Pinging the group again with this issue. Has anyone been able to get MAC
learning to work in a ring topology? I tried enabling secure mode as well as
STP in a standalone mode, but haven't been able to get it to work. Thanks in
advance for your response.
Thanks,
Usha
From: Seshadri, Usha (US)
Sent: Sunday, June 27, 2021 10:15 PM
To: ovs-discuss@openvswitch.org
Subject: MAC Learning not working correctly in a ring network with STP enabled
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:image002.jpg@01D76E81.5CD24680]
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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