Methods and apparatus for alleviating congestion at a switch, such as a shallow buffered switch

A computer-implemented method for handling network traffic surges at a shallow-buffered switch, the computer-implemented method comprising:

• a) receiving by the switch, a packet;
• b) extracting a destination information from the packet;
• c) performing an IP lookup, using the extracted destination information, to determine an output port of the switch;
• d) querying an active queue management (AQM) module of the output port for a redirection probability between 0 and 1;
• e) receiving from the AQM module a redirection probability between 0 and 1;
• f) generating a uniform random floating point number for the packet;
• g) determining to redirect the packet when r≦q, where r is the random number and q is the retrieved redirection probability, and otherwise, not determining to redirect the packet;
• and
• h) responsive to a determination to redirect the packet, forwarding the packet to a dedicated reservoir port of the switch to effect a redirection of the packet to a reservoir, and otherwise, responsive to a determination to not redirect the packet, not forwarding the packet to the reservoir.

A computer-implemented method for handling network traffic surges at a shallow-buffered switch, the computer-implemented method comprising:

• a) receiving by the switch, a packet;
• b) extracting a destination information from the packet;
• c) performing an IP lookup, using the extracted destination information, to determine an output port of the switch;
• d) querying an active queue management (AQM) module of the output port for a redirection probability between 0 and 1;
• e) receiving from the AQM module a redirection probability between 0 and 1;
• f) extracting from the packet, transport layer flow information;
• g) mapping, using a hash function, the extracted transport layer flow information to a pseudo-random number within a hash range of the hash function;
• h) calculating a redirection region with the hash range based on the received redirection probability;
• i) determining to redirect the packet responsive to a determination that the pseudo-random number corresponding the received packet is within the redirection region, and otherwise, responsive to a determination that the pseudo-random number corresponding to the received packet is not within the redirection region, not determining to redirect the packet;
• and
• j) responsive to a determination to redirect the packet, forwarding the packet to a dedicated reservoir port of the switch to effect a redirection of the packet to a reservoir, and otherwise, responsive to a determination to not redirect the packet, not forwarding the packet to the reservoir.

A reservoir for relieving network traffic surges at an external shallow-buffered switch having a plurality of output ports and at least one reservoir port, reservoir comprising:

• a) at least one input port for receiving redirected packets dispatched from the at least one reservoir port of the external switch;
• b) at least one output port for sending redirected packets back to the external switch;
• c) a plurality of internal queues, each of the plurality of internal queues
• 1) corresponding to one of the plurality of output ports of the external switch, and
• 2) temporarily buffering those of the received redirected packets from the external switch that were destined for the corresponding output port of the external switch, and
• d) a scheduler including
• 1) a plurality of cushion buffers, each of the cushion buffers
• A) corresponding to one of the plurality of internal queues, and
• B) having a capacity that is smaller than its corresponding internal queue,
• 2) a plurality of first arbiters, each of the first arbiters
• A) corresponding to one of the plurality of internal queues, and
• B) configured for deciding when to send packets from its corresponding queue to the corresponding cushion buffer in a paced manner such that collisions and congestion at an output port of the external switch is relieved, the scheduler, and
• 3) a second arbiter adapted to schedule forwarding of redirected packets from the plurality of cushion buffers to the at least one output port.