network with the requested change and based on the collected information. The NC makes a decision on acceptability of the requested change, and may then cause implementation of the requested change in the network.

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 compensating undesired effects in optical links of an optical communication network, using adjustment modules suitable for inserting into optical links, preferably into the links incoming network nodes. Each of the adjustment modules serves for compensating two or more different physical effects accumulated in the optical link when transmitting an optical signal there-along. The module comprises at least two controllable blocks respectively comprising a variable gain optical amplifier VGA for selectively compensating power loss and a tunable dispersion compensation module TDCM for selectively compensating chromatic dispersion.

Abstract: For securing from invasion a group of network nodes in a multi-channel optical communication network, providing wavelength selective optical amplifiers WSOA in optical fiber links incoming network nodes of the group, and providing a network controller NC for holding and updating control information about optical channels allowed in specific optical fiber links incoming specific network nodes of the group, and for supplying each of the WSOAs with suitable control information concerning the incoming optical fiber links associated therewith. At each specific WSOA, in response to the received control information, blocking any incoming wavelength except for wavelengths assigned to the optical channels allowed in that specific incoming optical fiber link.

Abstract: Technology for combating loops in multi-domain networks, by assigning to network domains categories, at least such as “high/trusted” and “low/less trusted”, and by making a decision about relearning Forwarding Information Base FIB of any edge node interconnecting different network domains, utilizing the assigned categories.

Abstract: Technique for expediting a shutdown process in a computerized system, comprising a number of software modules MUC, a number of functional components and at least one user entity U. A user entity applies requests to a MUC and serves an access provider of the MUC for accessing the functional components. The method performs accelerated shutting down of the software module MUC, by the following steps: initiating shut down of the MUC (by a user entity U); making the MUC software module opaque so as to stop managing of the functional components; shutting down the software module MUC.

Abstract: A method is provided to enable providing broadband communication services to a subscriber having a number of devices connected to a regional gateway (e.g. CPE). The method comprises the steps of: carrying out an authentication process between at one of the subscriber's devices and a network server, upon authenticating the subscriber, downloading information associated with that subscriber to an access node. At the access node, designating a port for communications with the regional gateway, and based on identification of the subscriber, allowing the provisioning of broadband communication services to all of the subscriber's devices connected to regional gateway. When the subscriber's device used for the authentication process is disconnected, the system shall continue allowing the provisioning of the already allowed broadband communication services to the remaining devices that are still connected to the regional gateway.

Abstract: A method for protecting Ethernet data packets transmitted over SDH/SONET traffic in a ring-like optical network formed by a number of nodes, the method includes utilizing MS-SPRING/BLSR system for SDH/SONET traffic protection and, in case of one or more network failures that result in at least one isolated node in the network, the method comprises preventing initiation of a squelching algorithm of the MS-SPRING/BLSR system with respect to the SDH/SONET virtual containers carrying the data Ethernet packets, while ensuring that the standardized use of byte J1 is prevented with respect to the same SDH/SONET virtual containers carrying the Ethernet packets.

Abstract: Technique for interconnecting a first communication network and a second communication network, for example layer 2 Ethernet networks, which uses a fully or partially redundant dual homing configuration. The configuration includes: at least three network elements where at least two of them are peer elements belonging to the second network, and at least two traffic lines respectively associated with the peer elements and connecting the first and the second networks via the three network elements. The technique comprises establishing a bi-directional signaling between the peer elements and, based on the signaling information, deciding which traffic line should forward the traffic.

Abstract: A method for utilizing a Spanning Tree Protocol (STP) in an Ethernet network wherein a number of VLANs are defined and a plurality of Ethernet switching nodes (A, B, C D E, F,G H) are interconnected via their ports (A1, . . . ,H4) so that each of the ports is initially assigned to one or more VLANs, and each of the VLANs is intended to enable traffic between two or more edge ports (D3, B3). The method comprises a so-called pruning procedure initiated upon establishing a new STP topology (30) related to one or more VLANs. This procedure concerns a broadcast domain of at least one of the VLANs and is aimed at obtaining a sub-tree for each pruned VLAN in the new STP topology. The sub-tree is usually shrunk, bound by the edge ports assigned to the corresponding pruned VLAN, and thus eliminates broadcast traffic of the pruned VLAN to any Ethernet switch extending beyond the obtained sub-tree.

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.