A Time-Sensitive Network Switch Implementation using Programming Protocol-Independent Packet Processors (P4)

Introduction

Final year research project to design a programmable virtual switch based on the specifications of TSN to be implemented on a TSN network (in Mininet) comprised of various TSN switches and a network controller.

The research project is submitted to the Department of Electrical Engineering at the University of Cape Town in partial fulfilment of the academic requirements for a Bachelor of Science degree in Electrical Engineering

Instructions

The TSN switch and the network designed are implemented on Mininet using P4. P4 is a high-level network programming language that defines packet-processing pipelines and forwarding rules on programmable switches. The network is comprised of three V1model architectural P4 BMv2 software switches, five hosts (h1,h2,h3,h11, and h22) and a P4Runtime controller. The network topology is shown below:

How it works

1. P4 program is written to define packet forwarding rules in the switches. This program is found in the file: TSN_Switch.p4

2. The P4 program rules have to be inserted to the tables by the control plane. These rules are installed in each table by making use of Mininet instance make run command.

3. P4runtime is used to install these control plane rules to each switch. The rules can be found on the following files: s1-runtime.json, s2-runtime.json & s3-runtime.json.

4. In order to be able to use priority queueing on the BMv2 switches, changes have to be made on the v1model.p4 by adding @alias("intrinsic_metadata.priority") bit<3> priority; inside the metadata field struct.

How to run results

Basic IP Routing

1. Use terminal to cd in the with the P4 file, eg: cd /home/p4/A Time-Sensitive Network Switch Implementation using P4/TSN_Switch.
2. Run the following command:

• make run

3. The command will compile TSN_Switch.p4 and start the topology in Mininet and configure all switches with the appropriate P4 program and table entries, and configure all hosts with the commands listed in the file topology.json.
4. A Mininet command prompt will appear, build topology and configure all the switch.
5. In the Mininet command line, open three xterm h1, h2, h3 as follows:

• xterm h1 h2 h3

6. On xterm h2 & h3, run the following command:

• ./receive.py

This command runs the python server to sniff and and print packets that arrives on h2 & h3

7. On xterm h1 run the following commands:

• ./send.py 10.0.2.2 “Implementing TSN switch using P4 has been fun”
• ./send.py 10.0.3.3 “Thanks to my supervisor Dr JM”

These commands will send packets to h2 & h2 with the indicated messages.

Tunneling

The results for this test follow similar instructions as the basic IP routing except host h1 sending command line. With tunneling, xterm h1 use the following commands:

• ./send.py 0.0.0.0 “Tunneling uses destination ID” --dst_id 2
• ./send.py 1.1.1.1 “Tunneling ignores IP address" --dst_id 3

With tunneing, the destination address is not relevant because this is not IP routing but packets are forwarded based on the customized tunnel header IDs.

P4Runtime-Controlled TSN Network

This experiment performed tests to check whether TSN operational specifications are achieved by the network.

Here four xterms h1, h2, h11, and h22 were opened.

1. To get the results for communication between low priority talker (h1) and low priority listener (h2) h1 ->h2, the following commands are performed on xterm h1 and h2:

• h1: iperf -c 10.0.2.2 -i 1 -t 60 -u -b 10M

• this command instructs h1 to act as a client (-c) and send UDP (-u) packets with bandwidth size of 10Mbits/sec (-b 10M) to destination with IP address 10.0.2.2 (-c 10.0.2.2) and print results every 1 second (-i 1) for 60 seconds (-t 60)

• h2: iperf -s -u -i 1

• This instruct h2 to act as server (-s) and listen/sniff UDP packets and print results every 1 second (i- 1).

2. Similarly, To get the results for communication between high priority talker (h11) and hign priority listener (h22) h11 ->h22, the following commands are performed on xterm h11 and h22:

• h1: iperf -c 10.0.2.22 -i 1 -t 15 -u -b 0M && iperf -c 10.0.2.22 -i 1 -t 30 -u -b 10M && iperf -c 10.0.2.22 -i 1 -t 15 -u -b 0M

This command instructs h1 to act as a client (-c) and send UDP (-u) packets with bandwidth size of 0Mbits/sec (-b 0M) to destination with IP address 10.0.2.22 (-c 10.0.2.22) and print results every 1 second (-i 1) for 15 seconds (-t 15)

and send UDP (-u) packets with bandwidth size of 10Mbits/sec (-b 10M) to destination with IP address 10.0.2.22 (-c 10.0.2.22) and print results every 1 second (-i 1) for 30 seconds (-t 30)

and send UDP (-u) packets with bandwidth size of 0Mbits/sec (-b 0M) to destination with IP address 10.0.2.22 (-c 10.0.2.22) and print results every 1 second (-i 1) for 15 seconds (-t 15)

• h22: iperf -s -u -i 1

This instruct h22 to act as server (-s) and listen/sniff UDP packets and print results every 1 second (i- 1).

3. Finally, the results obtained for each of the test can be found above, folder Plots Results and these are the results used to perform the plots.