Friends,
Good day. I strongly believe I have a bug to report to Cisco but I don't have any account to do so ;(
In short.
Two vlans on a N9K-C9396PX.
Vlan A is bridged to a VNI and then goes as native to a trunk switchport (A).
Vlan B is NOT bridged to a VNI. Switched to the same switchport as VLAN A and also switched to some other port with other vlans /not necessarily together with VLAN A.
MAC address aaaa.bbbb.cccc /example, it can be any/ is seen over BOTH vlans on ingress from the switchport (A). It's just due to multiple subinterfaces on one and same NIC on the server behind the trunk switchport (A).
End result: the mac address is blackholed. No communication between it and any other mac address in the table can ever take place. show mac address-table dynamic vlan B displays that the mac address which is common to both vlans is not learned.
Otherwise explained, the issue is seen when one and same mac is learned on the native vlan of a trunk port plus any other trunk vlan on the same trunk port, and then only one of the vlans has to go to the NVE while the other vlan remains switched.
Workarounds:
1. remove any native vlans and rework all switchport as tagged without any access or native stuff, OR
2. change all mac addresses on each NIC in order to make sure every subinterface is operating an unique mac address.
No physical loops or anything alike. No logs about that either. Just traffic blackholing.
Known impacted version: NX-OS 9.3.8 /no capability to check on newer yet, working on that/
Anybody seen this?
