[pox-dev] Controller to split traffic by subnet

[Murphy McCauley]

At least one of your problems is the same as was recently discussed in this post:
http://lists.noxrepo.org/pipermail/pox-dev-noxrepo.org/2013-May/000732.html

It also looks like your topology has a loop but that sufficient measures are not taken to prevent packets from looping.  If your subnet splitting was working, this wouldn't be a loop for IP, but still would but for non-IP.  This may be why you're getting a BUFFER_UNKNOWN area -- looped packets may be exhausting all the buffers.  You need to somehow modify your controller to prevent looping. One way might be to change the resend_packet to OFPP_ALL to use OFPP_FLOOD instead and then run the openflow.spanning_tree component.  You could also just modify it so that S7 and S8 use single-port output instead of flooding, never use one of the alternate paths, and don't do MAC learning.

As a sidenote, you might want to take a look at the log module -- there's no need to tee into a file; the log module can be configured to just write a file for you.

-- Murphy

On May 23, 2013, at 2:55 PM, Alison Chan wrote:

> Hello,
> 
> I'm having trouble designing my controller to split traffic by ip
> subnet. The relevant controller code, topology setup, and pox log file
> are in the linked gist:
> 
> https://gist.github.com/alis0nc/5639697
> 
> The topology and port assignnments look right as confirmed by 'net' in
> mininet. Here is what I'm doing:
> 
> * start mininet by sudo mn --custom ~/mininet/custom/topo-ac.py
> --topo=mytopo --controller=remote,ip=127.0.0.1,port=6633 --mac
> * set up IP addresses on the nodes as follows:
>    * h1: 10.0.0.1
>    * h2: 10.0.0.129
>    * h3: 10.0.0.2
>    * h4: 10.0.0.130
> * start PoX by pox/pox.py misc.my_controller 2>&1 | tee -i poxlog.txt
> * mininet> h1 ping -c1 h2
> * destination host unreachable
> * wait about 5 seconds
> * the errors start coming and don't stop
> 
> This is really my first OF controller past the tutorial so I apologise
> if I'm doing something really really stupid... But any assistance
> would be appreciated.
> 
> Cheers,
> --
> Alison Chan
> Kettering University (2015): BSCS (Security concentration), BSCE, Pre-Law minor
> Research Assistant, Department of Computer Science
> Secretary, Kettering University Allies, A-Section
> +1 909 278 7753
> chan7781 at kettering.edu
> 
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