Cut-through routing for network devices

摘要

Methods and systems for a network device. The network device includes a temporary memory storage device having a plurality of storage locations that are used to store packets received by a plurality of sub-ports. The network device includes a cut-through estimation circuit that estimates a cut-through threshold value based on which a certain portion of a packet has to be received and stored at one of the plurality of storage locations before the packet can be processed by one of the sub-ports that received the frame. The cut-through threshold value varies based on an operating speed of a network link the packet is received on, an operating speed of a network link the packet is transmitted on, and a protocol used for receiving and transmitting the packet.

主权项

1. A network device, comprising:
a plurality of base-ports, where each base-port is coupled to a plurality of network links and each base-port has a plurality of hardware based sub-ports configured to operate independently as a port for sending and receiving information using one of the plurality of network links at a plurality of rates complying with a plurality of protocols; wherein each sub-port is coupled to a network link from among the plurality of network links; a temporary memory storage device at each base-port having a plurality of storage locations that are used to store packets received by the plurality of sub-ports; wherein the memory storage device is shared among the plurality of sub-ports of a base-port such that each sub-port is provided access to one or more storage locations at a certain phase of a system clock cycle for the network device; a cut-through estimation circuit at each base-port that estimates a cut-through threshold value based on a certain portion of a packet that has to be received and stored at one of the plurality of storage locations before the packet is processed by one of the sub-ports that received the frame; wherein the cut-through threshold value is determined based on an operating speed of a receive network link the packet is received on, an operating speed of a transmit network link the packet is transmitted on, and a protocol used by a sub-port for receiving and transmitting the packet; wherein to determine the cut-through threshold value, the cut-through estimation circuit uses a first value and a second value to shift a maximum packet length for the packet, where the first value and the second value are obtained from a data structure and vary based on the operating speed of the network link the packet is received on and the operating speed of the network link the packet is transmitted on to its destination; and wherein the cut-through estimation circuit uses subtraction for estimating the cut-through value without using division when the operating speed of the receive network link the packet is received on and the operating speed of the transmit network link the packet is transmitted on are non-integer multiples.