Abstract: Delivering multicast data traffic over a communication network includes a first network node delivering multicast data traffic to second network nodes. The first and second network nodes are connected by a transmission network in a ring architecture and implement a point-to-multipoint layer 2 protocol. A method includes at the first network node: collecting alarms signals indicative of a failure along the whole ring and of the second network nodes. Based on a current state of the alarm signals, delivering the multicast data traffic either in a first delivery direction along the ring, or in a second delivery direction along the ring opposite to the first delivery direction, or in both the first and second delivery directions. At each of the second network nodes: collecting alarm signals indicative of a failure of the transmission network locally to the second network node and of the second network node.

Abstract: Delivering multicast data traffic over a communication network includes a first network node delivering multicast data traffic to second network nodes. The first and second network nodes are connected by a transmission network in a ring architecture and implement a point-to-multipoint layer 2 protocol. A method includes at the first network node: collecting alarms signals indicative of a failure along the whole ring and of the second network nodes. Based on a current state of the alarm signals, delivering the multicast data traffic either in a first delivery direction along the ring, or in a second delivery direction along the ring opposite to the first delivery direction, or in both the first and second delivery directions. At each of the second network nodes: collecting alarm signals indicative of a failure of the transmission network locally to the second network node and of the second network node.

Abstract: Extra traffic paths are provided in a communication network including at least two protection channels associated to respective transmission channels. Each protection channel admits an active state for carrying, in the presence of a failure in the associated transmission channel, traffic to be carried by the associated transmission channel, and a stand-by state, wherein the protection channel is adapted to carry extra traffic. The protection channels are run in a sub-network connection protection scheme, whereby one of the protection channels in its stand-by state is adapted to ensure recovery of extra traffic carried by the other protection channel while the other protection channel is switched to its active state or is subject to failure.

Abstract: A method of designing a transport network having a plurality of network elements and a plurality of connections between the network elements by (a) defining a first network configuration and at least one alternative network configuration for the same transport network; (b) calculating for each network configuration, a probability function representing, for each maximum number of routable flows, the probability of routing such a number of flows in the network configuration currently considered; (c) calculating for each network configuration, a unit-cost-per-flow function calculated as the ratio between a sum of the costs relative to the network elements of the network configuration currently considered and the probability function; and (d) comparing the unit-cost-per-flow functions of the network configurations considered, for choosing a network configuration having a lowest unit-cost-per-flow value.

Abstract: In order to measure the amplitude of a periodic signal of known frequency which may be heavily contaminated by noise and whose phase is not known at the point of measurement, e.g. at an output end of an optical fiber, two samples are periodically taken in every cycle at instants spaced apart by a quarter-cycle. The two samples are accumulated over N cycles and the signs of the resulting algebraic sums are compared at every N.sup.th cycle to determine whether the sampling phases should be advanced or retarded within a cycle by a predetermined increment .DELTA. in order to let the first and the second sample of a pair respectively approach the peak and the zero crossing of a half-cycle of the signal wave at which point, with the noise more or less balanced out, the second sum is substantially zero while the first sum represents N times the actual signal amplitude.