Log Directory Location

• Within the Docker container, p4app saves log files to /tmp/p4app-logs.
• By default, /tmp/p4app-logs is mounted from /tmp/p4app-logs on the host machine.
• The log directory location can be overridden by specifying the P4APP_LOGDIR env variable.
  • e.g., mkdir ~/mylogs, then P4APP_LOGDIR=~/mylogs ~/p4app/p4app run .

The BMv2 Log

• Each switch logs to /tmp/p4app-logs/p4s.XXX.log, where XXX is the name of the switch.
  • e.g., the log for switch s1 will be in /tmp/p4app-logs/p4s.s1.log.

PCAP Files

• By default, BMv2 dumps all packets received/sent by the switches to PCAP files in the log directory (/tmp/p4app-logs).
• For each switch, there are two PCAP files per port: packets sent by the switch (*_in.pcap), and received (*_out.pcap).
  • e.g., /tmp/p4app-logs/s1-eth2_out.pcap contains the packets sent by s1 on port 2.
• Tip: use mergecap for viewing both PCAPs together: mergecap -w tmp.pcap /tmp/p4app-logs/s1-eth2_* && wireshark tmp.pcap

Mininet Console

• You can launch a Mininet console from the p4app entry point (main.py).
• The console can be used for inspecting Mininet, for example:
  • Show the interfaces for switch s1: mininet> py s1.intfs
  • Show help: mininet> help
• This can also be used to run commands on hosts:
  • Print interface status: mininet> h1 ifconfig
  • Send a ping packet from h1: mininet> h1 ping -c1 10.0.0.1

Running Commands Inside p4app

• Once you have launched a p4app, you can interact with it from another terminal
• The p4app exec command lets you run a program within the container of the most recently launched p4app.
  • Open a shell in the container: ~/src/p4app/p4app exec bash
  • Open a shell on a Mininet host within container: ~/src/p4app/p4app exec m h1 bash