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DPTP (Data-Plane Time synchronization Protocol)

This source code synchronizes the network consisting of programmable (Barefoot Tofino) switches and IEEE1588 PTP-compatible NICs to support the global timing (64-bit) in the network data-plane (Switch and NICs). Once DPTP is running, packets can have a global timing context, which is useful for several applications like latency tracking, monitoring, updates, ordering of events, distributed applications, etc.

Paper Link 👉 https://dl.acm.org/doi/10.1145/3314148.3314353?cid=82658740957

Source Code Pointers

Switch Code

The switch data-plane code is written in P4 programming language. Once this code is up and running, two virtual switches are synchronized to a global time.

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

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

End-Host Code

dptpclient : Once Switches are synchronized, end-hosts connected to the switch could run the dpdk-based dptpclient to synchronize end-hosts/nic with the network time.

Topology

The Topology used in as below :

DPTP Topology

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>
  1. Set the env variables :
     . ./set_sde.bash
  1. Build the p4 program using the command :
     ./p4_build.sh $DPTP_PATH/v_14/dptp_topo.p4
  1. Load the p4 program, and run the control plane API code using :
     cd $DPTP_PATH/v_14/CP
     ./run.sh
  1. 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>
  1. Set the env variables :
     . ./set_sde.bash

  1. 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

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

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

If you want to enable debugs the command is :

     ./run.sh debug
  1. This should automatically start the synchronization between Switch1 and master through packets from control-plane.

Steps to run DPTPClient for host synchronization:

Refer Readme

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 Ports>
  1. To start DPTP in the network between switch 1 and master:
 sudo ./build/MoonGen examples/dptp_host.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_host.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.

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