On Demand SDN Slices in ComNetsEmu

This is an academic project for the Softwarized and Virtualized Mobile Networks course at the University of Trento, taught by Prof. Fabrizio Granelli.

Project Goal

The main goal of the project is to implement a network slicing approach to enable dynamic activation/de-activation of network slices via CLI/GUI commands

Setup the environment

The project relies on ComNetsEmu, a testbed and network emulator that already provides all the dependencies we need to start the Ryu application and the MiniNET topology. More information about it can be found here. We personally installed it by cloning the repository and using Vagrant. If installed in this way, the project can be easily started by following these steps:

1. Start the Virtual Machine and get access to a shell
2. Navigate to the directory:

   cd comnetsemu/app/realizing_network_slicing/
   

3. Clone the repository:

   git clone https://github.com/lucademenego99/on-demand-sdn-slices.git
   

4. Move inside the repo directory:

   cd on-demand-sdn-slices
   

5. Start the main ryu application by executing

   sudo ovs-vsctl set-manager ptcp:6632        # Necessary for QoS REST API to work correctly
   ryu run --observe-links ryu_application.py  # Main ryu application
   

6. Open another terminal to create the mininet topology

   sudo ./mesh-network.py
   

This will create a mesh topology with 5 hosts and 5 switches, called respectively h1, h2, h3, h4, h5 and s1, s2, s3, s4, s5.

At this point, in the first terminal you will see the STP protocol in action: when ports are in BLOCK or FORWARD state it means the initialization is completed. From now on, you can:

• try to ping hosts from the mininet console:
  • <host-1> ping <host-2> # ping between two specific hosts
  • pingall # ping all hosts
• check the currently available bandwidth from the mininet console:
  • iperf <host-1> <host-2>
• use the exposed REST API to manage the network (all routes are documented in the next sections)
• use the exposed web application by opening - using a browser - http://localhost:8080.

Web application functionalities

The web application consists of two pages namely, the Homepage and the New slice page. On the Homepage, the user is able to perform the following tasks:

• View the network topology and the configurations of the various switches in case slices have been applied.
• Apply predefined slices, which simulate common network topologies such as Bus, Tree and Star.
• Apply custom slices, which can be created in the New slice page.
• Deactivate applied slices, allowing the network to revert back to a mesh network configuration.

When the user navigates to the New slice he has the following capabilities:

• Create new flow by specifying source and destination hosts.
• Preview the created flow.
• Name the custom slice to make it easier to identify and locate later.
• Save custom slices for future use.

Ryu application components

The ryu application relies on different components exposed by the ryu library, namely:

• ryu.app.rest_qos for handling virtual queues in an easy-to-maintain way;
• ryu.app.ofctl_rest to retrieve and update switch stats;
• ryu.app.rest_conf_switch to set the ovsdb_addr to the switches, essential to create virtual queues;
• ryu.app.rest_topology to get information about the current topology (i.e. hosts, switches and links);
• ryu.app.ws_topology allowing to connect by WebSocket and listen to topology changes;

The main business logic of the application is inside the file switch_stp_rest.py, exposing a switch extended from SimpleSwitch13_stp and a Controller offering the actual REST API.

Some ryu components have been modified a bit to meet this project's requirements, namely the stplib and the main hub.

REST API routes

The list of available endpoints exposed by switch_stp_rest have been defined following the OpenAPI 3.0.0 standard. The YAML file containing the list is available in resources/docs.yaml. Otherwise, after having started the application, a webpage showcasing all endpoints can be accessed at http://localhost:8080/docs/index.html.

As a last alternative, the docs are also served by SwaggerHub: https://app.swaggerhub.com/apis/lucademenego99/on-demand-sdn-slices/1.0.0.

Examples

Get all hosts:

curl -X GET http://127.0.0.1:8080/api/v1/hosts

Activate a slice:

curl -X GET http://127.0.0.1:8080/api/v1/slice/1

Delete a slice:

curl -X DELETE http://127.0.0.1:8080/api/v1/slice/2

Deactivate a slice:

curl -X GET http://127.0.0.1:8080/api/v1/slice/deactivate