[pox-dev] l2_learning_tutorial flow rules (strange behavior?)

[Murphy McCauley]

Yeah, that sounds about right. The new resend stuff just lets you ignore
whether the packet was actually buffered at the switch or not.

-- Murphy
On Oct 2, 2012 1:14 PM, "Tmusic" <Tmusic987 at gmail.com> wrote:

> Thanks for the quick response!
> l2_pairs is indeed a great example!
> I had to change the code for flooding the packet in order to get it
> working in the stable branch (with buffers as in l2_learning_tutorial). Is
> this the right way to do it?
>
>
> 2012/10/1 Murphy McCauley <murphy.mccauley at gmail.com>
>
>> Yes, that's always going to happen with l2_learning_tutorial.  This is,
>> in fact, an example of how NOT to try to write a learning switch, but
>> without proper context.  I deleted it in development fork/branch a while
>> back, but looks like I never did on the master branch.  I have done so now.
>>
>> The problem you're seeing here was actually just discussed on this list a
>> few days ago.  The issue is that the "learned" rules result in hiding other
>> packets from the controller, so it never learns all the destinations.
>>
>> If you want a good example of a switch for a tutorial, look at
>> forwarding.l2_pairs or samples.of_tutorial.  l2_pairs gets around the issue
>> of hiding other sources by only installing rules for each PAIR of learned
>> addresses.  These may only be available in the betta (development) branch.
>>
>> -- Murphy
>>
>> On Oct 1, 2012, at 11:38 AM, Tmusic wrote:
>>
>> > Hi,
>> >
>> > I'm trying to learn how to establish flow rules by studying
>> l2_learning_tutorial, but I'm experiencing rather strange behavior.
>> >
>> > On a VM with mininet (one switch, three hosts) and POX installed I
>> first start up mininet and then the l2_learning_tutorial (the behavior is
>> easier to see this way).
>> > I added one line after the flow installing to see what happens:
>> print 'added route to', packet.src,'(packet destined to',packet.dst,')'
>> >
>> > When I perform pingall in mininet (one or more), the same routes are
>> added over and over again (see print statement above).
>> > Dpctl shows that only two entries are being added (I expected three):
>> >
>> >   cookie=0, duration_sec=268s, duration_nsec=529000000s, table_id=0,
>> priority=32768, n_packets=16, n_bytes=1344, idle_timeout=0,hard_timeout=0,
>> > dl_dst=00:00:00:00:00:02,actions=output:1
>> >   cookie=0, duration_sec=268s, duration_nsec=463000000s, table_id=0,
>> priority=32768, n_packets=11, n_bytes=910,
>> idle_timeout=0,hard_timeout=0,dl_dst=00:00:00:00:00:03,actions=output:2
>> >
>> > The packets seem to keep going to the controller.
>> >
>> > Any ideas?
>> >
>> > Thank you in advance!
>> >
>> > Tim
>> >
>> >
>> >
>> >
>> >
>> >
>>
>>
>
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