US 2002/0118640 A1 · Dynamic selection of lowest latency path in a network switch

Abstract

A system and method for low latency switching of data 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. Under normal operation, the data transport logic stores packet data into the memory. Later, the packet data is read from the memory and output to a destination output port. To reduce latency when the switch is not congested, the switching logic may be configured to perform a cut-through operation by routing packets directly from input ports to output ports without storing any portion of the packet in the memory. Alternatively, the switch may begin forwarding the stored packet data to the output port before the entire packet has been received or stored in the memory.

Claims54

Dependent claims

A method for switching packets in a network switch, the method comprising:

receiving data forming a packet, wherein the packet is to be routed to at least one destination output port of a plurality of output ports that are part of the network switch;
determining whether the destination output port has sufficient resources available to handle the data without causing an overflow;
routing the data to the destination output port if sufficient resources are available;
and
if sufficient resources are not available:
storing the data to a random access memory;
waiting until the destination output port has sufficient resources available;
and
transferring the data from the random access memory to the destination output port.

6 more elements

A network switch comprising:

a plurality of input ports configured to receive data forming one or more packets;
a plurality of output ports configured to convey the packets out of the switch;
a random access memory;
and
data transport logic coupled between the input ports, the output ports, and the memory,
wherein a first input port is configured to request cut-through routing from at least one destination output port in response to receiving data corresponding to a first packet that is a candidate for cut-through routing,
wherein the desltination output port is configured to convey a signal granting cut-through to the first input port if the destination output port has sufficient resources available to handle the data corresponding to the first packet,
wherein, in response to receiving the grant cut-through signal, the input port is configured to route the data corresponding to the first packet to the destination output port via the data transport logic, and wherein in response to not receiving the grant cut-through signal, the input port is configured to store the data to the shared memory via the data transport logic, wherein the output port is configured to read the data corresponding to the first packet from the shared memory via the data transport logic in response to having resources available for the data corresponding to the first packet.

5 more elements

Dependencies are inferred from the claim text.

Dynamic selection of lowest latency path in a network switch

Life of this patent

Dynamic selection of lowest latency path in a network switch

Life of this patent

Abstract

Claims54