Abstract: In a system, the functionality is decentralized in a data transmission network so that the need of communications produced by and addressed to data terminals to pass by way of a single point in the data transmission network is diminished. A first data transmission installation is adapted to signal second data transmission installations, each of which is part of a ring-shaped data transmission topology, to be capable of building logical data transmission tunnels directed to the data terminals. Thereby, all the logical data transmission tunnels need not commence or, depending on the direction, terminate at the same point of a data transmission network. In addition, the data transmission installations present in a ring-shaped data transmission topology need not necessarily be taught routing information in order to enable each of these data transmission installations to send data transmission frames to be transmitted to another one of these data transmission installations.

Abstract: The invention relates to producing data traffic where the time intervals between successive data frames follow a predetermined probability distribution. In the present invention, it is surprisingly discovered that a time interval of a desired length between successive data frames can be produced by setting a certain bit quantity of digital stuffing data, defined on the basis of the target length of the time interval target, in a buffer memory (101), where successive data frames are waiting to be transmitted. The digital stuffing data is set in the buffer memory (101), so that the stuffing data is, in the read-out order, located between successive data frames.

Abstract: In a data communication system according to the invention the functionality of the gateway device is distributed in a data communication network thereby reducing the need to direct the data traffic from and to terminals (212, 213, 214) through a single point in the data communication network. A first data communication device (207) is arranged to make, through signalling, second data communication devices (204, 205, 206) capable of directing the data communications of the terminals to the starting points of the respective logical data communication tunnels (215, 216, 217). This way there is no need for all logical data communication tunnels to start from, or depending on the direction, to end at, the same point in the data communication network.

Abstract: The invention relates to determining a quantity to be measured from a communication system, such as a transmission delay or the phase difference of clock times. Measurement messages are transmitted (501, 502) between the two areas of the communication system in both transmission directions. Values of the time difference are calculated (503) for the measurement messages transmitted in at least one of the transmission directions, each of which values is the difference between the instant of reception measured at the reception and the instant of transmission measured at the transmission of the measurement message. The values of the time difference are used to calculate (504) an estimate of the distribution of the time difference, on the basis of which an estimate of the minimum value of the time difference is calculated (504).

Abstract: A method and apparatus for monitoring and limiting the transmission speed of a data traffic flow in a situation where the traffic flow also includes delay-critical traffic. With the sending of each protocol data unit it is determined whether the sending of the next protocol data unit should be delayed in order to meet a condition set on the transmission speed. It is also determined whether the transfer speed of delay-critical traffic meets a preset condition. If the transfer speed meets the condition, delay-critical protocol data units will not be delayed but if the condition is not met, delay-critical protocol data units will be delayed just like non-delay-critical protocol data units. Thus the transfer speed of non-delay-critical traffic adapts to variations in the transfer speed of delay-critical traffic and, furthermore, the transmission speed of the traffic flow can be monitored and limited.

Abstract: The invention relates to a method and equipment for controlling the congestion management and transmission-link-capacity scheduling in packet-switched telecommunications, in such a way that 1) it is possible to define what share of the capacity of the transmission link will be reserved for traffic representing a specific service level class, and 2) it is possible to define the weighting coefficient that the portion of the traffic exceeding the reservation of each service level class will use to compete for the portion of the capacity of the transmission link that is not reserved, or that is reserved but is not being used momentarily by traffic entitled to the reservation, and 3) it is possible to use overbooking, in such a way that the reduction in service quality due to overbooking affects only the service level class in which overbooking is used, and 4) it is possible to prevent an increase in delays detrimental to traffic-flow control even in a congestion situation arising from overbooking.

Abstract: The invention relates to transferring of a time of day value between network elements of a data transfer network. It has been surprisingly detected that the phase reference signals available to various network elements can be utilized in the synchronization of time of day values between these network elements. In the solution according to the invention, a first network element sends to a second network element a difference variable (401, 402, 403) that indicates how much the timing phase of the time of day value maintained in the first network element differs from the timing phase of the phase reference signal available to the first network element. In the second network element that receives the message, an estimate of the time of day value is formed (404, 405) based on the difference variable and the timing phase of the phase reference signal available to the second network element.

Abstract: A method and arrangement for adjusting the degree of filling of a jitter buffer in a network element receiving digital data. To the jitter buffer, there is connected a read-out unit for reading digital data from the jitter buffer. In the method, there is composed a time reserve indicator for the received protocol unit, the time reserve indicator being essentially the difference of an order indicator connected to the protocol unit and an order indicator connected to the operational cycle of the read-out unit. The time reserve indicator of the protocol unit indicates whether the protocol unit was received in good time, in order to ensure that the digital data is in the jitter buffer when the digital data is in turn to be read out. The degree of filling of a jitter buffer is adjusted on the basis of time reserve indicators composed for the received protocol units.

Abstract: The invention relates to a method and arrangement for transferring synchronizing information in a data transmission system including modem connections. The arrangement according to the invention comprises a modulator (207) that is arranged to generate an analog signal (222) modulated by synchronizing information, the frequency spectrum of said signal being located in a frequency range that falls outside the data transmission bands of the modem line connected to the network element. The arrangement includes a switching circuit (208) that is arranged to connect said analog signal to a data transmission cable (206) that forms part of said modem line connected to a network element. The arrangement includes a second switching circuit (209) that is arranged to receive said analog signal from a data transmission cable that forms part of the modem line connected to the second network element.

Abstract: The invention relates to transmitting digital information between the network elements of a frame switched data network. In the present invention, it has surprisingly been discovered that the padding bits of the data field of a minimum sized Ethernet frame can be used for transmitting digital information between the elements of a data network. In that case the frame data field (109) of a minimum sized Ethernet frame contains an information unit (DIU), the size of which in bytes is smaller than the minimum size of a frame data field, as well as other digital information (DI) that is written in an area (107) of the frame data field that corresponds to the padding bits. The invention makes it possible to also utilize the data transmission capacity needed for transmitting the padding bits.

Abstract: The invention relates to transmitting time information between elements of a data network. In the present invention, it has surprisingly been discovered that in a network transmitting packet, frame or cell switched data traffic, time stamp information can be transmitted from a network element (101) to another network element (102) by using that part (113a, 113c) of the bit stream (111b) to be transmitted which is connected, in the transmitting network element (101), to the transmitted bit stream in a location that is placed, in the flowing direction of the transmitted bit stream, after a transmission buffer (103) buffering data packets, frames or cells. In an arrangement according to the invention, the random-type share of the transmission delay experienced by the time stamp information is slight, because the time stamp information does not have to queue in the transmission buffer (103) buffering data packets, frames or cells.

Abstract: The invention relates to a method and an arrangement for regenerating a timing signal in digital data communication where two network elements operate in a master/slave loop timing mode. In a solution according to the invention two different frequency difference indicators are formed. Values or changes of the values of both of them in relation to time indicate a frequency difference between a reference timing signal present in a master device and a regenerated timing signal present in a slave device. One frequency difference indicator is formed on the basis of reception taking place in the master device, and the other one on the basis of reception taking place in the slave device. The frequency of the regenerated timing signal is adjusted utilizing information contained by both frequency difference indicators. The probability of incorrect frequency adjustment measures can be thereby reduced.

Abstract: The invention relates to a method and system for adjusting a clock signal placed in a network element of a data network. The clock signal is adjusted on the basis of difference values formed by means of received synchronizing messages. Each difference value is a difference of a reception time value and a transmission value of a received synchronizing message. The reception time value of the synchronizing message depends on a cumulated number of periods of the clock signal at a moment of arrival of the synchronizing message, and the transmission value depends on a position of the synchronizing message in a chronological transmission order of the synchronizing messages. In the adjusting process, an adjusting effect of the difference values belonging to a lower part (304) of a margin of fluctuation (306) of the difference values is weighted more heavily than an adjusting effect of the difference values belonging to an upper part (305) of the margin of fluctuation of the difference values.

Abstract: The invention relates to a method and an arrangement for transferring timing messages in a digital data transfer system. In a solution according to the invention a timing message is transferred (101, 102, 103) within control data carried in a protocol data unit. The timing message is dependent on a transmission moment of the protocol data unit from a network element of the digital data transfer system. The control data is either a synchronization status message (Ethernet-SSM) carried in an Ethernet-frame, an overhead (OH) of a Synchronous Optical Network-frame (SONET), or an overhead (OH) of a Synchronous Digital Hierarchy-frame (SDH). Therefore, the number of such protocol data units that are dedicated only for timing purposes can be reduced.

Abstract: The invention relates to producing data traffic where the time intervals between successive data frames follow a predetermined probability distribution. In the present invention, it is surprisingly discovered that a time interval of a desired length between successive data frames can be produced by setting a certain bit quantity of digital stuffing data, defined on the basis of the target length of the time interval target, in a buffer memory (101), where successive data frames are waiting to be transmitted. The digital stuffing data is set in the buffer memory (101), so that the stuffing data is, in the read-out order, located between successive data frames.

Abstract: The invention relates to a method and equipment for controlling the congestion management and transmission-link-capacity scheduling in packet-switched telecommunications, in such a way that 1) it is possible to define what share of the capacity of the transmission link will be reserved for traffic representing a specific service level class, and 2) it is possible to define the weighting coefficient that the portion of the traffic exceeding the reservation of each service level class will use to compete for the portion of the capacity of the transmission link that is not reserved, or that is reserved but is not being used momentarily by traffic entitled to the reservation, and 3) it is possible to use overbooking, in such a way that the reduction in service quality due to overbooking affects only the service level class in which overbooking is used, and 4) it is possible to prevent an increase in delays detrimental to traffic-flow control even in a congestion situation arising from overbooking.

Abstract: The invention relates to a method and equipment for performing flow shaping that maintains service quality in packet-switched telecommunications. Using the method according to the invention, the speed properties (CIR, PIR, CBS) of an aggregate flow (A) can be monitored and limited in a situation, in which the aggregate flow contains delay-critical traffic (V1), the forwarding of packets representing which cannot be delayed. The invention is based on the fact that, when forwarding packets representing the aggregate flow, a variable is updated, the value of which expresses the earliest permitted moment, at which a packet, representing traffic (V2) other than the delay-critical traffic, can be forwarded. In that case, the transfer speed of the traffic (V2) other than delay-critical traffic adapts to the variations in the transfer speed of the delay-critical traffic, allowing the speed properties of the aggregate flow to be monitored and limited.