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See README-using-bmv2.md for some things that are common across different P4 programs executed using bmv2.

To compile the P4_16 version of the code:

p4c --target bmv2 --arch v1model demo2.p4_16.p4

To compile the P4_14 version of the code:

p4c --std p4-14 --target bmv2 --arch v1model demo2.p4_14.p4

The .dot and .png files in the subdirectory 'graphs' were created with the p4c-graphs program, which is also installed when you build and install p4c-bm2-ss:

p4c-graphs -I $HOME/p4c/p4include demo2.p4_16.p4

The '-I' option is only necessary if you did not install the P4 compiler in your system-wide /usr/local/bin directory.

To run the behavioral model with 8 ports numbered 0 through 7:

sudo simple_switch --log-console --dump-packet-data 10000 -i 0@veth0 -i 1@veth2 -i 2@veth4 -i 3@veth6 -i 4@veth8 -i 5@veth10 -i 6@veth12 -i 7@veth14 demo2.p4_16.json

To run CLI for controlling and examining simple_switch's table contents:

simple_switch_CLI

General syntax for table_add commands at simple_switch_CLI prompt:

RuntimeCmd: help table_add
Add entry to a match table: table_add <table name> <action name> <match fields> => <action parameters> [priority]

You can find more comprehensive documentation about the table_add and table_set_default commands here and here, but you do not need to know all of that to understand and use the example commands here.

simple_switch_CLI commands for demo2 program

demo2.p4_16.p4 only

The table_set_default commands without the ingressImpl. and egressImpl. prefixes before drop_with_count and my_drop used to work for the P4_16 version of this program, but starting some time around June 2019 this is no longer the case.

table_set_default ipv4_da_lpm ingressImpl.drop_with_count
table_set_default mac_da ingressImpl.my_drop
table_set_default send_frame egressImpl.my_drop

demo2.p4_14.p4 only

table_set_default ipv4_da_lpm my_drop
table_set_default mac_da my_drop
table_set_default send_frame my_drop

demo2.p4_14.p4 or demo2.p4_16.p4 (same commands work for both)

Add both sets of entries below:

table_add ipv4_da_lpm set_l2ptr 10.1.0.1/32 => 58
table_add mac_da set_bd_dmac_intf 58 => 9 02:13:57:ab:cd:ef 2
table_add send_frame rewrite_mac 9 => 00:11:22:33:44:55

table_add ipv4_da_lpm set_l2ptr 10.1.0.200/32 => 81
table_add mac_da set_bd_dmac_intf 81 => 15 08:de:ad:be:ef:00 4
table_add send_frame rewrite_mac 15 => ca:fe:ba:be:d0:0d

You should be able to examine counter values in the counter named ipv4_da_lpm_stats using the counter_read command, which takes the counter name and a handle id. Because ipv4_da_lpm_stats is declared direct on table ipv4_da_lpm, and thus contains one entry for every one in ipv4_da_lpm, use the handle id for the corresponding ipv4_da_lpm table entry that you want stats for.

[ There was a bug with some versions of p4c that prevents counter_read commands from succeeding, roughly corresponding to p4c source code from 2017-Nov-07 until 2017-Nov-20.

The "ingressImpl." prefix in the output of some commands below appears when using the P4_16 version of the program, but not the P4_14 version, due to how p4c names instances based upon the hierarchy of controls they are instantiated within. ]

RuntimeCmd: counter_read ipv4_da_lpm_stats 0
this is the direct counter for table ingressImpl.ipv4_da_lpm
ipv4_da_lpm_stats[0]=  BmCounterValue(packets=1, bytes=54)

After sending another packet matching the same ipv4_da_lpm entry, reading the counter entry gives different values:

RuntimeCmd: counter_read ipv4_da_lpm_stats 0
this is the direct counter for table ingressImpl.ipv4_da_lpm
ipv4_da_lpm_stats[0]=  BmCounterValue(packets=2, bytes=108)

The command counter_reset <name> clears all counters in the named collection of counters.

RuntimeCmd: counter_reset ipv4_da_lpm_stats
this is the direct counter for table ingressImpl.ipv4_da_lpm

RuntimeCmd: counter_read ipv4_da_lpm_stats 0
this is the direct counter for table ingressImpl.ipv4_da_lpm
ipv4_da_lpm_stats[0]=  BmCounterValue(packets=0, bytes=0)

scapy session for sending packets

I believe we must run scapy as root for it to have permission to send packets on veth interfaces.

$ sudo PATH=$PATH VIRTUAL_ENV=$VIRTUAL_ENV python3
from scapy.all import *

fwd_pkt1=Ether() / IP(dst='10.1.0.1') / TCP(sport=5793, dport=80)
drop_pkt1=Ether() / IP(dst='10.1.0.34') / TCP(sport=5793, dport=80)

# Send packet at layer2, specifying interface
sendp(fwd_pkt1, iface="veth0")
sendp(drop_pkt1, iface="veth0")

fwd_pkt2=Ether() / IP(dst='10.1.0.1') / TCP(sport=5793, dport=80) / Raw('The quick brown fox jumped over the lazy dog.')
sendp(fwd_pkt2, iface="veth0")

Last successfully tested with these software versions

For https://github.com/p4lang/p4c

$ git log -n 1 | head -n 3
commit fcfb044b0070d78ee3a09bed0e26f3f785598f02
Author: Radostin Stoyanov <rstoyanov@fedoraproject.org>
Date:   Tue Dec 20 16:08:09 2022 +0000

For https://github.com/p4lang/behavioral-model

$ git log -n 1 | head -n 3
commit e97b6a8b4aec6da9f148326f7677f5e46b09e5ee
Author: Radostin Stoyanov <rstoyanov@fedoraproject.org>
Date:   Mon Dec 12 21:05:06 2022 +0000