Abstract: An interface is disclosed that formats a first link (a source link--e.g., a T1 link) having N channels to fit into a second link (a source link--e.g., a PCM-30 or a doubled T1 link) having N+M channels. Each of the first and second links are implemented with primary rate carrier links, and have a standard payload portion and a standard overhead portion. A mechanism is disclosed for routing information between the first link and the second link, so that information being transported over the first link can also be transported over the second link. An adding mechanism is also disclosed for routing supplemental overhead information to at least one added overhead channel within the second link, wherein the added overhead channel occupies a standard payload portion of the second link. An overhead information bit is disclosed, which transmits information within a (k)th bit of an (l)th channel of each frame of the second link. An information bit signal is formed with at least five consecutive of the (k)th bits.

Abstract: A communications method and a network for carrying out the method are provided. The network includes a loopback command system and a first link station connected to a communications link. The link traverses several loopback-capable devices as it extends from the first link station to a second link station remote from the first link station. The loopback command system controls the loopback-capable devices to cause them to loopback. In order to command a loopback of a particular loopback-capable device, the first link station generates an initial loopback value and forwards the same over the link to a downstream loopback-capable device located along the link. Each loopback-capable device receives a loopback value from an upstream device, and compares if the received value is equal to a predetermined value. If the loopback value is equal to the predetermined value, the device is placed into a loopback state.

Abstract: A data transmission method and apparatus provides for transmitting lower data rate information in a higher data transmission rate environment. Information entities to be transmitted are broken into smaller entitles called nyblets. Higher data transmission rates are accomodated by accelerating a clock and clocking nyblets from memory at rate that allows the nyblets to be serially assembled into expected bit length words. Lower data rate information, which in conventional systems was transmitted redundantly to achieve compatibility with higher data rate systems, is now transmitted without duplication as a plurality of nyblets in series until the expected bit length is achieved. The result is that more information can be transmitted over a communication medium, since duplicate or redundant transmission of lower data rate information is avoided.

Abstract: Multi-layer printed circuit boards are sometimes connected to transmission paths which may be susceptible to electrical discharges associated with transient electrical events occurring along the transmission path. A method is provided for assuring that two respective layers of the printed circuit board are aligned within predetermined tolerances. Aligning respective layers within acceptable tolerances provides a means of assuring that predetermined distances between a ground layer and a power layer will be maintained, thereby ensuring that electrical arcing will not occur between the power and ground layer in the event of voltage spikes or current surges.