Abstract: A FIFO memory receives data transfer requests before data is stored in the FIFO memory. Multiple concurrent data transfers, delivered to the FIFO memory as interleaved multiple concurrent transactions, can be accommodated by the FIFO memory (i.e., multiplexing between different sources that transmit in distributed bursts). The transfer length requirements associated with the ongoing data transfers are tracked, along with the total available space in the FIFO memory. A programmable buffer zone also can be included in the FIFO memory for additional overflow protection and/or to enable dynamic sizing of FIFO depth.

Abstract: A loop network hub port with an automatic bypass feature. The automatic bypass feature causes the hub port to enter a bypass mode upon detection of a specified loop failure initialization sequence from a node port attached to the hub port. The hub port does not propagate loop failure initialization data generated by the attached node port upon the failure of a data channel from the hub port to the node port. The hub port replaces loop failure initialization data received from the node port with buffer data and conceals the node port failure from the remainder of the loop. Upon detection of the loop failure initialization sequence received from the attached node port, the hub port enters a bypass mode and maintains that bypass mode until a recovery sequence is received from the node port. At that point, the hub port reinserts the node port into the loop.

Abstract: A system and method of sanitizing a data frame from a node in a network loop includes receiving the data frame from the node, and, when the data frame includes invalid data, replacing a first word of the invalid data with a frame termination primitive and subsequent words of the invalid data with buffer data.

Abstract: A frame receive queue may perform disassembly and validation operations on frames received by a node in a Fiber Channel network. The frame receive queue may store information used for later processing of the frames, e.g., header data and the first eight payload words, in an on-chip memory for fast processor access. The payload data for the frames may be stored in a larger, external memory.

Abstract: A loop network hub including a hub port with a loop initialization insertion mechanism. The loop initialization insertion mechanism causes a hub port which detects a new node port connection to automatically begin generating loop initialization data. A hub port continues to generate loop initialization data until that hub port receives a loop initialization sequence. The loop initialization data propagates around the loop of the hub, halting ordinary processing. In this way, the entire loop is cleared. Upon receiving a loop initialization sequence, the hub port originating the loop initialization data inserts the new node port into the loop. At this point, loop initialization begins and each node port in the loop network obtains a unique loop network address.

Abstract: A system and method of sanitizing a data frame from a node in a network loop includes receiving the data frame from the node, and, when the data frame includes invalid data, replacing a first word of the invalid data with a frame termination primitive and subsequent words of the invalid data with buffer data.

Abstract: A system and method of sanitizing a data frame from a node in a network loop includes receiving the data frame from the node, and, when the data frame includes invalid data, replacing a first word of the invalid data with a frame termination primitive and subsequent words of the invalid data with buffer data.

Abstract: A FIFO memory receives data transfer requests before data is stored in the FIFO memory. Multiple concurrent data transfers, delivered to the FIFO memory as interleaved multiple concurrent transactions, can be accommodated by the FIFO memory (i.e., multiplexing between different sources that transmit in distributed bursts). The transfer length requirements associated with the ongoing data transfers are tracked, along with the total available space in the FIFO memory. A programmable buffer zone also can be included in the FIFO memory for additional overflow protection and/or to enable dynamic sizing of FIFO depth.

Abstract: A loop network hub port with an automatic bypass feature. The automatic bypass feature causes the hub port to enter a bypass mode upon detection of a specified loop failure initialization sequence from a node port attached to the hub port. The hub port does not propagate loop failure initialization data generated by the attached node port upon the failure of a data channel from the hub port to the node port. The hub port replaces loop failure initialization data received from the node port with buffer data and conceals the node port failure from the remainder of the loop. Upon detection of the loop failure initialization sequence received from the attached node port, the hub port enters a bypass mode and maintains that bypass mode until a recovery sequence is received from the node port. At that point, the hub port reinserts the node port into the loop.

Abstract: A loop network hub port with an automatic bypass feature. The automatic bypass feature causes the hub port to enter a bypass mode upon detection of a specified loop failure initialization sequence from a node port attached to the hub port. The hub port does not propagate loop failure initialization data generated by the attached node port upon the failure of a data channel from the hub port to the node port. The hub port replaces loop failure initialization data received from the node port with buffer data and conceals the node port failure from the remainder of the loop. Upon detection of the loop failure initialization sequence received from the attached node port, the hub port enters a bypass mode and maintains that bypass mode until a recovery sequence is received from the node port. At that point, the hub port reinserts the node port into the loop.

Abstract: A scalable hub divided into a plurality of internal hubs. Each internal hub is connected to a subsequent internal hub in a loop topology. The connection point for each internal hub to the interhub loop is a port which either bypasses that internal hub, isolating the disconnected internal hub, or connects that internal hub to the interhub loop, such that data flows between that internal hub and the interhub loop. In addition the preferred embodiment provides graceful degradation when an internal hub connected to the interhub loop fails.

Abstract: Methods and apparatus for implementing a technique for sanitizing data frames in a network loop.

Abstract: A hub port in a hub of a loop network which detects and replaces invalid data and invalid control signals in the datastream of the loop. The hub port detects invalid data and invalid control signals or primitives received from an attached node port and substitutes buffer data or valid primitives. The hub port substitutes buffer data or primitives which have correct running disparity for the datastream at the point of substitution. In another implementation, an error detection device is included in a loop network and monitors the datastream of the loop network. The error detection device detects invalid data and invalid control signals or primitives received from an upstream node in the loop and substitutes buffer data or valid primitives. The error detection device substitutes buffer data or primitives which have correct running disparity for the datastream at the point of substitution.

Abstract: A port for connecting a node to a network loop is disclosed. The port includes a detect element, a frame termination generator, a buffer data generator, a switching element, and a control element. The detect element monitors data from the node and sets an error flag when invalid data is received at the port. The frame termination generator generates frame termination primitives. The buffer data generator generates buffer data. The switching element has a control input, an output, and a plurality of data inputs. Each of an output of the node, the upstream node, the frame termination generator, and the buffer data generator is connected to a corresponding data input. The control element is connected to the detect element and the control input of the switching element. The control element selects, according to the error flag, one of the data inputs of the switching element. The selection connects to the output of the switching element to be output by the port to a downstream node.

Abstract: Methods and apparatus for implementing a technique for inserting and removing a node in a network loop. In a preferred implementation, a hub port includes a detect element which monitors data from the node and from an upstream node. The detect element sets a first flag when a primitive is received at the port, and sets a second flag when a primitive which is a frame termination primitive is received at the port. A frame termination generator generates frame termination primitives and a buffer data generator generates buffer data. A switching element has a control input, an output, and a plurality of data inputs. One data input is connected to each of an output of the node, the upstream node, the frame termination generator, and the buffer data generator. A control element is connected to the detect element and the control input of the switching element.

Abstract: A loop network hub port with an automatic bypass feature. The automatic bypass feature causes the hub port to enter a bypass mode upon detection of a specified loop failure initialization sequence from a node port attached to the hub port. The hub port does not propagate loop failure initialization data generated by the attached node port upon the failure of a data channel from the hub port to the node port. The hub port replaces loop failure initialization data received from the node port with buffer data and conceals the node port failure from the remainder of the loop. Upon detection of the loop failure initialization sequence received from the attached node port, the hub port enters a bypass mode and maintains that bypass mode until a recovery sequence is received from the node port. At that point, the hub port reinserts the node port into the loop.

Abstract: In a loop network system, a method and apparatus for automatic bypass of a node port associated with a hub port when the node port generates a number of errors beyond a threshold level. In one aspect, a programmable error control circuit provides this automatic bypass. The tolerance level is set through programmable parameters including a number of errors as well as a time interval to evaluate the number of errors detected. After a node port has been bypassed by the error control circuit, the error control circuit continues to monitor the error generation of the node port. When that error generation has reached an acceptable tolerance level, the error control circuit automatically reinserts the node port into the loop. The error control circuit provides statistical reporting on the number of errors as well as the number of bypasses generated at a particular hub port.

Abstract: Methods and apparatus for implementing a technique for determining a data rate of a serial bitstream using pattern recognition and for matching a clock speed of a deserializer to that data rate. In one implementation, a port for connecting a network device to a network includes a data input for receiving a bitstream from a network, where the bitstream has a data rate; a deserializer connected to the data input, where the deserializer deserializes the bitstream received via the data input, generating data characters; and a network device connected to the deserializer, where the network device receives data characters from the deserializer and determines the data rate of the bitstream by recognizing patterns in the data characters generated by the deserializer. In another implementation, a node port also sets a clock speed of the deserializer to match the data rate of the bitstream.

Abstract: A hub port which maintains a constant phase in a datastream and reduces jitter transfer to an attached node port. The hub port includes circuitry for maintaining constant bit boundaries for all data transmitted along the hub loop from that hub port using an internal clock. In addition, the internal clock is used to reduce jitter transfer.

Abstract: A method and apparatus for processing and transferring frames of data in a computer data link that maps incoming frames to a specific buffer ring in host memory based on routing control and type fields in each frame. More particularly, a Fibre Channel link port contains receiver routing code (RRCode) registers that allow host software to set up routing control (R.sub.-- CTL) match and mask fields, and TYPE match and mask fields. The link port uses these registers to match and mask against corresponding R.sub.-- CTL/TYPE fields in a received frame to determine which of several R.sub.-- CTL/TYPE host memory buffer rings should be used to store the received frame. The link port places a code (RRCode) in a start of frame (SOF) status word associated with a frame. The RRCode indicates a specific R.sub.-- CTL/TYPE host memory buffer ring, or indicates that no match was found or that multiple matches were found.