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GreenMST floodlight module

Implementation of module for Floodligth which implements a MST over a network. The Floodlight controller implements the Openflow protocol, which specifications can be found here: Openflow spec

This project depends on Floodlight, which can be found here: Floodlight project on GitHub.

It has been tested with Mininet, which can be found here: Mininet project on GitHub.

License

This sofware is licensed under the Apache License, Version 2.0.

Information can be found here: Apache License 2.0.

Installation and configuration

This project has been developed and tested on Floodlight v0.90. After its installation the floodlight.jar must be copied within the root folder of this project.

At this point the project can be imported into Eclipse and run right away.

Block or turn-off ports

By deafult, ports are blocked to generate the minimum spanning tree of the network. At the beginning ports were turned off (to save energy in DC) but some difficulties occurred. Infact, turning off ports on the switches send to the controller a link removed message. The controller is unable to understand if a link goes down because of its decision or a manual setup. We suggest to leave the blocking decision on, anyway the following step can be performed to change to the previous behaviour:

  • Comment as follows line 179 in GreenMST.java file: // portMod.setMask(OFPortConfig.OFPPC_NO_FLOOD.getValue());
  • Then, uncomment as follows line 178 in GreenMST.java: portMod.setMask(OFPortConfig.OFPPC_PORT_DOWN.getValue());

Create a runnable file

It is possible to create a greenmst.jar with the compiled files from this project. According to Floodlight command sintax, you can integrate the jar file to your Floodlight installation running the command:

java -cp floodlight.jar:greenmst.jar -Dlogback.configurationFile=logback.xml net.floodlightcontroller.core.Main -cf floodlight.properties

The parameters specified have the following meaning:

  • logback.xml is the XML file which permits to configure the log facility for the running instance of Floodlight
  • floodlight.properties is the file specifying the properties for the running instance of Floodlight, it is configred to start the GreenMST module provided with this project.

Utilities

In the scripts folder this projects provides some utility file that could be helpful to perform typical operations:

  • four-switch.py is a mininet custom topology file which permits to create a four switches full meshed topology;
  • startTopo.sh is a bash script which permits to start mininet with the four-switch topology (it assumes mininet is installed in the home for the user, and that the four-switch.py file is copied in the custom folder inside mininet);
  • viewGreenMSTapis.sh is a bash script that permits to query and show the results for the REST APIs;
  • setTopoCosts.sh is a bash script that permits to upload new topology costs via the REST APIs.

REST APIs

This project offers the following REST APIs:

  • http://controller-ip:8080/wm/greenmst/topoedges/json: only supports GET and shows all edges in the topology
  • http://controller-ip:8080/wm/greenmst/mstedges/json: only supports GET and shows all edges in the MST computed from the topology
  • http://controller-ip:8080/wm/greenmst/redundantedges/json: only supports GET and shows all redundant edges (edges in the topoloty but not in the computed MST)
  • http://controller-ip:8080/wm/greenmst/topocotsts/json: supports GET and POST and permits to view/modify the costs for all edges in the topology

Tests

In this section a typical use case will be presented to show how this project could be used to achieve important results in network optimization and configuration.

Use case

The following use case has been implemented:

  • realization of a four switches full mashed topology with mininet;
  • GreenMST needs to compute a minimum spanning tree and send commands to close un-necessary ports to switches so that loops are avoided;
  • visualization of the MST deployed on the network via the REST APIs developed by GreenMST;
  • modification of the costs for all links to prove that GreenMST is able to compute a new minimum spanning tree on the provided costs and so adapt the network to the updated situation.

With this use case it is possible to prove that the GreenMST is working by identifying the correct spanning tree which optimizes all switch-to-switch connections. It is also possible to prove that by creating an agent which senses the network conditions and triggers an update of link costs, GreenMST could be able to real-time adapt the network to changing configurations.

Step by step tutorial

To test this software a implementation the following steps have been executed:

  • We have defined a four switches fully mashed topology in mininet. The costs for all edges of the topology are as shown by command:

    $ ./viewGreenMSTapis.sh -a topocosts
[
   {
     "1,2": 1, 
     "1,3": 4, 
     "1,4": 2, 
     "2,3": 3, 
     "2,4": 4, 
     "3,4": 1
   }
]

  • At this point the topology can be shown with the following command:

    $ ./viewGreenMSTapis.sh -a topoedges
[
   {
     "cost": 1, 
     "destinationPort": 3, 
     "destinationSwitch": "00:00:00:00:00:00:00:03", 
     "sourcePort": 3, 
     "sourceSwitch": "00:00:00:00:00:00:00:04"
   }, 
   {
     "cost": 2, 
     "destinationPort": 3, 
     "destinationSwitch": "00:00:00:00:00:00:00:01", 
     "sourcePort": 1, 
     "sourceSwitch": "00:00:00:00:00:00:00:04"
   }, 
   {
     "cost": 1, 
     "destinationPort": 1, 
     "destinationSwitch": "00:00:00:00:00:00:00:02", 
     "sourcePort": 1, 
     "sourceSwitch": "00:00:00:00:00:00:00:01"
   }, 
   {
     "cost": 4, 
     "destinationPort": 3, 
     "destinationSwitch": "00:00:00:00:00:00:00:02", 
     "sourcePort": 2, 
     "sourceSwitch": "00:00:00:00:00:00:00:04"
   }, 
   {
     "cost": 3, 
     "destinationPort": 2, 
     "destinationSwitch": "00:00:00:00:00:00:00:02", 
     "sourcePort": 2, 
     "sourceSwitch": "00:00:00:00:00:00:00:03"
   }, 
   {
     "cost": 4, 
     "destinationPort": 2, 
     "destinationSwitch": "00:00:00:00:00:00:00:01", 
     "sourcePort": 1, 
     "sourceSwitch": "00:00:00:00:00:00:00:03"
   }
]

  • Running the GreenMST the MST computed is as follows:

    $ ./viewGreenMSTapis.sh -a mstedges
[
   {
     "cost": 1, 
     "destinationPort": 3, 
     "destinationSwitch": "00:00:00:00:00:00:00:03", 
     "sourcePort": 3, 
     "sourceSwitch": "00:00:00:00:00:00:00:04"
   }, 
   {
     "cost": 2, 
     "destinationPort": 3, 
     "destinationSwitch": "00:00:00:00:00:00:00:01", 
     "sourcePort": 1, 
     "sourceSwitch": "00:00:00:00:00:00:00:04"
   }, 
   {
     "cost": 1, 
     "destinationPort": 1, 
     "destinationSwitch": "00:00:00:00:00:00:00:02", 
     "sourcePort": 1, 
     "sourceSwitch": "00:00:00:00:00:00:00:01"
   }
]

    Which represent the minimum spaning tree computed on the topology (it is possible to verify that only edges with low costs have been kept open).

  • This MST has also been deployed on the switches by closing the ports for the unused links. For example with mininet it is possible to verify that the port on switch 4 has been closed with the command:

    mininet> s4 dpctl show tcp:127.0.0.1:6637
features_reply (xid=0x4a7cacc5): ver:0x1, dpid:4
n_tables:255, n_buffers:256
features: capabilities:0xc7, actions:0xfff
 1(s4-eth1): addr:a2:8f:c2:a8:6d:57, config: 0, state:0
     current:    10GB-FD COPPER 
 2(s4-eth2): addr:ba:d8:da:a1:26:5b, config: 0x1, state:0x1
     current:    10GB-FD COPPER 
 3(s4-eth3): addr:0e:1d:34:0a:18:b2, config: 0, state:0
     current:    10GB-FD COPPER 
 LOCAL(s4): addr:82:45:0b:bc:e8:44, config: 0x1, state:0x1
get_config_reply (xid=0xe67cf3b9): miss_send_len=0

    It is possible to see that port 2, for instance, has a state of 1 which means the port is down.

  • Now it is possible to submit new costs for the links, for example with the followin commands:

    $ ./setTopoCosts.sh 
{
   "status": "new topology costs set"
}

$ ./viewGreenMSTapis.sh -a topocosts
[
   {
     "1,2": 10, 
     "1,3": 40, 
     "1,4": 20, 
     "2,3": 30, 
     "2,4": 10, 
     "3,4": 40
   }
]

  • GreenMST module has recomputed a new MST, it is possible to check this with the command:

    $ ./viewGreenMSTapis.sh -a mstedges
[
   {
     "cost": 10, 
     "destinationPort": 1, 
     "destinationSwitch": "00:00:00:00:00:00:00:02", 
     "sourcePort": 1, 
     "sourceSwitch": "00:00:00:00:00:00:00:01"
   }, 
   {
     "cost": 10, 
     "destinationPort": 3, 
     "destinationSwitch": "00:00:00:00:00:00:00:02", 
     "sourcePort": 2, 
     "sourceSwitch": "00:00:00:00:00:00:00:04"
   }, 
   {
     "cost": 30, 
     "destinationPort": 2, 
     "destinationSwitch": "00:00:00:00:00:00:00:03", 
     "sourcePort": 2, 
     "sourceSwitch": "00:00:00:00:00:00:00:02"
   }
]

    This command shows a different MST than the previous one due to fact the all costs have changed.

  • The new MST has been deployed also on the switches, as show by mininet command:

    mininet> s4 dpctl show tcp:127.0.0.1:6637
features_reply (xid=0x461fa8c): ver:0x1, dpid:4
n_tables:255, n_buffers:256
features: capabilities:0xc7, actions:0xfff
 1(s4-eth1): addr:a2:8f:c2:a8:6d:57, config: 0x1, state:0x1
     current:    10GB-FD COPPER 
 2(s4-eth2): addr:ba:d8:da:a1:26:5b, config: 0, state:0
     current:    10GB-FD COPPER 
 3(s4-eth3): addr:0e:1d:34:0a:18:b2, config: 0x1, state:0x1
     current:    10GB-FD COPPER 
 LOCAL(s4): addr:82:45:0b:bc:e8:44, config: 0x1, state:0x1
get_config_reply (xid=0x59b0cd47): miss_send_len=0

    The port 2 is now active while port 1 and 3 are down.