DPTP

Data-Plane Time synchronization Protocol (https://www.comp.nus.edu.sg/~pravein/papers/DPTP_SOSR19.pdf) This source code synchronizes two Barefoot Tofino switches to support a global timing (64-bit) in the data-plane.

p4_14 : v_14/ (Tested on SDE 8.x.x)

p4_16 : v_16/ (Tested on SDE 9.x.x)

Topology

The Topology used in as below :

A single tofino switch named "tofino1" is virtualized into two switches Master(M) and Switch1. To do this virtualization, you will need to add a loopback link between port3 (160-163) and port5 (176-179). Once done, it will be configured as 10G ports, and we will be using only one link (160-176) as the connection between Switch1 and Master. Additionally, you will need atleast one host connected to port 1(128-131) to send DPTP requests.

Steps to run p4_14 based DPTP in Tofino:

1. Navigate to the SDE PATH :

     cd ~/bf-sde-8.x.x
     export DPTP_PATH=<PATH TO DPTP FOLDER>

2. Set the env variables :

     . ./set_sde.bash

3. Build the p4 program using the command :

     ./p4_build.sh $DPTP_PATH/v_14/dptp_topo.p4

4. Load the p4 program, and run the control plane API code using :

     "cd $DPTP_PATH/v_14/CP"
     "./run.sh"

5. This should automatically start the synchronization between Switch1 and master through packets from control-plane.

Steps to run p4_16 based DPTP in Tofino:

1. Navigate to the SDE PATH :

     cd ~/bf-sde-9.x.x
     export DPTP_PATH=<PATH TO DPTP FOLDER>

2. Set the env variables :

     . ./set_sde.bash

3. DPTP program in p4_16 has multiple profiles :

   a) DPTP with logical switches to get measurements and to do a sanity check.

        ./p4_build.sh -DLOGICAL_SWITCHES $DPTP_PATH/v_16/p4_src/dptp.p4

   b) DPTP without logical switches. This is basically the program that can be included in any p4 programs

        ./p4_build.sh $DPTP_PATH/v_16/p4_src/dptp.p4

4. Load the p4 program, and run the control plane API code using :

     "cd $DPTP_PATH/v_16/CP"
     "./run.sh"

5. This should automatically start the synchronization between Switch1 and master through packets from control-plane.

Steps to run MoonGen for host synchronization:

Moongen script sends synchronization requests packets between switches Pull from https://github.com/praveingk/moongen/, Make sure the submodule libmoon is also pulled. Follow the readme instructions in moongen to build it.

1. Enable the NIC to work with DPDK:

sudo ./libmoon/deps/dpdk/usertools/dpdk-devbind.py --b igb_uio <NIC Port>

2. To start DPTP in the network between switch 1 and master:

 sudo ./build/MoonGen examples/dptp_topo.lua <DPDK PORT id1> <DPDK Port id2>

Note that "DPDK Port id2" is redundant and is used only for switch-to-host DPTP accuracy measurement.

Steps to Create CrossTraffic in the Link(160-176) during DPTP

1. To create cross-traffic in the link being used for synchronization towards the SW1 (i.e. 160 --> 176), we simply craft a packet to destination address of SW1 (0x100000000001) and send it from any host link.

 sudo ./build/MoonGen examples/dptp_topo.lua -d 1 <DPDK PORT id1> <DPDK Port id2>

Note that "DPDK Port id2" is redundant and is used only for switch-to-host DPTP accuracy measurement.

2. To create oversubscribed traffic, run the above example from two 10G host-links.