recirculate

Basic Recirculation

+--+      +--+     ++-+
|h1+------+s1+-----+h2+
+--+      +-++     +--+

Introduction

In this example we show how to recirculate packets.

The program itself does nothing. It just recirculates all packets 5 times and finally sends them to port 2. You can see that we use metadata structs to carry the recirculate counter in order to track how many times the packet has been recirculated.

The program also shows you a trick to debug programs. De debugging trick uses a table to match some fields so their value gets displayed in the log file (log/s1.log).

How to run

Start topology:

sudo p4run

or

sudo python network.py

Send some traffic. And then check the log file at log/s1.log, you will see how the counter increases at each recirculation when matching the debug table.