Abstract: A node for use in a multi-source ring transmission system includes a controller and storage. Identifiers, such as ring addresses, for the relative first and relative last source nodes within the ring transmissions system are stored within the node's storage, in a squelch table for example. The node's relative first source node is the source node farthest upstream from the node and the node's relative last source node is the node that is farthest downstream from the node. The node blocks communications whenever both its relative first source node and its relative last source node fail.

Abstract: Methods and apparatus are disclosed for providing virtual rings in SONET networks. By using an unused byte in the SONET path overhead, in conjunction with multiframe operation, restoration is performed at the sub-network connection layer or path layer to provide a finer granularity of protection which provides more efficient use of bandwidth. By restoring the operation of the SONET path overhead before exiting a virtual ring created using the present invention, the present virtual ring can be applied to the existing SONET network. Since a virtual ring provides restoration at a path level, a virtual ring can be comprised of various SONET rate interfaces. Further, restoration circuits are not dedicated, but are shared to create virtual rings as needed, which increases bandwidth efficiency and which are automatically and quickly created without the need for a centralized controller.

Abstract: A restoration procedure for use in bidirectional multiplex section-switched ring transmission systems re-establishes a connection path by using a loopback connection at nodes bordering the failure and by then establishing a jumpered connection path, for each active tributary affected by the failure. The jumpered connection path at affected node eliminates any unnecessary loop formed in the re-established connection path caused by the loopback connection at the border nodes. There is stored in memory at each node (1) the provisioned connection path, (2) the jumpered path, and (3) a jumper flag is set indicating that a jumper connection exists. When the failure is cleared the (1) jumpered path is removed and its record erase from memory, (2) the provisioned connection path is restored, and (3) the jumper flag is reset. Advantageously, the this operation can be programmed into existing node controllers and is compatible with existing restoration procedures.

Abstract: A pair of SONET rings (12' and 14') can be interworked by providing at least two gateways (16.sub.m-1 and 16.sub.m) that are shared by each of the rings. Each shared gateway has the capability of transferring a block of optical information resident in a prescribed time slot in an interchange frame associated with one ring to a time slot in an interchange frame associated with the other ring so the block reaches its intended destination in that ring.

Abstract: Misconnections between communications circuits in a bidirectional line-switched ring transmission system are essentially eliminated by deterministically squelching in adjacent ring nodes, i.e., loop-back-switching nodes, communications circuits terminated in failed ring nodes in the ring transmission system. The deterministic squelching is realized by provisioning the ring nodes with all active communications circuits including those passing through the node which are terminated in other ring nodes in the bidirectional line-switched ring transmission system. Then, when one or more adjacent ring nodes fail, all active communications circuits terminated in those failed ring nodes are squelched in the adjacent ring nodes, i.e., in the loop-back-switching ring nodes.

Abstract: Communications circuit connectivity between a bidirectional line-switched ring transmission system and another ring transmission system is continued in the presence of the failure of a first shared node for communications circuits between the ring transmission systems by employing at least one additional shared node for the communications circuits; provisioning one or more duplex communications circuits between the first shared node and the additional shared node; and selectively allowing the one or more duplex communications circuits between the shared nodes to be established in the bidirectional line-switched ring when a ring node in the bidirectional line-switched ring in the first shared node has failed.

Abstract: Selective tributary switching is realized in a bidirectional transmission system by selectively switching, in accordance with the same rules governing the set-up and take down procedures of full line-switching, only that portion of the bandwidth of the particular line which has been provisioned to be line-switched. The remaining bandwidth can be left unprotected or, by for the first time combining line-switched ting functionality with path-switched ring functionality in the same ring transmission system, some remaining bandwidth can be path-switched. Furthermore, another degree of switching freedom is achieved in a four optical fiber bidirectional ring transmission system by selectively span-switching, but not ring-switching, specific bandwidth on the line. To this end, communications circuit provisioning information is provided in the ring nodes as to whether a particular communications circuit should be line-switched or not and, if not, whether it should be span-switched, path-switched or left unprotected.

Abstract: The possibility of passing off apparent "good" higher level digital signals that may include corrupted or failed lower level digital signals because of inter-ring grooming of the lower level digital signals from one path-switched ring to another path-switched ring employing at least a first shared node and a second shared node is minimized by dual feeding communications circuits from one path-switched ring to the other via the shared nodes and by provisioning at least one inter-ring groomed communications circuit from a secondary ring node of one of the shared nodes (secondary communications circuit) of a particular ring to be supplied to a primary ring node in the other shared node of the same ring.

Abstract: The possibility of passing off apparent "good" higher level digital signals that may include corrupted or failed lower level digital signals because of inter-ring grooming of the lower level digital signals from a bidirectional line-switched ring to a path-switched ring and vice versa which employ first and second shared nodes is minimized by dual feeding communications circuits from the bidirectional line-switched ring to the path-switched ring and vice versa via the shared nodes. An inter-ring groomed communications circuit is provisioned from a secondary ring node in the line-switched ring of one of the shared nodes (secondary communications circuit) to be supplied to a primary ring node in the other of the shared nodes of the line-switched ring. A replica of the secondary communications circuit is demultiplexed to obtain the lower level digital signals, which are evaluated on a pair-wise basis with corresponding lower level digital signals from the primary ring node.

Abstract: The possibility of passing off apparent "good" higher level digital signals that may include corrupted or failed lower level digital signals because of inter-ring grooming of the lower level digital signals from one bidirectional line-switched ring to another bidirectional line-switched ring, employing at least a first shared node and a second shared node, is minimized by dual feeding communications circuits from one line-switched ring to the other via the shared nodes. An inter-ring groomed communications circuit is provisioned from a secondary ring node of one of the shared nodes (secondary communications circuit) of a particular ring to be supplied to a primary ring node in the other shared node of the same ring. Additionally, a replica of the secondary communications circuit is demultiplexed in the primary ring node to obtain the lower level digitals signals therefrom.

Abstract: Communications circuit connectivity in a bidirectional line-switched ring transmission system is continued in the presence of the failure of a first ring node for communications circuits terminated in the ring node which are redirectable to an alternate (dual hubbing) ring node. The communications circuit are redirected by establishing a bidirectional communications circuit to the alternate ring node. In one example, redirection of the communications circuits is further realized by not squelching communications circuits terminated in the failed ring node in a ring node adjacent the failed ring node on one prescribed side which normally would have been squelched, while squelching communications circuits terminated in the failed ring node in a ring node adjacent to the other side of the failed ring node. This allows the redirectable communications circuits to be loop back switched so that they may be redirected to the alternate ring node.

Abstract: The spray mist is produced by ejecting the liquid from one or more nozzles (1) in the form of jets (2) disintegrating into drops and the liquid formed from the drops is then conveyed to a spray system (4) which is electrically insulated from the nozzles (1) and a powerful electric field is applied between the nozzles (1) and the spray system (4). A spherical impact electrode or a two-material spray nozzle insulated against earth under a high voltage may be used as spray system. The main advantage is that the smooth jet nozzle (1) and hence also the container for the liquid to be sprayed are at earth potential.