Abstract: A method of operation of a Multiprotocol Label Switching network involves, in an active node of the network, receiving a first data packet from a source node and forwarding the first data packet to a destination node. At the same time, the active node measures a residence time of the first data packet in the active node. The active node then sends a further data packet containing residence time information.

Abstract: A method for detecting a timing reference affected by a change in path delay asymmetry in a communications network comprising a master node having a master clock and a plurality of slave nodes each having a respective slave clock is provided. The method comprises: determining that a first timing reference received by a first slave node indicates a time correction to its slave clock greater than a time correction threshold; determining whether one or more other slave nodes have received a timing reference indicating a time correction to their slave clock greater than a time correction threshold; and determining whether the first timing reference is affected by a change in path delay asymmetry based on the determining of whether one or more other slave nodes have received a timing reference indicating a time correction to their slave clock greater than a time correction threshold.

Abstract: A method performed by a network element that transfers first and second packet flows of the same traffic handling class comprises the step of receiving, from a network controller, information defining a relative forwarding order between first and second packet flow packets. Upon receipt, at least one ingress port of the network element, of a first and a second packet, determining that the first packet belongs to the first packet flow and the second packet to the second packet flow. The first and second packets will then be forwarded towards at least one egress port of the network element in an order defined by the information received from the network controller.

Abstract: A method (100, 200) in a synchronisation control unit is disclosed. The method enables synchronisation of a plurality of distributed devices with a network and comprises the steps of receiving a wireless synchronisation signal from a network node over a wireless channel (104, 204) and processing the received synchronisation signal (108, 208). The method further comprises transmitting the processed synchronisation signal to the plurality of distributed devices over a local connection which is different to the wireless channel over which the wireless synchronisation channel is received (120, 220). Also disclosed are a synchronisation control unit (300, 400) and a computer program product.

Abstract: Configuring a node (410, A-I, L-O) of a synchronization network, involves determining information about synchronization sources of a plurality of synchronization trails for passing synchronization information from the synchronization source (A, L, O, PRC) to the node to provide a synchronization reference. After determining automatically (210, 230, 330, 335, 340) synchonization transmission characteristics of trails (EF, FG, GH, HM, MN, OF, FI, IH) which use packet-based communication, the trails are compared automatically (240, 370), using their source information and their synchronization transmission characteristics, for selecting which of these trails to use for providing the synchronization reference for the node (N).

Abstract: A method for measuring asymmetry in propagation delay of first and second links which connect a first node to a second node of a communication network. The method comprises measuring (101) a round trip delay of the first link. The round trip delay can be measured by transmitting (102) a test signal from the first node to the second node over the first link and receiving a reply to the test signal from the second node over the first link. The method further comprises measuring (105) a round trip delay of the second link. The round trip delay can be measured by transmitting (106) a test signal to the second node over the second link and receiving a reply to the test signal from the second node over the second link. A difference in the propagation delay of the first link with respect to the second link is determined (109) using the measured round trip delays of the first link and the second link.

Abstract: A User Equipment comprises a master clock, for example a Precision Time Protocol, PTP, or Precision Time Control Protocol, PTCP, network clock. The User Equipment further comprises circuitry configured to set the master clock based on signals from a wireless communications network node and a time offset, wherein the time offset is based on the propagation delay between the wireless network node and the User Equipment. The circuitry is further configured to send timing information to a network device in a communications network having a slave clock, whereby the network device can synchronize its slave clock with respect to the master clock comprised within the User Equipment.

Abstract: A method distributes clock synchronization information within an optical communications network comprising a plurality of network elements. The method receives an ingress clock synchronization message at a first said network element. The ingress clock synchronization message includes a clock synchronization message identifier and a correction field. The clock synchronization message identifier is inserted into an optical channel frame overhead and the ingress clock synchronization message is inserted into an optical channel frame payload. The optical channel frame overhead and the optical channel frame payload are transmitted across the first network element, across the network to a second said network element, and across the second network element. A transit time of the clock synchronization message identifier is determined across each of the network elements.

Abstract: A method and apparatus for determining propagation delay of a first path and or of a second path which connect a first transceiver unit associated with a first clock to a second transceiver unit associated with a second clock in a communications network. The apparatus comprises a control unit configured to cause the first transceiver unit to transmit a first signal to the second transceiver unit over the first path and to receive a reply to the first signal from the second transceiver unit over the second path, and to transmit a second signal to the second transceiver unit over the second path and to receive a reply to the second signal from the second transceiver unit over the first path.

Abstract: A method of providing a path delay asymmetry for time synchronization between a master clock at a first client node and a slave clock at a second client node. The method comprises: mapping a first time protocol signal (TPS) carrying master clock time protocol data (TPD) onto a first signal; determining a forward mapping delay (dmf); mapping a second TPS carrying slave clock TPD onto a second signal; determining a reverse mapping delay (dmr); applying FEC to the first signal, determining a forward FEC delay (dfecf); applying FEC to the second signal; determining a reverse FEC delay (dfecr); providing dmf, dmr, dfecf and dfecr to a calculation element; calculating a path delay asymmetry in dependence on dmf, dmr, dfecf and dfecr; and providing it to a time protocol client at the second client node.

Abstract: A synchronization module is associated with a network node of a communication network which includes at least one Synchronization Master entity. The synchronization module has knowledge of a plurality of Synchronization Master references. Endpoints of paths of the plurality of Synchronization Master references are obtained. Each of the paths extends between one Synchronization Master entity and the first or the second access network node. The paths are obtained from a synchronization report module based on the obtained endpoints. For each of the Synchronization Master references, a first path and a second path of the obtained paths are selected. A time synchronization inaccuracy value between the first and the second access network node is calculated based on the selected paths. A Synchronization Master reference is selected based on the calculated time synchronization inaccuracy values, and the first and the second access network nodes are notified which Synchronization Master reference was selected.

Abstract: A backhaul domain of the communication network is determined 400, and a request for a synchronisation reference is received 402 from the first access node, the request comprising, ID:s of the first and second access nodes. For each one of the first and second access nodes, a first and a second combination are determined 404 of a first and a second respective synchronisation reference and related synchronisation paths extending between synchronisation reference nodes of the synchronisation references and the access nodes. For each one of the first and second access nodes, the first or the second combination of synchronisation reference and related synchronisation path is selected 406 based on synchronisation requirements for the first and second access nodes, and the first path or the second path is requested to be set-up 408 according to the selected 406 combination.

Abstract: Configuring a node (410, A-I, L-O) of a synchronization network, involves determining information about synchronization sources of a plurality of synchronization trails for passing synchronization information from the synchronization source (A, L, O, PRC) to the node to provide a synchronization reference. After determining automatically (210, 230, 330, 335, 340) synchronization transmission characteristics of trails (EF, FG, GH, HM, MN, OF, FI, IH) which use packet-based communication, the trails are compared automatically (240, 370), using their source information and their synchronization transmission characteristics, for selecting which of these trails to use for providing the synchronization reference for the node (N).

Abstract: A method distributes clock synchronization information within an optical communications network having a plurality of network elements. The method receives an ingress clock synchronization message at a first network element. The ingress clock synchronization message includes a clock synchronization message identifier and a correction field. The clock synchronization message identifier is inserted into an optical channel frame overhead and the ingress clock synchronization message is inserted into an optical channel frame payload. The optical channel frame overhead and the optical channel frame payload are transmitted across the first network element, across the network to a second network element, and across the second network element. A transit time of the clock synchronization message identifier is determined across each of the network elements.

Abstract: Systems and methods of transporting internal radio base station (RBS) interface information over a packet network are presented. In one exemplary embodiment, in an interworking function (IWF) for communicating packets between a radio equipment (RE) and a radio equipment controller (REC) of a radio base station (RBS), a method may include receiving a packet sent from another IWF and having internal RBS interface information and residence time measurement (RTM) information that characterizes an asymmetry between processing times on links in different directions between the RE and the REC. Further, the method may include determining an asymmetry compensation that compensates for the asymmetry using the RTM information. Also, the method may include applying the asymmetry compensation to a timestamp of the internal RBS interface information to obtain an updated internal RBS interface information.

Abstract: A method of determining properties of an optical communications path between a first optical network node (A) and a second optical network node (B) determines, at the second optical network node (B), a time difference between respective first and second optical test signals received on different wavelengths (?1, ?2) from the first optical network node. The method also determines, at the second optical network node (B), a real-time chromatic dispersion parameter for each of the wavelengths using a respective coherent receiver at the second optical network node. The method can be used to determine length of the path between the nodes (A, B). The method can be used to determine propagation delay between the nodes (A, B), or asymmetry in propagation delay between the nodes (A, B). Where separate paths are used for forward and reverse transmission directions, measurements can be made of each path.

Abstract: Method and arrangement for providing delay information to synchronisation packets passing a transport network node. In a transport network node synchronisation packets propagate from a synchronisation master node towards boundary clock nodes. The synchronisation packets pass the transport network node, in which the synchronisation packets are received, and a level of delay is determined. Furthermore, when the level of delay for the synchronisation packets is above a threshold, the synchronisation packets are marked with a delay indication. The received synchronisation packets are sent to the boundary clock node or ordinary clock node, whether or not they are marked. By implementing functionality for determining a level of delay of synchronisation packets, and marking passing synchronisation packets with delay indications, boundary clock nodes and ordinary clock nodes may differentiate the received synchronisation packets based on the delay identifications.

Abstract: Systems and methods of transporting internal radio base station (RBS) interface information over a packet network are presented. In one exemplary embodiment, in an interworking function (IWF) for communicating packets between a radio equipment (RE) and a radio equipment controller (REC) of a radio base station (RBS), a method may include receiving a packet sent from another IWF and having internal RBS interface information and residence time measurement (RTM) information that characterizes an asymmetry between processing times on links in different directions between the RE and the REC. Further, the method may include determining an asymmetry compensation that compensates for the asymmetry using the RTM information. Also, the method may include applying the asymmetry compensation to a timestamp of the internal RBS interface information to obtain an updated internal RBS interface information.

Abstract: A method for detecting a timing reference affected by a change in path delay asymmetry in a communications network comprising a master node having a master clock and a plurality of slave nodes each having a respective slave clock is provided. The method comprises: determining that a first timing reference received by a first slave node indicates a time correction to its slave clock greater than a time correction threshold; determining whether one or more other slave nodes have received a timing reference indicating a time correction to their slave clock greater than a time correction threshold; and determining whether the first timing reference is affected by a change in path delay asymmetry based on the determining of whether one or more other slave nodes have received a timing reference indicating a time correction to their slave clock greater than a time correction threshold.

Abstract: A synchronisation module is associated with a network node of a communication network which includes at least one Synchronisation Master entity. The synchronisation module has knowledge of a plurality of Synchronisation Master references. Endpoints of paths of the plurality of Synchronisation Master references are obtained. Each of the paths extends between one Synchronisation Master entity and the first or the second access network node. The paths are obtained from a synchronisation report module based on the obtained endpoints. For each of the Synchronisation Master references, a first path and a second path of the obtained paths are selected. A time synchronisation inaccuracy value between the first and the second access network node is calculated based on the selected paths. A Synchronisation Master reference is selected based on the calculated time synchronisation inaccuracy values, and the first and the second access network nodes are notified which Synchronisation Master reference was selected.