[ovs-discuss] possible bug when falling back to the normal switch

[Tim Huang]

Hi there,

I am doing some test for my controller to handle the situation when some of the switches in the topology lose the connection to the controller.  The part of the topology will be something like this:

S1(DPID:11,port4)——(DPID:23,port3)S13(DPID:23,port2)—— (DPID:22,port3)S12

At first, all the switches are connected to the controller. All the switches controlled by controller send LLDP and special broadcast to all their ports.Then, I set the S13 to be standalone mode, using command to delete the controller for S13. S1, S12 will still send LLDP and  special broadcast for all their ports from controller’s packet_out . After falling back, I found the S13 can receive the special broadcast for both sides, but will only forward one side broadcast to the other. For example, S13 can receive S12’s broadcast and forward it to the S1, and it also can receive the broadcast from S1 but won’t forward it to S12. I used the wireshark to monitor the interfaces to get the conclusion. It doesn’t happen every time.  But the frequency is very high. 

What’s more interesting is if I fall back the switch and delete the controller before I start the controller,  it will not happen at all.

Is there any idea about this?

BTW: I used 1.9.3 and also tried with 2.3.1, the situation is the same.