Abstract: For managing a traffic overload in a software defined network having an SDN controller, when an indication of a traffic overload is received, there are steps of identifying traffic flows which contribute to this, identifying nodes of the network controllable by the SDN controller and located along a path of the identified traffic flows before the location of the traffic overload. The SDN controller is used to control the identified nodes to control the identified traffic flows to reduce the traffic overload. By using the SDN controller to control the reduction compared to diverting suspicious traffic flows to a separate external security server, the extra network resources used for carrying the diverted traffic flows are not needed, the separate security server is not needed, and the risk of such diverted traffic flows themselves causing overloads is reduced. It can be applicable to a range of causes of overload, including denial of service attacks.

Abstract: A method of testing communications equipment comprises providing to the communications equipment a test traffic load which varies with time to a different level of test traffic load. The method also comprises measuring one or more parameter which characterizes the communications equipment in handling a transition of the test traffic load to the different level.

Abstract: A method of testing communications equipment comprises providing to the communications equipment a test traffic load which varies with time to a different level of test traffic load. The method also comprises measuring one or more parameter which characterizes the communications equipment in handling a transition of the test traffic load to the different level.

Abstract: A method of testing communications equipment comprises providing to the communications equipment a test traffic load which varies with time to a different level of test traffic load. The method also comprises measuring one or more parameter which characterizes the communications equipment in handling a transition of the test traffic load to the different level.

Abstract: A method in a first network entity which is capable of communicating over a plurality of communication links with a second network entity. The first network entity determines a level of transmit traffic transmitted over the plurality of communication links to the second network entity. The first network entity further determines a level of receive traffic received over the plurality of communication links from the second network entity. The first network entity further determines if the level of transmit traffic and/or the level of receive traffic meet one or more requirements for changing a number of active links of the communication links. If so, the first network entity changes the number of active links independently of the second network entity.

Abstract: For managing a traffic overload in a software defined network having an SDN controller, when an indication of a traffic overload is received, there are steps of identifying traffic flows which contribute to this, identifying nodes of the network controllable by the SDN controller and located along a path of the identified traffic flows before the location of the traffic overload. The SDN controller is used to control the identified nodes to control the identified traffic flows to reduce the traffic overload. By using the SDN controller to control the reduction compared to diverting suspicious traffic flows to a separate external security server, the extra network resources used for carrying the diverted traffic flows are not needed, the separate security server is not needed, and the risk of such diverted traffic flows themselves causing overloads is reduced. It can be applicable to a range of causes of overload, including denial of service attacks.

Abstract: A network management system (NMS) for a communications network has communications apparatus capable of being operated in different power consumption modes to provide different levels of performance, has a path computation apparatus configured to select paths for the traffic using the communications apparatus, based on information about traffic load in the network and on information about the power consumption modes of the communications apparatus of at least one of the nodes. A power mode controller is also provided for controlling the power consumption modes of the communications apparatus according to information about traffic load and according to information about the paths selected. By combining of path computation and the control of power consumption modes the overall power consumption of the network can be reduced. A slave power mode controller can be provided.

Abstract: A multiple output DC-DC converter comprises a transformer, a primary circuit, a plurality of secondary circuits, and a controller. The transformer has a primary and at least one secondary winding. The primary circuit connects to a DC power supply source and includes the primary winding of the transformer and a primary switch connected in series. The plurality of secondary circuits includes the at least one secondary winding of the transformer, wherein each secondary circuit provides a DC power supply output, and at least one of the secondary circuits has a secondary switch. The controller monitors an output signal of each secondary circuit and controls operation of the primary and secondary switches based on the monitored signals. The controller co-ordinates operation of the secondary switch with the primary switch, such that the primary switch and the secondary switch are switched on simultaneously, or with a controlled offset.

Abstract: An optical network comprising an optical network element comprising a first optical transmitter, a first controller, an optical receiver, a second optical transmitter, a second controller and optical receiver apparatus. Said first controller is arranged to control said first optical transmitter to generate and transmit a first optical signal in response no second optical signal being detected. Said first controller is arranged to iteratively generate and transmit said first optical signal at different wavelengths of a plurality of wavelengths until said second optical signal is detected, and is further arranged to subsequently maintain generation and transmission of said first optical signal at said wavelength at which said second optical signal is detected. Said second controller is arranged to control said second optical transmitter to generate and transmit said second optical signal following detection of said first optical signal by said optical receiver apparatus.

Abstract: According to embodiments of the present invention, a multi-lines cable simulator is provided which is able to simulate also crosstalk between lines. The multi-lines cable simulator is comprised in a modular unit configured to simulate increased number of lines by means adding further modular units. According to further embodiments, the modular unit is configured to also simulate increased line length by means of adding further modular units.

Abstract: A method in a first network entity which is capable of communicating over a plurality of communication links with a second network entity. The first network entity determines a level of transmit traffic transmitted over the plurality of communication links to the second network entity. The first network entity further determines a level of receive traffic received over the plurality of communication links from the second network entity. The first network entity further determines if the level of transmit traffic and/or the level of receive traffic meet one or more requirements for changing a number of active links of the communication links. If so, the first network entity changes the number of active links independently of the second network entity.

Abstract: An optical network comprising an optical network element comprising a first optical transmitter, a first controller, an optical receiver, a second optical transmitter, a second controller and optical receiver apparatus. Said first controller is arranged to control said first optical transmitter to generate and transmit a first optical signal in response no second optical signal being detected. Said first controller is arranged to iteratively generate and transmit said first optical signal at different wavelengths of a plurality of wavelengths until said second optical signal is detected, and is further arranged to subsequently maintain generation and transmission of said first optical signal at said wavelength at which said second optical signal is detected. Said second controller is arranged to control said second optical transmitter to generate and transmit said second optical signal following detection of said first optical signal by said optical receiver apparatus.

Abstract: A method of testing communications equipment comprises providing to the communications equipment a test traffic load which varies with time to a different level of test traffic load. The method also comprises measuring one or more parameter which characterizes the communications equipment in handling a transition of the test traffic load to the different level.

Abstract: An optical network (10) comprising an optical network element (12) comprising a first optical transmitter (14), a first controller (16), an optical receiver (18), a second optical transmitter (22), a second controller (24) and optical receiver apparatus (26). Said first controller is arranged to control said first optical transmitter to generate and transmit a first optical signal in response no second optical signal being detected. Said first controller is arranged to iteratively generate and transmit said first optical signal at different wavelengths of a plurality of wavelengths until said second optical signal is detected, and is further arranged to subsequently maintain generation and transmission of said first optical signal at said wavelength at which said second optical signal is detected. Said second controller is arranged to control said second optical transmitter to generate and transmit said second optical signal following detection of said first optical signal by said optical receiver apparatus.

Abstract: A network management system (NMS) for a communications network has communications apparatus capable of being operated in different power consumption modes to provide different levels of performance, has a path computation apparatus configured to select paths for the traffic using the communications apparatus, based on information about traffic load in the network and on information about the power consumption modes of the communications apparatus of at least one of the nodes. A power mode controller is also provided for controlling the power consumption modes of the communications apparatus according to information about traffic load and according to information about the paths selected. By combining of path computation and the control of power consumption modes the overall power consumption of the network can be reduced. A slave power mode controller can be provided.

Abstract: A multiple output DC-DC converter comprises a transformer, a primary circuit, a plurality of secondary circuits, and a controller. The transformer has a primary and at least one secondary winding. The primary circuit connects to a DC power supply source and includes the primary winding of the transformer and a primary switch connected in series. The plurality of secondary circuits includes the at least one secondary winding of the transformer, wherein each secondary circuit provides a DC power supply output, and at least one of the secondary circuits has a secondary switch. The controller monitors an output signal of each secondary circuit and controls operation of the primary and secondary switches based on the monitored signals. The controller co-ordinates operation of the secondary switch with the primary switch, such that the primary switch and the secondary switch are switched on simultaneously, or with a controlled offset.

Abstract: An optical network (1) comprising an optical network element (10) comprising a first optical transmitter (14), a first controller (16), a first optical receiver and a second optical receiver and a second optical network element (12). There is provided a transmission path (30) between said first optical network element and said second optical network element. Said first optical transmitter is arranged to generate and transmit a first optical signal. Said first controller is arranged to control said first optical transmitter to generate and transmit said first optical signal at a wavelength selected from a predetermined plurality of wavelengths. Said first optical receiver is arranged to detect a backscatter portion of said first optical signal returned to said first optical network element along said transmission path by distributing scattering.

Abstract: An optical access network comprises L wavelength division multiplexed access sub-networks. Each of the wavelength division multiplexed access sub-networks is arranged to use a set of wavelength channels. M optical line termination apparatus, each receive traffic from a respective operator network and output traffic on the wavelength channels. A wavelength routing apparatus comprises M sets of first ports and L second ports. Each set of first ports connects to a respective one of the optical line termination apparatus and each second port connects to an optical link of a respective one of the wavelength division multiplexed access sub-networks. The wavelength routing apparatus is arranged to route the set of wavelength channels between the sets of first ports and the second ports and to route different wavelength channels of the same wavelength to different ones of the second ports.

Abstract: A unit and a system for protection switching of line cards in a telecommunication system are described. A protection unit is connectable between communication lines and a line interface unit. The protection unit can be interconnected with other protection units to form a protection switching system. One protection unit in the protection switching system is connectable to a stand-by line card. The protection switching system is configured so that when protection switching is needed, the line signal is re-directed between the communication line for a failed line card and the stand-by line card via electrical connection elements.

Abstract: According to embodiments of the present invention, a multi-lines cable simulator is provided which is able to simulate also crosstalk between lines. The multi-lines cable simulator is comprised in a modular unit configured to simulate increased number of lines by means adding further modular units. According to further embodiments, the modular unit is configured to also simulate increased line length by means of adding further modular units.