Abstract: A method and apparatus for a communications network that executes a medium access control (MAC) protocol that permits multiple access to a shared medium or shared switching fabric. The MAC protocol uses a BANDWIDTH_ALLOCATOR to regulate access to the network by sending a permission message to a NODE, allowing it to transmit to a specific set of NODEs for a specific length of time. The medium and switching fabric can carry one or more protocols, each of varying framing format and native bitrate. The switching fabric provides a connection-oriented bufferless data transport service that preserves frame ordering. An illustrative embodiment uses a slotted master/slave time-division multiplexed access (TDMA) scheme to allow flexible provisioning of network bandwidth.

Abstract: The present invention describes a system for providing quality of service (QoS) features in communications switching devices and routers. The QoS provided by this system need not be intrinsic to the communication protocols being transported through the network. Preferred embodiments also generate statistics with the granularity of the QoS. The system can be implemented in a single application-specific integrated circuit (ASIC), in a chassis-based switch or router, or in a more general distributed architecture. The system architecture is a virtual output queued (VOQed) crossbar. The administrator establishes policies for port pairs within the switch, and optionally with finer granularity. Frames are directed to unique VOQs based on both policy and protocol criteria. Policies are implemented by means of a scheduling engine that allocates time slices (minimum units of crossbar access).

Abstract: A data switchover from a first switching module to a second switching module has no data loss. A graceful code upgrade in a Fibre Channel network, for example, with no data loss can be achieved.