摘要:
Configuring a node (410) of a synchronization network involves identifying (10) possible alternative time synchronization trails arranged to carry time synchronization information for time synchronization at the node, and possible alternative frequency trails, arranged to carry frequency synchronization information for frequency synchronization at the node. Using information about the sources (20), a comparison of the trails (30) is biased to increase a likelihood of choosing time synchronization and frequency trails which share the same source, over a likelihood of choosing trails with different sources. This can help avoid divergence and consequent bit errors arising from phase errors, resulting from trails having different sources. It can encompass for example changing both to a new common source, or changing one or both trails while still using the old common source.
摘要:
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. At the second network element, the correction field of the ingress clock synchronization message is updated with the transit times to form an egress clock synchronization message.
摘要:
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 said network element. The ingress clock synchronization message includes a clock synchronisation message identifier and a correction field. The clock synchronisation message identifier is inserted into an optical channel frame overhead and the ingress clock synchronisation 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 synchronisation message identifier is determined across each of the network elements. At the second network element, the correction field of the ingress clock synchronisation message is updated with said transit times to form an egress clock synchronisation message.
摘要:
Configuring a node (410) of a synchronization network involves identifying (10) possible alternative time synchronization trails arranged to carry time synchronization information for time synchronization at the node, and possible alternative frequency trails, arranged to carry frequency synchronization information for frequency synchronization at the node. Using information about the sources (20), a comparison of the trails (30) is biased to increase a likelihood of choosing time synchronization and frequency trails which share the same source, over a likelihood of choosing trails with different sources. This can help avoid divergence and consequent bit errors arising from phase errors, resulting from trails having different sources. It can encompass for example changing both to a new common source, or changing one or both trails while still using the old common source.
摘要:
A method and system of distributing clock synchronization information within an optical communications network including a plurality of network elements, in which a first network element receives an ingress clock synchronization message, the ingress clock synchronization message including a clock synchronization message identifier and a correction field. The first network element inserts the clock synchronization message identifier into an optical channel frame overhead and inserts the ingress clock synchronization message into an optical channel frame payload. The first network element transmits the optical channel frame overhead and the optical channel frame payload to a second network element, and determines a transit time of the clock synchronization message identifier across each of the network elements. The second network element updates the correction field of the ingress clock synchronization message with said transit times to form an egress clock synchronization message.
摘要:
A node for a communications network has a converter for digitizing at a receiver clock rate a received optical signal received over an optical link from an optical transmitter at a source node, a framer for detecting frames and a forward error correction part for correcting errors in the payload of the frame. An error rate in the received payload part is monitored and a processor sends, according to the monitored error rate, a request to the optical transmitter to adapt a length of the transmitted forward error correction part and to adapt a clock rate of the transmission of the frame if FEC length is reduced or FEC is disabled. This can enable power saving, when less FEC information is being sent.
摘要:
A method for adapting the rates of a certain number of asynchronous HDLC channels (15) to a single clock domain suited for interfacing with an HDLC processor (13) through a synchronous pseudo-TDM interface (14) in which the HDLC channels are multiplexed in time and vice versa in the opposite direction. In one direction the algorithm is based on the writing of the HDLC channels in a dedicated buffer (17) and in reading these buffers with a common synchronous clock just above the expected maximum HDLC rate. The under-run condition is avoided by inserting neutral information between the end byte and the start byte of the HDLC packets when this is suggested by the buffer fill monitoring function. A simple function to locate the first and last bytes of each HDLC packet read by the buffer is hence used in combination with the buffer fill monitoring function. The algorithm is also suited in the opposite direction in which different asynchronous physical lines receive their HDLC channels from a synchronous TDM-type interface on condition that this interface clock domain be just below the minimum expected HDLC output rate. In this case also the under-run conditions are avoided by insertion of neutral data after having used the same algorithm described above. Adaptation devices and a telecommunications card using them are also proposed.
摘要:
The present invention consists of an information structure conceived for the transport of data in digital form from a transmitting element to a receiver. This structure calls for fields for transport of the data and heading information fields termed “overhead” which improve transmission reliability. This structure enables support of digital interconnections in an element of a transport network capable of switching various traffic types such as CBRx (for example STM-N e OC-N), VC-N, STS-N or ODUk. The structure also enables identification of the frame beginning, verification of the integrity and correctness of the switching, support of protection switching, and transport of quality and timing information associated with the switched entities.
摘要翻译:本发明包括以数字形式从发送元件传输到接收器的信息结构。 该结构要求用于传输数据的字段和提高传输可靠性的称为“开销”的标题信息字段。 该结构能够支持能够切换诸如CBRx(例如STM-N e OC-N),VC-N,STS-N或ODUk的各种业务类型的传输网络的元件中的数字互连。 该结构还能够识别帧的开始,完整性的验证和切换的正确性,保护切换的支持以及与切换的实体相关联的质量和定时信息的传输。
摘要:
An optical transport network signal (OTM) comprising at least one optical channel is received at a first network equipment. The optical transport network signal (OTM) is processed to extract optical data units (ODUk) for each optical channel (OCh). There is detection for defects during the processing. The optical data units are retransmitted within optical transport units (OTUk) towards a second network equipment. When a defect has been detected, the retransmitting comprises inserting an optical channel transport unit alarm indication signal (OTUk-AIS) in an optical channel transport unit (OTUk) containing optical channel data units (ODUk) that are affected by the detected defect. The second network equipment detects for the presence of the optical channel transport unit alarm indication signal (OTUk-AIS) and generation of an alarm is inhibited for any optical channel data units (ODUk) contained within the optical channel transport unit that comprises the optical channel transport unit alarm indication signal (OTUk-AIS). The network equipments can comprise a WDM or DWDM equipment and a cross-connect.
摘要:
Network node comprising input equipment, switching equipment and output equipment, the input equipment is arranged to be capable of packetizing time division multiplexed (TDM) traffic flows, the switching equipment is arranged to be capable of routing the packetized data from the input equipment to the output equipment, and the output equipment is arranged to be capable of reassembling the flows into time division multiplexed format, wherein the input equipment is also arranged to be capable of causing the data frequency of the packetized data sent to the switching equipment to be substantially equal to a predetermined data frequency.