Hi all, I would like to know what's causing the native vlan mismatch to happen ? Also, what's the impact to the performance or connectivity of the problem? So far, my network still running without any problem. FYI, both Fa0/7 and Fa0/27 are set to access mode and both trunking between the switches are configured correctly. I can't figure out what has caused these error message as shown below. Sep 7 17:14:36: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/7 (4), with Cat3550_SW4 FastEthernet0/27 (6). Sep 7 17:15:08: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/7 (4), with Cat3550_SW2 FastEthernet0/30 (2). Appreciate your advice.