Abstract: A method for actively detecting link failures on a high availability backplane architecture. The backplane system includes redundant node boards operatively communicating with redundant switch fabric boards. Uplink ports of the node boards are logically grouped into trunk ports at one end of the communication link with the switch fabric boards. A probe packet is sent, and a probing timer is set whenever either a specified number of bad packets are received, or an idle timer expires. If a response to the probe packet is received before the probe timer expires then the link is deemed valid, otherwise the link is presumed to have failed. Preferably, either the node boards or the switch fabric boards are configured to properly handle a probe pack, which preferably has identical source and destination addresses.

Abstract: A method of context switchover continuity is disclosed in which a context is sent from a transmitting entity to a receiving entity. Initial first and second context state entries are maintained in respective tables at the transmitting entity and at the receiving entity. The initial first and second context state entries include context state information about the context. New reconfigured first and second context state entries are created at the transmitting entity and the receiving entity having reconfigured context state information. The new reconfigured first and second context state entries are activated so as to enable the sending of a reconfigured context from a transmitting entity to a receiving entity. A plurality of contexts are included, and each of the plurality of contexts has respective initial first and second context entries in the respective tables.

Abstract: A task-based chip-level hardware architecture. The architecture includes a task manager for managing a task with task information, and a task module operatively connected to the task manager for performing the task in accordance with the task information.

Abstract: A method of forwarding messages among task blocks using a task manager. The task manager receiving the message at an input port. The method further comprises determining the destination of the message. The message is stored in a pre-allocated segment that is selected from a plurality of segments within an input buffer. Each pre-allocated segment is associated with an output buffer. The method further comprising moving the message to the output buffer associated with the pre-allocated segment by an arbitrator that uses a round robin scheme for polling each input port. The pre-allocated segment is selected based on the destination of the message. The message may further comprise a priority, wherein the message is routed to a switch plane based on the message control signals. The higher priority switch plane given priority whenever there is a resource conflict.

Abstract: A method and apparatus for processing packets carrying a voice payload are presented. The apparatus provides for the reduction of packet transport overheads by embedding a context switching header within pre-existing data transport protocol headers using spare bits as much as possible. The solution provides configurable support for multi-vendor equipment. Provisions are made for the hardware extraction of the context switching header from the packets as well as for the extraction of packets carrying a voice payload from a stream of packets carrying a mixed data traffic. The hardware extraction is supported using bit masks.

Abstract: A protocol and header format of a network architecture for communication between a plurality of network devices. In particular, the data frame is resolved at the source device to ascertain the data frame type, and the data frame is forwarded with a virtual network identifier and priority information from the source device to a destination device of the network. The forwarded data frame also includes control information.

Abstract: A system and method for implementing a control channel in a packet switched communications network. In a computer network, such as a local area network (LAN) it is known to utilize the Ethernet for distributing communications between stations. The Ethernet employs a standard frame format that includes header frames and, in particular a preamble frame which may be used to provide synchronization information between switching devices or nodes. The preamble frame is not required in a Gigabit Ethernet implementation and the present invention employs a portion of the preamble frame to implement a control channel between switching devices.

Abstract: A method of utilizing shared memory resources in switching Protocol Data Units (PDUs) at a data switching node is presented. The method includes reserving: a temporary memory storage portion for storing PDUs prior to queuing for processing thereof, a Class-of-Service memory storage portion to provide support Quality-of-Service guarantees, a shared memory-pool portion and an input port memory storage portion enabling non-blocking input port flow control. Provisions are made for PDU discard decisions to be delayed until after PDU headers are inspected subsequent to the receipt of each PDU. Provisions are made for well-behaved data flows conveyed via an input port to be protected against blocking from misbehaving data flows conveyed via other input ports of the data switching node.

Abstract: A method of scheduling queue servicing in a data packet switching environment is provided. The method includes a sequence of cyclical steps. The output queues are scheduled for servicing on a least credit value basis. An output queue is selected from a group of output queues associated with a communications port. The selected output port has at least one Payload Data Unit (PDU) pending transmission and a lowest credit value associated therewith. At least one PDU having a length is transmitted from the selected output queue and the credit value is incremented taking the length of the transmitted PDU into consideration. The transmission of PDUs is divided into transmission periods. Once per transmission period credit values associated with output queues holding PDUs pending transmission are decremented in accordance with transmission apportionments assigned for each output queue. The method emulates weighted fair queue servicing with minimal computation enabling hardware implementation thereof.

Abstract: A credit-based pacing scheme for heterogeneous speed frame forwarding. A control logic controls the transmission of data between a source device and a destination device in accordance with a handshaking protocol. Pacing logic paces the transmission of the data from the source device to the destination device to prevent congestion in the switching fabric. A credit scheme is used to arbitrate among multiple pacing modules per device, each forwarding data at a different rate.

Abstract: An end-to-end, closed loop flow and congestion control system for packet communications networks exchanges rate request and rate response messages between data senders and receivers to allow the sender to adjust the data rate to avoid congestion and to control the data flow. Requests and responses are piggy-backed on data packets and result in changes in the input data rate in a direction to optimize data throughput. GREEN, YELLOW and RED operating modes are defined to increase data input, reduce data input and reduce data input drastically, respectively. Incremental changes in data input are altered non-linearly to change more quickly when further away from the optimum operating point than when closer to the optimum operating point.