In this tutorial, we will set up a simple network topology that simulates a load balancer using eBPF/XDP (Express Data Path). The setup includes a local machine, a load balancer (which can be enhanced with an XDP program), and two backend servers (h2 and h3). The local machine routes packets to the load balancer, which then distributes traffic between the backend servers.

Simple XDP Load Balancer Tutorial

This tutorial will guide you in setting up a simple virtual network to simulate a load balancer using eBPF/XDP.

Network Topology

   +------------------+
   |  Local Machine   |
   |  IP: 10.0.0.1    |
   +--------+---------+
            |
   +--------+---------+
   |   Load Balancer  |
   |  IP: 10.0.0.10   |
   +--------+---------+
            |
    +-------+-------+
    |               |
+---+---+       +---+---+
|  h2   |       |  h3   |
|10.0.0.2|       |10.0.0.3|
+-------+       +-------+

• Local Machine: Simulates a client (10.0.0.1) sending traffic.
• Load Balancer: Distributes traffic to backend servers (10.0.0.10).
• h2 and h3: Simulate backend servers (10.0.0.2 and 10.0.0.3).

Setup Steps

This script creates virtual network namespaces and sets up IP addresses for the local machine, load balancer, and backend servers.

sudo ./setup.sh

To clean up the setup after testing:

sudo ./teardown.sh

Testing the Network

You can test the network connectivity using ping commands:

Ping Between Backend Servers (h2 to h3)

sudo ip netns exec h2 ping -c 3 10.0.0.3

Ping from Backend Server (h2) to Load Balancer

sudo ip netns exec h2 ping -c 3 10.0.0.10

Ping from Local Machine to Load Balancer

ping -c 3 10.0.0.10

That's it! This simple setup lets you simulate a load balancer using eBPF/XDP. You can extend it by adding custom XDP programs to control the traffic distribution between h2 and h3.