Abstract: The invention relates to data communications, more particularly to a protocol encapsulation technique which captures the time between frames at a transmitting site for comparison with an idle counter at a receiving site. At the originating site, the time between successive frames in the native protocol is encoded in an interframe time field associated with each respective frame, before the time encoded frame is mapped into the protocol associated with the transport medium. At the destination site, the framing associated with the transport medium is removed to reveal the interframe time field. The value contained in this field is compared with the value of an idle counter running at the native protocol rate. When the idle count is greater than or equal to the encoded inter-frame time, the data contained in the frame is then delivered to the client.

Abstract: This invention relates to a method and apparatus for controlling the flow of fiber channel (FC) data frames from a fiber channel link to a metropolitan area link of lesser bandwidth (a synchronous optical network (SONET)). The release of each data unit by a data source for transport onto the first channel is governed by a credit-based protocol whereby one data unit is released upon the provision of one credit unit. A first marker identifies a high limit H of the buffer at which a first condition occurs, H being less than N and the first condition applying when the number of data units in the buffer is greater than H. A second marker identifies a low limit L of the buffer at which a second condition occurs, L being less than H and the second condition applying when the number of data units in the buffer is less than L. A credit unit owed counter O counts the number of credit units which become owed to the data source when the second condition applies.

Abstract: A method and mapper apparatus for reallocating bandwidth used by a data tributary comprising data units, during transport of the data tributary over a communications link by a time division multiplexing (TDM) frame (e.g., a SONET frame comprising N×STS-1s) from a source device to a sink device. Each the data unit occupies one time slot of the frame and the data units are encoded to differentiate between payload data and control codes. At the source device, a designated code (IGNORE CODE) is inserted in each unallocated time slot to identify that the time slot contains no payload data (the designated code being ignored by the sink device). New set(s) of time slots to be allocated (i.e., to increase bandwidth) or de-allocated (i.e., to decrease bandwidth) to the tributary are determined. The new set(s) of time slots are communicated to the sink device. Confirmation of the communication is received from the sink device.

Abstract: Service path protection is provided for packet-based data services (e.g. GbE or FC) by making available to a protected service, as and when needed, preemptable (i.e. sharable) transport bandwidth (e.g. STS-1s for a SONET network) used, under normal conditions, to transport other data services. Each client-based service path is defined by a selectable working path when service protection has not been initiated for that service path and each working path comprises a selectable bandwidth, selectable portions of which are designated as unpreemptable and/or preemptable, whereby the preemptable bandwidth portions are made available for protection preemption by different service paths. A protection path is assigned to each protected service path, whereby each protection path comprises a selectable bandwidth having preemptable bandwidth portion(s) of working path(s) defining different service path(s) and/or unused network bandwidth.

Abstract: An apparatus and method for detecting and suppressing corrupted data frames transported from a SONET network to a receiver utilizing the SOF frame indicator to manage the buffer-to-buffer credit count. By verifying the integrity of the SOF frame indicator prior to forwarding it to the client receiver the apparatus and method ensure that the buffer-to-buffer credit count integrity is maintained while avoiding the introduction of latency. A frame de-encapsulation component produces data frames compatible with the receiver from SONET frames input thereto and outputs the receiver-compatible data frames. An idle frame signal generator generates idle frame signals. A Start of Frame (SOF) indicator detector detects a Start of Frame indicator in each data frame output from the frame de-encapsulation component, determines whether the Start of Frame indicator is valid or corrupted and produces an output signal indicative of that determination.

Abstract: A digital information mapper and method for mapping sequences of information characters into a SONET (synchronous optical network) payload in such a manner that there can be an arbitrary mixture of control and/or data values in those sequences. Each information character comprises 9 bits consisting of an 8 bit information byte, being either a control byte or a data byte, and one octet type bit identifying the byte as control or data. A processor applies a mapping algorithm of a mapping module to the input information characters. The mapping algorithm is applied to sequences of eight input information characters, the algorithm being operable to map the information bytes of each sequence of eight information characters to eight of a sequence of nine contiguous SPE octets. The algorithm then maps the octet type bits for the eight mapped information bytes of the character sequence to the ninth octet of the contiguous SPE octets of the SPE octet sequence.

Abstract: A method and system for in-service reallocation of bandwidth (i.e. STS-1's) in a synchronous optical network (SONET) i.e. without interruption of the transport of data frames transmitted from a transmit node and received at a receive node, the transmit node comprising a mapper/aggregator, a first bandwidth configuration memory associated with the mapper/aggregator and a transmit framer and the receive node comprising a demapper/deaggregator, a second bandwidth configuration memory associated with the demapper/deaggregator and a receive framer. First and second memory banks are provided to the first and second bandwidth configuration memory, whereby the first memory bank of the first bandwidth configuration memory comprises current bandwidth allocation mapping information used by the mapper/aggregator and the first memory bank of the second bandwidth configuration memory comprises current bandwidth allocation mapping information used by the demapper/deaggregator.