Implementing Tunneling with P4

Introduction

In this exercise, we will add support for a tunneling to routers. Your job is to change the P4 code to have the switches add the myTunnel header to an IP packet upon ingress to the network and then remove the myTunnel header as the packet leaves to the network to an end host. You have to define a new header type to encapsulate the IP packet and modify the switch code, so that it instead decides the destination port using a new tunnel header. The new header type will contain a protocol ID, which indicates the type of packet being encapsulated, along with a destination ID to be used for routing.

• Start early and feel free to ask questions on Github and CW.
• You can also stop by Performance and Dependability Lab (PDL) (Room #815, CE Dep) with prior appointment.

Obtaining required software

1. Follow the instructions in P4 lang tutorials and install the required VM.
2. install iperf3 on the VM.

  sudo apt-get install iperf3

3. On the VM, cloen this repository

    git clone -b spring-2022 https://github.com/arshiarezaei/course-net.git

Step 1: Implement Tunneling

A complete implementation of the basic_tunnel.p4 switch will be able to forward based on the contents of a custom encapsulation header as well as perform normal IP forwarding if the encapsulation header does not exist in the packet.

1. NOTE: A new header type has been added called myTunnel_t that contains two 16-bit fields: proto_id and dst_id.
2. NOTE: The myTunnel_t header has been added to the headers struct.

Step 2: Implement ACL for the Switch s3

In the switch s3 you must also add a simple access control list (ACL) that simply drops every packet with UDP destination port == 80 and ipv4 dstAddress==10.0.3.3.

Important: if you hard code ACL roles in the data plane you lose some points.

Step 3: Add Forwarding Table Enteries

A P4 program defines a packet-processing pipeline, but the rules within each table are inserted by the control plane. When a rule matches a packet, its action is invoked with parameters supplied by the control plane as part of the rule.

For this exercise, you have to added the necessary rules to sX-runtime.json.

Important: You will be asked to modify the forwarding behavior of the control plane.

Step 3: Run your solution

1. In your shell, run:

   make run

   This will:

   • compile tunnel.p4 and acl_tunnel.p4
   • start a Mininet instance with three switches (s1, s2, s3) configured in a triangle, each connected to one host (h1, h2, and h3).
   • The hosts are assigned IPs of 10.0.1.1, 10.0.2.2, and 10.0.3.3.

2. You should now see a Mininet command prompt. Open two terminals for h1 and h2, respectively:

mininet> xterm h1 h2

3. Each host includes a small Python-based messaging client and server. In h2's xterm, start the server:

./receive.py

4. First we will test without tunneling. In h1's xterm, send a message toh2:

./send.py 10.0.2.2 "P4 is cool"

The packet should be received at h2. If you examine the received packet you should see that is consists of an Ethernet header, an IP header, a TCP header, and the message. If you change the destination IP address (e.g. try to send to 10.0.3.3) then the message should not be received by h2, and will instead be received by h3.

5. Type exit or Ctrl-D to leave each xterm and the Mininet command line.

Cleaning up Mininet

In the latter two cases above, make may leave a Mininet instance running in the background. Use the following command to clean up these instances:

make stop

Policy

If you violate any of the following rules, you will get 0 for this assignment.

1.You must complete this assignment individually.
2.You are not allowed to share your code (or a peace of it) with other students.
3.If you use code on the internet you should cite the source(s).

Submission

You must submit:

• Your source code for the exercises, in a folder called P4-assignment and submit an assignment2.zip file. Make sure to submit both the p4 code and the corresponding json file that configures the table entries.