Nortel Networks Corporation

Notel Networks Corporation

Christopher Thomas William Ramsden

David Michael Goodman

Christopher David Murton

John Paul Russell

James A Shields

David William Wiggins

James Alexander Shields

James Shields

A method of transmitting OSI layerdatacoms data by direct incorporation into a plurality of synchronous digital hierarchy virtual containers is disclosed, in which a higher bit rate OSI layerdata frame is multiplexed into a plurality of lower bit rate SDH (or SONET) virtual containers, which are transmitted simultaneously and in parallel over a synchronous communications network. The plurality of virtual containers are virtually concatenated by association of the payloads of the plurality of virtual containers. Re-assembly of the OSI layerdata frames from a plurality of virtually concatenated VCs is achieved by storing each received VC payload corresponding to an OSI layerdata frame in a corresponding respective memory location, and alternately reading interleaved bytes from the plurality of payloads under control of a plurality of read pointers.

Concatenation of containers in synchronous digital hierarchy network

A transmission apparatus and a method for operating the apparatus comprises means for controlling flow of frame based data transmitted from a local frame based data channel interface over a synchronous digital network. The method of operation comprises the transmitter receiving frame based data at a first rate whereafter a buffer is configured to receive the frame based data. A data amount threshold level for the buffer is pre-determined whereafter, with respect to the threshold level, an amount of transmitted frame based data that has been received is monitored. In response to monitoring the amount of data received, a signal, in the form of a pause frame, is generated wherein the signal is configurable to adapt the rate of transmission from the frame based data channel interface. Working in conjunction with the transmission means there is also provided a receiver for controlling flow of frame based data, received from a synchronous digital network, to a frame based data channel interface. The receiver is configured to receive the frame based data at a first rate whereafter a buffer is configured to receive the frame based data. Upon pre-determining a data amount threshold level for the buffer an amount of frame based data received is monitored with respect to the threshold level. In response to monitoring the amount of data received, a signal is generated in the form of a pause frame, wherein the pause frame signal is configurable to adapt the first transmission rate of the frame based data over the synchronous digital network to a second rate. In this way, the rate of transmission from a local Ethernet switch may be controlled and the rate of receipt of Ethernet based frame data from a synchronous digital network may be controlled. In the latter case pause frames may be incorporated into one or more synchronous digital hierarchy virtual containers.

Flow control of frame based data over a synchronous digital network

A frame based data communications network is interfaced to a synchronous digital hierarchy network via a plurality of frame based data port cards incorporated into a plurality of synchronous multiplexers. Each port card comprises a conventional frame based data port, a frame switch, a rate adapter means and a mapping means for mapping data frames into a plurality of SDH virtual containers. Frame based data is incorporated directly into a synchronous virtual container without encapsulation in an intermediate protocol. A number of topologies of a frame based data channel network are possible, overlaid on the underlying synchronous transport network, including an open loop topology, a ring mode topology, and a backhaul topology.

Frame based data transmission over synchronous digital hierarchy network

There is disclosed a method of converting synchronously between a plurality of VC-3 container streams and a plurality of STS-1 synchronous payload envelope streams within the synchronous digital hierarchy. A stream of VC-3 containers is converted to a stream of STS-1 SPEs by reading the VC-3s in a VC-4 container stream, adding redundant byte columns to each VC-3 stream and re-writing said VC-3 streams to an STS-3 synchronous payload envelope stream. Conversely, a plurality of STS-1 synchronous payload envelope streams are converted to a plurality of VC-3 virtual container streams by reading the STS-1 SPE streams from an STS-3C SPE stream; removing redundant stuff byte columns from each STS-1 SPE stream; writing the STS-1 SPE streams to a VC-4 virtual container stream; recalculating pointer positions, writing pointer bytes to the VC-4 stream, and adding a plurality of redundant stuff bytes to the VC-4 container stream.

Payload translation between frame options in synchronous digital hierarchy networks

In the situation that data switching is incorporated in a wide area telecommunications network it is advantageous to use a local area network protocol such as ethernet which allows network resources to be shared. However, this introduces a problem with respect to loops in the network and the possibility of infinite packet looping. If the known spanning tree algorithm is used to prevent infinite packet looping this is problematic because the known algorithm takes a relatively long time to take effect. An algorithm is described which is based on assumptions about the topology of the communications network and which is simpler and faster.

Growing community of inventors

Hertford, United Kingdom

Christopher Thomas William Ramsden