ip_forwarding

Implementing Basic Forwarding

                   +--+
                   |h4|
                   ++-+
                    |
                    |
+--+      +--+     ++-+     +--+
|h1+------+s1+-----+s3+-----+h3|
+--+      +-++     +--+     +--+
            |
            |
          +-++
          |s2|
          +-++
            |
            |
          +-++
          |h2|
          +--+

Introduction

The objective of this exercise is to write a P4 program that implements basic forwarding. To keep things simple, we will just implement forwarding for IPv4.

With IPv4 forwarding, the switch must perform the following actions for every packet: (i) update the source and destination MAC addresses, (ii) decrement the time-to-live (TTL) in the IP header, and (iii) forward the packet out the appropriate port.

Your switch will have a single table, which the control plane will populate with static rules. Each rule will map an IP address to the MAC address and output port for the next hop. We have already defined the control plane rules, so you only need to implement the data plane logic of your P4 program.

How to run

Run the topology:

sudo p4run

or

sudo python network.py

Try to ping from one host to another:

mininet> h1 ping h2

Ping from all host pairs to test for connectivity:

mininet> pingall