Cisco switches always have VLAN 1 as the default VLAN, which is needed for many protocol communication between switches like spanning-tree protocol for instance. Unfortunately you can’t change or even delete the default VLAN, it is mandatory.I am having two switches connected by access port but with two different vlan at both end. On both ends I got following Native VLAN mismatch discovered errors.
SW1# sh log
Aug 5 15:16:35.286: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/39 (14), with SW2 GigabitEthernet0/1/0 (2). Aug 5 15:17:33.992: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/39 (14), with SW2 GigabitEthernet0/1/0 (2). Aug 5 15:18:32.149: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/39 (14), with SW2 GigabitEthernet0/1/0 (2). Aug 5 15:19:28.217: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/39 (14), with SW2 GigabitEthernet0/1/0 (2). Aug 5 15:20:24.622: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/39 (14), with SW2 GigabitEthernet0/1/0 (2). Aug 5 15:21:17.736: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/39 (14), with SW2 GigabitEthernet0/1/0 (2). Aug 5 15:22:10.554: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/39 (14), with SW2 GigabitEthernet0/1/0 (2). Aug 5 15:23:01.778: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/39 (14), with SW2 GigabitEthernet0/1/0 (2). Aug 5 15:24:00.581: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/39 (14), with SW2 GigabitEthernet0/1/0 (2). SW1#
SW1#show cdp nei det | b SW2
Device ID: SW2
Entry address(es):
IP address: 172.18.14.11
Platform: cisco ISR4331/K9, Capabilities: Router Switch IGMP
Interface: GigabitEthernet1/39, Port ID (outgoing port): GigabitEthernet0/1/0
Holdtime : 151 sec
Version :
Cisco IOS Software, ISR Software (X86_64_LINUX_IOSD-UNIVERSALK9-M), Version 15.6(1)S1, RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2016 by Cisco Systems, Inc.
Compiled Wed 09-Mar-16 18:32 by mcpre
advertisement version: 2
VTP Management Domain: ''
Native VLAN: 2 (Mismatch)
Duplex: full
Power Available TLV:
Power request id: 0, Power management id: 1, Power available: 0, Power management level: -1
Management address(es):
IP address: 172.18.14.11
SW1#
The Configuration on the ports at both ends:
SW1(config-if)#do sh run int g1/39
Building configuration...
Current configuration : 133 bytes
!
interface GigabitEthernet1/39
description SW2 G0/1/0
switchport access vlan 14
switchport mode access
end
SW1#
SW2#sh run int g0/1/0
interface GigabitEthernet0/1/0
description MS-Network-MGMT
switchport access vlan 2
spanning-tree portfast
SW2#show cdp nei det
... Device ID: SW1 Entry address(es): IP address: 172.18.14.3 Platform: cisco WS-C4510R+E, Capabilities: Router Switch IGMP Interface: GigabitEthernet0/1/0, Port ID (outgoing port): GigabitEthernet1/39 Holdtime : 121 sec
SW2#
In circumstances like this, where you are sure the mismatch is not a real problem, you may consider to disable cdp for those interfaces to shut up those noise information.
SW2#show run int g1/39
Building configuration...
Current configuration : 148 bytes
!
interface GigabitEthernet1/39
description SW2 G0/1/0
switchport access vlan 14
switchport mode access
no cdp enable
end
SW2#
