[pox-dev] What does "Not flooding , holddown active " refer to ?

[Sam Russell]

The l2_learning module is designed to only flood some packets so as
not to overload itself.

If you're expecting a lot of broadcast traffic, you could modify it to
add a flow that floods broadcast packets on the switch while sending a
copy to the controller, and making the controller learn MAC addresses
from these packets while not trying to forward them once it's finished
with them

Sent from my iPhone

On Oct 10, 2012, at 7:38 AM, Weiyang Mo <moweiyang1988 at gmail.com> wrote:

> Hi,
>
> I saw some strange behaviors when I play with a few OpenFlow switches and IXIA traffic generator.
>
> The traffic generator server/host don't act as normal PCs thus learning switch will not work. That means that even the packets from source are flooded to the destination, the destination will not reply.
>
> I try to solve this issue by also sending some packets from destination to let controller know where is the destination, then the source packets will be forwarded to destination according to my OSPF algorithm.
>
> However I found something really strange that the packets are not flooded to all ports although using OFPP.ALL.  the topology is as follows:
>
>                    PC1   ----- SW1 --------SW2--------PC2
>                                        |                  |
>                                     IXIA1             IXIA2
> I send traffic from IXIA1 to IXIA2. Since IXIA2 never replys as I mention above, the controller should flood packets out of all ports. However I find that not all ports are flooded such as PC2 and IXIA2 which connects to SW2.  From the controller side, I see some information "Not flooding, holding down active"
>
> I'm not sure whether the "hold down" stops packets flooding all ports. And what does hold_down mean?
>
> BTW, another strange behavior is that this "not all flooded" issue not always happen.  If I run the controller a few times, sometimes flooding all ports, sometimes not... And when it's not, it seems packets are dropped on some switches?
>
> Thanks very much.