Abstract: A system and method for late-dropping packets in a network switch. A network switch may include multiple input ports, multiple output ports, and a shared random access memory coupled to the input ports and output ports by data transport logic. Packets entering the switch may be subject to input thresholding, and may be assigned to a flow within a group. A portion of a packet subject to input thresholding may be accepted into the switch and assigned to a group and flow even if, at the time of arrival of the portion, there are not enough resources available to receive the remainder of the packet. This partial receipt of the packet is allowed because of the possibility of additional resources becoming available between the time of receipt of and resource allocation for the portion of the packet and receipt of subsequent portions of the packet.

Abstract: A system and method providing virtual channels with credit-based flow control on links between network switches. A network switch may include multiple input ports, multiple output ports, and a shared random access memory coupled to the input ports and output ports by data transport logic. Two network switches may go through a login procedure to determine if virtual channels may be established on a link. A credit initialization procedure may be performed to establish the number of credits available to the virtual channels. Credit-based packet flow may then begin on the link. A credit synchronization procedure may be performed to prevent the loss of credits due to errors. On detecting certain error conditions, a virtual channel may be deactivated. In one embodiment, the link is a Gigabit Ethernet link, and the packets are Gigabit Ethernet packets. The packets may encapsulate storage format (e.g. Fiber Channel) frames.

Abstract: A system and method for enabling a network switch to transmit queued packets to a device when opened by the device, and thus to utilize the Fibre Channel Arbitrated Loop (FC-AL) in full-duplex mode when possible. The switch may include a plurality of queues each associated with a device on the FC-AL for queuing incoming packets for the device. The switch may determine a next non-empty queue, open the device associated with the queue, and send packets to the device. The device may send packets to the switch concurrently with receiving packets from the switch, thus utilizing the FC-AL in full-duplex mode. When a device opens the switch to transmit packets to the switch, the switch may determine if there are packets for the device in the queue and, if so, send packets to the device concurrently with receiving packets from the device, thus utilizing the FC-AL in full-duplex mode.