SymPyNet

A framework written in Python for the simulation at each level of the TCP/IP suite protocols.

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Description of the project

SimPyNet is a composition of three words that characterise the project

1. Simulator
2. Python
3. Network

simpynet is a framework totally written in Python,it is able to simulate the mechanism at any level of the TCP/IP protocol suite model (physical,link, network, transport, application).

simpynet is based on the DES (Discrete-Event-Simulation) simulation model. The simulator doesn't provide a GUI (such as other simulator GNS3,OMNeT++) but is recommended for teaching purpose, because are required programming skills.

simpynet provides a logging mechanism and collectors machanism. The first is utilized for logging the information during the exectution of the simulation the latter for collectiong parameters in order to realize statistical analysis.

simpynet was born as support theaching software for the course of Computer Network at University of Florence.

Requirements

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• Python 2.7
• simpy

Install in a virtual environment

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1. Download the archive of the latest release X.Y
2. Unpack the archive name tar -xzf simpynet-X.Y.tar.gz (or zip) and will unpack into a directory simpynet-x.y
3. Create a virtualenv and activate it with the command source /path_to_venv/bin/activate
4. Enter in the simpynet-x.y directory and run the command python setup.py install

Write the first simulation

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This program simulate a DHCP client and DHCP server interaction: the client asks for an IP address and the server will send the rigth one.

Create a new file called prova.py and paste inside the followed code.

import simpynet as spn


def DHCP_network( env ):

    """
    |dhcp_client|------link 1------ |dhcp_server|
    """
    # creates the two Host: client and server with their own MAC and IP address
    c_host = spn.Host( env, spn.Mac('aa.aa.aa.aa.aa.aa'),  spn.IP('0.0.0.0') )
    s_host = spn.Host( env, spn.Mac('bb.bb.bb.bb.bb.bb'),  spn.IP('192.168.1.1') )
    
    # create a Link1 with propagation delay and trasmission delay one
    l1 = spn.Link(env, lambda x,y: 1 , lambda src,trg,l: 1)
    
    #plugs the link to the host server and the host client
    spn.physical.plug( l1 , c_host )
    spn.physical.plug( l1 , s_host )

    # wrap the general HOst in the DHCP client and server
    client=spn.DHCP_client( env , c_host )
    server=spn.DHCP_server( env , s_host )

    # function exeuted by the client to choose the DHVP server
    def choose_ip_server( lista_ip):
        if len(lista_ip) > 0:
            return lista_ip.pop(0)
        else: return None
    
    #function executed by the server whe it must choose an IP address for the client
    def choose_ip_for_client():
        return '123'

    server.add_function_choose( choose_ip_for_client)
    client.add_function_choose( choose_ip_server)

    def funct():
        yield env.timeout(1)
        client.send_DHCP_DISCOVERED()

    env.process( funct())

Add this three line of code for running the simulation at the end of the file.

e=spn.Environment()                 # create a new Environment
e.add_network(DHCP_network)         # add the network to the environment
e.run( 1, spn.__TRANSPORT_LOG_N__)  #run the simulation, and save the log information up to Transort level

• Open the terminal and run python prova.py
• Look in the same level wher the file prova.py is. There is a file named simpynet_log where the logging information of the simulation are stored.