NetFPGA switch with INT mirroring, early drop for special packets, and dynamic threshold

This repo provides a switch with:

INT mirroring

Each packet will be mirrored (only the header part), with some fields in the header modified to store the queueing-related variables, such as queue length, drop or not.

The collector of the mirrored packets is in another repo: TCP_replay_testbed. See TCP_replay_testbed/runtime_capture.
Early drop for special packets

A packet with some bit marked 1 will be dropped early: if the queue_lenght > threshold-3*MAX_PACKET_SIZE, drop the packet.
Dynamic threshold

Modified code

lib/hw/std/cores/output_queues_v1_0_0/
	output_queues.tcl
	hdl/output_queues.v
lib/hw/std/cores/fallthrough_small_fifo_twothresh_v1_0_0 (new dir)

the .old files under the above two dirs is the version with only INT mirroring and early drop. The corresponding .v files are based on the .old files and adding dynamic threshold.

Detail

INT mirroring

The output_queue is the module for output queue, which originally calls fallthrough_small_fifo.

We change it to call fallthrough_small_fifo_twothresh, which exposes the queue length. We put the queue length in the mirrored packet header. The mirroring port is numbered 0.
Early drop

The fallthrough_small_fifo_twothresh also takes another threshold called PROG_FULL_THRESHOLD_EARLY. It compares the queue length with this early threshold, and returns whether the early threshold is reached (prog_full in small_fifo_twothresh). output_queue module takes prog_full and the 120-th bit (0-th bit of tos field) in packet, and decides whether to drop the packet (prog_full == 1 and 120-th bit == 1) or not.
Dynamic threshold

The fallthrough_small_fifo_twothresh and small_fifo_twothresh expose the current queue length to output_queue. output_queue uses the queue lengths to calculate the dynamic threshold (real_threshold in output_queue.v), and assign the dynamic threshold back to fallthrough_small_fifo_twothresh and small_fifo_twothresh for them to decide whether the threshold is reached or not (prog_full (early drop) and nearly_full (normal drop)).

Note that the both prog_full and nearly_full are based on the dynamic threshold, not the configured PROG_FULL_THRESHOLD and PROG_FULL_THRESHOLD_EARLY. These two configurations are not used.

Usage

Compile

You may follow SUME official guideline (https://github.com/NetFPGA/NetFPGA-SUME-public/wiki/Projects) to get started.

Specifically, if you issue make in the top dir ([root@nf-test109 NetFPGA-SUME-live]# make), this will build all the basic modules.

Next, you will need to build other modules manually. First, issue make in the lib/hw/xilinx/cores/cam_v1_1_0 and lib/hw/xilinx/cores/tcam_v1_1_0 to build CAM and TCAM modules (please refer this: https://github.com/NetFPGA/NetFPGA-SUME-public/wiki/NetFPGA-SUME-TCAM-IPs). Second, every time you add or modify the code of some modules (like we did in the step 3 above), you need to go to that specific module and rebuild it. For example, you will issue [root@nf-test109 NetFPGA-SUME-live\lib/hw/std/cores/fallthrough_small_fifo_twothresh_v1_0_0]# make).

Last, issue make in projects/reference_switch to build the project, which will leverage all the necessary modules you just built.

Again, everytime make a change to a modules under lib/hw/std/cores/, just do make under the dir of the module, and make in projects/reference_switch.

Change dynamic threshold

Change BIT_SHIFT_ALPHA in lib/hw/std/cores/output_queues_v1_0_0/hdl/output_queues.v to change the alpha of dynamic thresholding.