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

[Weiyang Mo]

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.
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