Abstract: A connection-oriented network (5) has a plurality of connections terminated at a first node (N6). A recovery group (A) is configured at the first node (N6) comprising at least two of the plurality of connections (LSP1-6, LSP2-6, LSP3-6, LSP4-6). Fault detection is performed over each of the connections in the recovery group (A) and the node determines if at least one recovery group fault condition is met, based on the results of the fault detections performed over the connections in the recovery-group (A). When the at least one recovery group fault condition is met, the node causes traffic on the plurality of connections in the recovery group (A) to be transferred to backup paths. When the at least one recovery group fault condition is not met, and a fault has been detected on a connection in the recovery group (A), the node causes traffic to be transferred from that connection to a backup path.

Abstract: A node (110) for an MPLS telecommunications network has interfaces (100) for OAM information exchange relating to a path for data traffic, between first and second other nodes each operating according to different OAM state machines for OAM information exchange. An OAM state machine mapper (120) maps the states of either of the different OAM state machines of the first and second other nodes into states recognised by the other of the different OAM state machines. OAM information exchange is according to either the first or the second OAM state machine and according to states mapped from the other of the OAM state machines, to support the path for data traffic through the node. By such mapping of the different states OAM information can be exchanged across corresponding boundaries and so paths no longer need to be terminated at the boundary to enable end to end operations.

Abstract: Method of re-routing traffic in a communications network (1) in the event of a fault (3) on a path across the network, the method comprising, determining whether a first node (4), located between the fault and a network ingress node (6), is capable of switching traffic to an alternative path which avoids the fault, and if the first node is determined to be not so capable, then determining whether a second node (8), located upstream of the first node, is capable of switching traffic to an alternative path which avoids the fault.

Abstract: There is provided method and apparatus for transferring data packets between a first network and a second network using a node arrangement. The node arrangement has at least two primary nodes connected to the second network. Each primary node is connected to the first network using a respective first port and to a secondary node coupled to the second network using respective second ports. The second ports are arranged into respective link aggregation groups. The primary nodes are connected by respective inter-node ports. The method comprises the step of determining a service identifier associated with a packet received at a said primary node from the first network. The method comprises the further step of switching the packet to the second network using the respective second ports or to the other primary node using the inter-node port dependent on a service identifier associated with said packet.

Abstract: A telecommunication network comprising a plurality of nodes including a content source (2) and at least one content receiver (3), the content source and the or each content receiver being connected via at least one switch node (4, 5, 6), and wherein the content source (2) is adapted to provide content that is associated with a multicast address to the at least one content receiver (3) using multicast communication. The network further comprises a content bandwidth indication generator node (3, 6, 7), the generator node being adapted to include an indication of the bandwidth requirement of the content supplied by the content source (2) along with the corresponding multicast address within a multicast protocol message (20, 60). At least one of the switch nodes (4, 5, 6) is adapted to extract said indication from the multicast protocol message and control the flow of content in response to said indication of the bandwidth requirement.

Abstract: Network interconnection apparatus comprising a platform with interface ports for network interconnection and comprising in turn a first series and a second series of interface port cards and an interconnection unit for commanded interconnection at least between the cards of the first and second series and between cards of the first series. The cards of the first series have their own associated MAC address tables for addressing traffic between ports through the interconnection unit. Each entry of the table has an age field defining in time the age of the entry. The content of the age field is periodically verified and if it reaches a preset maximum figure the entry is updated on the basis of the content of the age field by a corresponding entry in the table of another card of the first series and associated therewith by the information in the entry to be updated. If the content of the age field of the corresponding entry is also a maximum figure, both the entries can be deleted.

Abstract: An apparatus and a method are described in which a flow of packets is distributed in several separate flows over several links (12) forming a logically aggregated link (11). The flow outgoing from each physical link is sent to its own policer (18) which applies to said flow a traffic policing algorithm with the policers being interconnected to exchange algorithm control parameter modification information to fit them in among the various policers while allowing for the control parameters of the others so that a distributed policer (15) is realized.

Abstract: Network interconnection apparatus (10) comprising a platform with interface ports (12, 14) for network interconnection and comprising in turn a first series (11) and a second series (13) of interface port cards and an interconnection unit (15) for commanded interconnection at least between the cards of the first and second series and between cards of the first series. The cards (11) of the first series have their own associated MAC address tables (16) for addressing traffic between ports through the interconnection unit. Each entry of the table has an age field defining in time the age of the entry. The content of the age field is periodically verified and if it reaches a preset maximum figure the entry is updated on the basis of the content of the age field by a corresponding entry in the table of another card of the first series and associated therewith by the information in the entry to be updated.

Abstract: A connection oriented communications network 10 comprises a plurality of nodes including a plurality of edge nodes 12, 14, 16, 18. The network is arranged to define a primary tunnel connecting a primary one 12, 14 of the edge nodes to another edge node 14, 12 and a secondary tunnel connecting a secondary one 16, 18 of the edge nodes to another edge node 12, 14, 16, 18. The network is arranged to enable switching of traffic from the primary tunnel to the secondary tunnel in the event of detection of a failure in the primary tunnel.

Abstract: A protection scheme for a metro optical network involves programming ingress nodes and egress nodes with a primary multicast label switched path (LSP) and a back-up LSP to provide one-to-one protection. The primary and back-up LSPs are configured prior to the occurrence of a network fault to allow the network to transmit multicast communication when the fault occurs. Particularly, multicast communications are sent on the primary LSP during normal operation. However, when a network fault occurs, the nodes also send a duplicate multicast communication over the back-up LSP. Configuring the primary and back-up LSPs prior to the fault occurring avoids the need for signalling to establish a working LSP after a fault occurs.

Abstract: An apparatus and a method are described in which a flow of packets is distributed in several separate flows over several links (12) forming a logically aggregated link (11). The flow outgoing from each physical link is sent to its own policer (18) which applies to said flow a traffic policing algorithm with the policers being interconnected to exchange algorithm control parameter modification information to fit them in among the various policers while allowing for the control parameters of the others so that a distributed policer (15) is realized.

Abstract: A method and a transport scheme for packets of traffic over a logical link made up of the aggregation of several physical links (16) connecting a transmitting side to a receiving side in which flows of incoming packets are sent to a scheduler/shaper (12) which selects therefrom packets for creating a global flow of packets falling within the bandwidth offered by the logical link on the basis of the bandwidth capability offered by the logical link. A distributor (13) distributes the global flow over the plurality of physical links (16) making up the logical link, oversees the physical links and sends to the scheduler/shaper signalling of a bandwidth decrease caused by failures of one or more physical links. The scheduler/shaper (12) is arranged to allow automatically for the logical link bandwidth variations while selecting the packets from the various incoming queues depending on the associated service class so as to cause the global flow to fall within the aggregated logical link bandwidth.

Abstract: A method of providing data from a first network 100 to a second network wherein a first PEJ and a second PEK node are provided in the first network 100 and are each capable of supplying data to the second network, wherein: i. at any one time one of the first PEJ and second PEK nodes provides data to the second network; and ii. the first PEJ and second PEK nodes are arranged to communicate with one another such that the other of the nodes can provide data to the second network if a fault is detected, wherein the communications between the first and second node allow a fault to be detected.

Abstract: An apparatus for compensation or emulation of polarization mode dispersion (PMD) effects occurring in an optical signal traveling over an optical fiber based link comprises controllable birefringence sections and devices for polarization conversion. Each section comprises birefringence optical members or parts thereof, and each section is followed or preceded by one of the controllable devices for polarization conversion. The birefringence sections are at least three in number, and at least one of these has a propagation delay different from that of the other sections. The apparatus comprises a detection device for PMD output and control of the controllable devices for feedback adjustment.

Abstract: A method of detecting polarization mode dispersion (PMD) indicative parameters of an optical fiber link comprising at least one transmission channel in which is transmitted a first wideband optical signal with a bandwidth divided into sub-bands. For each sub-band is produced a second reference optical signal with which to find a third optical signal by superposition. For each of the third signals are calculated first parameters considered indicative of the PMD thereof, and with the first parameters of all the sub-bands are calculated second parameters considered indicative of the PMD of the first wideband signal. The method can be used as part of a PMD compensation method for a transmission system employing the parameters calculated for feedback piloting of a PMD compensator.

Abstract: A method of detecting polarization mode dispersion (PMD) indicative parameters of an optical fiber link comprising at least one transmission channel in which is transmitted a first wideband optical signal with a bandwidth divided into sub-bands. For each sub-band is produced a second reference optical signal with which to find a third optical signal by superposition. For each of the third signals are calculated first parameters considered indicative of the PMD thereof, and with the first parameters of all the sub-bands are calculated second parameters considered indicative of the PMD of the first wideband signal. The method can be used as part of a PMD compensation method for a transmission system employing the parameters calculated for feedback piloting of a PMD compensator.

Abstract: An apparatus (14) for compensation or emulation of PMD effects occurring in an optical signal travelling over an optical fiber based link comprises controllable birefringence sections (15-18) and devices (19-22) for polarization conversion. Each section comprises birefringence optical members or parts thereof and each section is followed or preceded by one of said controllable devices for polarization conversion. The birefringence sections (15-18) are at least three in number and at least one of these has a propagation delay different from that of the other sections.