[pox-dev] A flow removal question

[David Li]

Murphy,

I think I figured this out. This is what I used to display which flow
has been removed:

flow = event.ofp
log.info("flow: src %s dst %s",flow.match.nw_src, flow.match.nw_dst)

David


On Thu, May 28, 2015 at 10:21 AM, David Li <dlipubkey at gmail.com> wrote:
> Hi Murphy,
>
> Does this approach require my code keeps track of the flow table on
> the switch? I found sample code in topology.py:
>
> def _handle_FlowRemoved (self, event):
>     """
>     process a flow removed event -- remove the matching flow from the table.
>     """
>     flow_removed = event.ofp
>     for entry in self.flow_table.entries:
>       if (flow_removed.match == entry.match
>           and flow_removed.priority == entry.priority):
>         self.flow_table.remove_entry(entry)
>         self.raiseEvent(FlowTableModification(removed=[entry]))
>         return EventHalt
>     return EventContinue
>
>
> Is this what you are talking about?
>
> Thanks!
>
>
> On Tue, May 26, 2015 at 5:14 PM, Murphy McCauley
> <murphy.mccauley at gmail.com> wrote:
>> The information you want may not be available on the FlowRemoved event object itself, but as described in the "OpenFlow Events" section of the manual, the actual OpenFlow protocol message that caused the event is available on the event's .ofp attribute.  In this case, that means it's an ofp_flow_removed object.  If you look that up in the OpenFlow spec, you'll see there should be a .match attribute containing the match for the table entry as well as the .cookie (which, as I mention in my post on pox-dev a few minutes ago, is probably even more useful).
>>
>> -- Murphy
>>
>> On May 26, 2015, at 5:06 PM, David Li <dlipubkey at gmail.com> wrote:
>>
>>> Hi,
>>>
>>> I added a handler for flow removal. But I am wondering if it's
>>> possible to see from the event which flow has been removed. In the
>>> FlowRemoved class, I can't see how this info can be obtained easily.
>>> Maybe I am wrong.
>>