[pox-dev] Flow rule installation using POX

[Sukheja, Himanshu]

Hello Murphy,

Thank you for you reply. I understand your concern that my POX controller may not be correctly connected to the switch. However, it is connected as whenever i put in "nodeS" command in my mininet CLI it shows me c0(i.e. pox).

As you recommended I read the links mentioned by you in your previous email. I am invoking pox with the openflow.of_1 --port=6653, So your last doubt is cleared.

The major problem I am facing is that I cannot even install any flow from my POX CLI. Although, I also parse these commands before trying to install a flow mod
POX>from pox.core import core
POX>import pox.openflow.libopenflow_01 as of
POX>from pox.lib.addresses import IPAddr


I would be really grateful if you could give me an example about how to install any flow on the switch from my POX controller CLI. As, I can successfully install flow from the switch side but not from controller side.


Thanks,

************************************************************************
Himanshu Sukheja

________________________________
From: Murphy McCauley <murphy.mccauley at gmail.com>
Sent: 14 March 2019 07:08
To: Sukheja, Himanshu
Cc: pox-dev at lists.noxrepo.org
Subject: Re: [pox-dev] Flow rule installation using POX

You are just creating a message, but that's not enough -- you have to send it to a switch.  This section of the POX manual may be of help:
https://noxrepo.github.io/pox-doc/html/#communicating-with-datapaths-switches<https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fnoxrepo.github.io%2Fpox-doc%2Fhtml%2F%23communicating-with-datapaths-switches&data=02%7C01%7Chxs376%40psu.edu%7Cf1db8043ac5d4b88564208d6a86d75b4%7C7cf48d453ddb4389a9c1c115526eb52e%7C0%7C0%7C636881585412243283&sdata=mBjaeQo7v2gOUFbhvMvIquCFEJwymwXylX8zCsOxFeU%3D&reserved=0>

You also might take a look at some of the sample POX components, particularly ones in the forwarding/ directory.

But I think you've got bigger problems.  By default, POX actually clears the tables on switches when they connect -- sending a command much like the one you've constructed.  So I think switches aren't connecting to POX.  Depending on what version of POX you're running, one possibility is that POX's OpenFlow component isn't running.  You might look at the documentation for the of_01 component in the manual:
https://noxrepo.github.io/pox-doc/html/#openflow-of-01<https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fnoxrepo.github.io%2Fpox-doc%2Fhtml%2F%23openflow-of-01&data=02%7C01%7Chxs376%40psu.edu%7Cf1db8043ac5d4b88564208d6a86d75b4%7C7cf48d453ddb4389a9c1c115526eb52e%7C0%7C0%7C636881585412253293&sdata=NlviWa9QM856%2F0RM0KyCozUB%2B1nIa8TI6QPLS%2FQq9xU%3D&reserved=0>

The manual mentions that POX will generally automatically load the of_01 (OpenFlow 1.0) component if another component that uses OpenFlow is loaded.  Since you're entering stuff in the CLI, maybe you aren't loading any OpenFlow-using component?  In that case, you'll need to launch of_01 manually.  If you're just running POX without any commandline arguments at all, you should probably read:
https://noxrepo.github.io/pox-doc/html/#invoking-pox<https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fnoxrepo.github.io%2Fpox-doc%2Fhtml%2F%23invoking-pox&data=02%7C01%7Chxs376%40psu.edu%7Cf1db8043ac5d4b88564208d6a86d75b4%7C7cf48d453ddb4389a9c1c115526eb52e%7C0%7C0%7C636881585412263297&sdata=lJ05u9k3QuCTYzgGnP3zDzqkbb1tM1lgAmKedQedxHE%3D&reserved=0>

Ultimately, you should see some log messages in POX about the switches connecting.  Are you?

Not really related to the above, but you mention how packets being dropped means the table entry is still there.  That's not true, generally speaking.  In general, an OpenFlow switch without any table entries doesn't forward any traffic (though it may encapsulate at least the headers and send it to the controller).

-- Murphy

On Wed, Mar 13, 2019 at 8:36 PM Sukheja, Himanshu <hxs376 at psu.edu<mailto:hxs376 at psu.edu>> wrote:
 have created a simple topology using Mininet in which I have created a single switch and connected it to a remote controller (POX). I installed a simple flow rule using Mininet CLI which commands the switch to drop all packets.

sh ovs-ofctl add-flow s1 priority=40000,hard_timeout=30,actions=drop

Now In POX CLI I run the following command

msg = of.ofp_flow_mod(command=of.OFPFC_DELETE)

Although now when I do a Dump-flow command on mininet terminal it still shows the flow is installed
Also, I tried to ping h1 and h2, and the packets are being dropped (which means that the flow is still there)


Could you please point out the error in my execution here.

Thanks
***********************************************
************************************************************************
Himanshu Sukheja
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