multicast

Multicast

+--+      +--+     ++-+
|h1+------+  +-----+h2+
+--+      +  +     +--+
          +s1+
+--+      +  +     ++-+
|h3+------+  +-----+h4+
+--+      +-++     +--+

Introduction

In this example we show how to use the multicasting engine to broadcast packets to all the ports of the switch.

In this very simple example we create a multicast group that sends packets to all the four ports. Thus, the packet to broadcast will be sent back to the port it came in. To avoid that, you can create a multicast group for each ingress port, and then use it accordingly.

Note: Only packets with an ethernet type of 0x1234 get multicasted to all the ports.

You can find more information about how to create multicast groups in the following documentation section.

How to run

Run the topology:

sudo p4run

or

sudo python network.py

Send traffic with the special ethernet type using the send.py script.

mx h1
python send.py

Monitor all the interfaces and see that for each packet that is sent from h1 four packets get replicated.

sudo tcpdump -i s1-eth2 -Q out
sudo tcpdump -i s1-eth3 -Q out
sudo tcpdump -i s1-eth4 -Q out