"p4alu" is a P4 program designed to parse UDP packets with a specific header format and perform arithmetic calculations. It has been tested using the bmv2 simple_switch P4 target, and the source code is available on GitHub. The document includes details about how to configure and run the program, as well as specific opcodes for addition and subtraction operations.

1. ~ p4alu ~
Arithmetic Logic Unit in P4
Kentaro Ebisawa | Ponto Networks, Inc.
ebiken@pontonetworks.com
Twitter: @ebiken
p4alu ... Arithmetic Logic Unit in P4 | Software Router BoF @ IW2017 Japan | 2017/11/29 1

2. • “p4alu” is an P4 program who would parse UDP packet with
payload in "p4alu header format" and apply calculation.
• This program is tested using BMv2 simple_switch P4 target.
• Source Code on GitHub
• https://github.com/ebiken/p4sandbox/tree/master/p4alu
• Generic P4 information in Japanese （日本語）
• How to Run P4 Behavior Model v2 (JAPANESE)
• https://www.slideshare.net/kentaroebisawa/how-to-run-p4-bmv2
p4alu ... Arithmetic Logic Unit in P4 | Software Router BoF @ IW2017 Japan | 2017/11/29 2
p4alu

3. p4alu ... Arithmetic Logic Unit in P4 | Software Router BoF @ IW2017 Japan | 2017/11/29 3
ALU
Integer
Operand
Integer
Operand
Integer
Result
opCode
op1 op2
result

4. p4alu ... Arithmetic Logic Unit in P4 | Software Router BoF @ IW2017 Japan | 2017/11/29 4
p4alu header format
Integer
Operand
Integer
Operand
Integer
Result
opCode
op1 op2
result

5. p4alu ... Arithmetic Logic Unit in P4 | Software Router BoF @ IW2017 Japan | 2017/11/29 5
P4 parser

6. p4alu ... Arithmetic Logic Unit in P4 | Software Router BoF @ IW2017 Japan | 2017/11/29 6
P4 action

7. p4alu ... Arithmetic Logic Unit in P4 | Software Router BoF @ IW2017 Japan | 2017/11/29 7
P4 table & control

8. p4alu ... Arithmetic Logic Unit in P4 | Software Router BoF @ IW2017 Japan | 2017/11/29 8
Setup netns based hosts
BMv2 running p4alu

9. p4alu ... Arithmetic Logic Unit in P4 | Software Router BoF @ IW2017 Japan | 2017/11/29 9
Compile and Run on BMv2

10. p4alu ... Arithmetic Logic Unit in P4 | Software Router BoF @ IW2017 Japan | 2017/11/29 10
Configure Tables via runtime_CLI
Forward Packet
from/to port#0 <-> port#1
Apply action based on opCode
• opCode: 1 => p4alu_add
• opCode: 2 => p4alu_sub
BMv2 Runtime CLI command format

11. p4alu ... Arithmetic Logic Unit in P4 | Software Router BoF @ IW2017 Japan | 2017/11/29 11
Packet Format (sending from host0)
• opCode: 0x01 => p4alu_add
• opCode: 0x02 => p4alu_sub

12. CuiShark by @slankdev | https://github.com/slankdev/cuishark
p4alu ... Arithmetic Logic Unit in P4 | Software Router BoF @ IW2017 Japan | 2017/11/29 12
packets after going through p4alu
op1 opCodeop2 result

13. CuiShark by @slankdev | https://github.com/slankdev/cuishark
p4alu ... Arithmetic Logic Unit in P4 | Software Router BoF @ IW2017 Japan | 2017/11/29 13
packets after going through p4alu
op1 opCodeop2 result