In this illustration we see six hosts arrayed around three routers, or packet switches. Each packet switch has four ports, or local interfaces. At the center and above all of this is a server, labeled "OpenFlow controller."

The three packet switches are positioned in a triangle shape at the center of the image. The bottom point of the triangle is designated as router s1, the right point of the triangle is designated as s2, and the left point of the triangle is designated as s3. Each router has four numbered ports: port 1 appears at the top left side of the router, port 2 appears at the bottom left side, port 3 appears at the bottom right side, and port 4 appears at the top right side.

In router s1, port 2 connects with Host h1, which has an IP address of 10.1.0.1. Port 3 connects with Host h2, which has an IP address of 10.1.0.2. Port 1 connects with s3's port 3, and port 4 connects with s2's port 2.

In router s2, port 3 connects with Host h3, which has an IP address of 10.2.03. Port 4 connects with Host h4, which has an IP address of 10.2.0.4. Port 1 connects with s3's port 4, and port 2 connects with s1's port 4.

In router s3, port 2 connects with Host h5, which has an IP address of 10.3.0.5. Port 1 connects with Host h6, which has an IP address of 10.3.0.6. Port 3 connects with s1's port 1, and port 4 connects with s2's port 1.

The open flow controller is connected by a dashed line to router s1, router s2, and router s3.