This project consists of developing an SDN-based network that implements an Asynchronous Message Delivery (AMD) System. An AMD is a communication model based on the store-and-forward technique that allows a client to send messages to a server that can be temporarily offline. This results in decoupling the client and the server.

So, in the system can be identified two different entities: the client which sends the messages and the server that receives and consumes them. To this aim, the server needs to subscribe itself to the AMD system that will assign it a virtual IP and MAC. These addresses can be used by the client to contact it. During the lifetime of the server in the system, it can change its status from online to offline. In this case the system has to buffer the incoming messages and resend them to it as soon as it is back online. Instead, if the server is online, all client requests are delivered synchronously.

The server uses the REST APIs exposed by the system to subscribe/unsubscribe and to update its status. Moreover, in a real case multiple servers are subscribed so even the client can use the REST APIs to retrieve information about them.

The AMD system has been simulated using Mininet that allows to create a realistic virtual network, running real kernel, switch and application code. The network is composed by Open vSwitch (OVS) instances that are open-source implementation of a distributed virtual multi-layer switches, supporting the OpenFlow protocol to communicate with the SDN controller. The latter is provided by a Java framework called Floodlight that is an implementation of an OpenFlow controller.

Firstly, it's necessary to clone the official Floodlight repository and this repository:

git clone https://github.com/floodlight/floodlight.git floodlight
git clone https://github.com/biagiocornacchia/Asynchronous-Message-Delivery amd

Then, copy the amd/src/forwarding and amd/src/unipi folders into floodlight/src/main/java/net/floodlightcontroller/. Finally, remember to add net.floodlightcontroller.unipi.amd.AsynchronousMessageDelivery in the floodlightdefault.properties and IFloodlightModule files.

The module can be tested in a simulated environment like Mininet. In particular, the amd/scripts folder contains two python scripts that create two different virtual networks. These scripts require the mininet package for python. Before starting one of the scripts, the floodlight controller must already be running.

To use the REST APIs, a browser extension like Boomerang SOAP and REST Client can be used. The endpoints exposed by the module are:

POST http://<CONTROLLER_IP>:8080/amd/server/subscription/json
DELETE http://<CONTROLLER_IP>:8080/amd/server/subscription/json
PUT http://<CONTROLLER_IP>:8080/amd/server/status/json
GET http://<CONTROLLER_IP>:8080/amd/server/info/json

More information on how to build a request can be found in the project report.

• Biagio Cornacchia, [email protected]
• Matteo Abaterusso, [email protected]