Hi,

I am working with OpenvSwitch 2.12.0 binaries install. I have configured an 
overlay VXLAN network as shown below and I used the tutorials to setup MAC 
learning.  The figure shows the IP address and the corresponding MAC address of 
the terminals connected to OVS. STP is enabled on all 4 OVS instances. Without 
configuring the link between OVS-1 and OVS-4, MAC learning works great. But 
once that link is connected to form a ring network, MAC learning on the 
switches seem to get confused and certain ports/ MAC address mapping is wrong. 
The table below shows the relevant information from the dump-flows from the MAC 
learning table. The notes column provides more details regarding the 
discrepancies.

Another observation is STP is blocked on port 6 of OVS-2 whereas from OVS-3, 
port 7 has it as STP-FORWARD. Shouldn't OVS-3 have port 7 blocked as well? Port 
6 on OVS-2 is the only blocked port on the entire network.

          [cid:image001.jpg@01D76BA1.EB164190]

OVS Instance

Correct Mapping of port to MAC address

Incorrect Mapping of port to MAC address

Notes

OVS-4

dl_dst=6a:6d:0c:f6:f5:83 actions=load:0x4->NXM_NX_REG0[0..15]
dl_dst=86:cf:71:7e:50:59 actions=load:0x5->NXM_NX_REG0[0..15]
dl_dst=32:09:e2:3d:6c:dc actions=load:0x5->NXM_NX_REG0[0..15]

dl_dst=6a:6d:0c:f6:f5:83 actions=load:0x5->NXM_NX_REG0[0..15]
dl_dst=86:cf:71:7e:50:59 actions=load:0x5->NXM_NX_REG0[0..15] 
dl_dst=32:09:e2:3d:6c:dc actions=load:0x5->NXM_NX_REG0[0..15]

Terminal 4 MAC is now on the wrong port. OVS-4 learns terminal 1's MAC on port 
5 even though OVS-2 and OVS-3 direct link is STP-blocked.

OVS-3

dl_dst=6a:6d:0c:f6:f5:83 actions=load:0x5->NXM_NX_REG0[0..15]
dl_dst=86:cf:71:7e:50:59 actions=load:0x7->NXM_NX_REG0[0..15]

dl_dst=6a:6d:0c:f6:f5:83 actions=load:0x7->NXM_NX_REG0[0..15]
dl_dst=86:cf:71:7e:50:59 actions=load:0x7->NXM_NX_REG0[0..15]

Terminal 4 MAC is now on the wrong port. OVS-3 doesn't realize port 6 on OVS-2 
is blocked.

OVS-2

dl_dst=6a:6d:0c:f6:f5:83 actions=load:0x6->NXM_NX_REG0[0..15]
dl_dst=32:09:e2:3d:6c:dc actions=load:0x6->NXM_NX_REG0[0..15]

dl_dst=6a:6d:0c:f6:f5:83 actions=load:0x5->NXM_NX_REG0[0..15]


Missing MAC learning for 32:09... for Terminal 3.

OVS-1

dl_dst=86:cf:71:7e:50:59 actions=load:0x5->NXM_NX_REG0[0..15]
dl_dst=32:09:e2:3d:6c:dc actions=load:0x6->NXM_NX_REG0[0..15]

dl_dst=86:cf:71:7e:50:59 actions=load:0x8->NXM_NX_REG0[0..15]
dl_dst=6a:6d:0c:f6:f5:83 actions=load:0x8->NXM_NX_REG0[0..15]

Terminal 1 MAC is now on the wrong port. Missing MAC learning for 32:09... for 
Terminal 3.


Is STP causing problems with MAC learning? I appreciate any feedback on this 
issue.

Thanks,
Usha


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