Same MAC address in multiple VLANs

Hello Team,
Can you please help me out with this:

interface Ethernet46
   description CUST-COPROSYS-DIRECT
   load-interval 5
   switchport trunk native vlan 50
   switchport trunk allowed vlan 50,705,1373
   switchport mode trunk
   ip access-group acl_l3_peering_vlan_in in
   ipv6 access-group acl_v6_l3_peering_vlan_in in
   no lldp transmit
   no lldp receive
   switchport port-security maximum 3
   switchport port-security violation protect
   spanning-tree bpduguard enable
!
show mac address-table int et46
Vlan     Mac Address      Type       
---- ----------- ---- ----- ----- ---------
50        0018.194a.afd0  DYNAMIC 
50        001b.0de6.ab80 DYNAMIC 
705      001b.0de6.ab80 DYNAMIC 
1373    001b.0de6.ab80 DYNAMIC 

Here we can see that the address 001b.0de6.ab80 was learnt over multiple VLANs. Does that indicate the presence of duplicate NICs or something else?
Warm regards.

In switch supports independent vlan learning, same mac-address can be learnt on different vlans. while mac lookup is based on vlan-id + dst-mac. In case of shared vlan learning this is not supported. Normally most asics today support IVL tables

1 Like

Hello Rushabh

This is normal behaviour. Notice that the Ethernet46 interface is a TRUNK interface configured with three VLANs. That means that this trunk connects to THREE separate VLANs. This port however has only one MAC address. So it is expected that this one interface MAC address will be assocated with all of the VLANs included in the trunk.

I hope this has been helpful!

Laz