topologydb.rst

Dumping the network state

You might need to access the state of the network (e.g., the nodes, the links or the assigned ip addresses) from a program outside of the python script launching the network. IPMininet allows you to dump the state of network to a JSON file through the ~ipmininet.topologydb.TopologyDB class.

The following code stores the network state to "/tmp/topologydb.json" and load it again afterwards. Note that you can read this file from any other program that can parse JSON files.

topologydb

from ipmininet.iptopo import IPTopo from ipmininet.ipnet import IPNet from ipmininet.topologydb import TopologyDB

class MyTopology(IPTopo):

pass # Any topology

net = IPNet(topo=MyTopology()) try: # This saves the state of the network to "/tmp/topologydb.json" db = TopologyDB(net=net) db_path = "/tmp/topologydb.json" db.save(db_path)

# This can be recovered from a new TopologyDB object or by loading # the json file in any other program TopologyDB(db=db_path)

# The backup of the network can be done before or after the start of # the daemons. Here it is done before. net.start()

except:

net.stop()

The produced JSON file has the following format:

{
    "<node-name>": {
        "type": "<node-type>",
        "interfaces": ["<itf1-name>"],
        "<itf1-name>": {
            "ip": "<itf1-ip1-with-prefix-len>",
            "ips": ["<itf1-ip1-with-prefix-len>",
                    "<itf1-ip2-with-prefix-len>"],
            "bw": 10
        },
        "<neighbor1-name>": {
            "name": "<itf1-name>",
            "ip": "<itf1-ip1-with-prefix-len>",
            "ips": ["<itf1-ip1-with-prefix-len>",
                    "<itf1-ip2-with-prefix-len>"],
            "bw": 10
        }
    }
}

Note that the <node-type> can be any of switch, router or host.

from ipmininet.clean import cleanup cleanup(level='warning')

try:

MyTopology

except NameError:

MyTopology = None

if MyTopology is not None:

from ipmininet.ipnet import IPNet net = IPNet(topo=MyTopology()) net.start()

try:

net

except NameError:

net = None

if net is not None:

net.stop()