Mininet:
    1. miminet/mytopo.py:
        Take mininet/topo.json as input, build network topology.
    2. mininet/topo.json:
        *IMPORTANT*
        The file describe network topology based on following rule.
        i) Camera: c, Video sink: h, Switch: s
        ii) Camera and Sink are host, start from 1 ( c1, c2, h3, h4, h5 )
        iii) Switch start from 1 ( s1, s2, s3 )
        iv) Switch port start from 2

Ryu:
    1. ryu/topo.py:
        Provide API to operate network topology and link
        i) generate/read CPLEX input/result
        ii) update flow info
    2. ryu/flow.json:
        You can use the format to set current flow data,
        or feed CPLEX result instead.
    3. ryu/multicast.py:
        Ryu app.
        It uses ryu/topo.py to learn network topology and update flow info.
    4. ryu/test.py
        For ryu/topo.py testing.
        i) Shows how to use Topo to generate/read CPLEX input/result.
        ii) Shows how to update flow info with ryu/flow.json or CPLEX result.
    5. ryu/cplex.[in|out]
        Samples for CPLEX.