04-25-2024 01:14 PM
Switch A, Cisco 9300, VTP mode transparent
interface GigabitEthernet1/0/5
switchport access vlan 3
switchport mode access
Switch B, Cisco 3560, VTP mode transparent
interface GigabitEthernet1/0/1
switchport access vlan 3
switchport mode access
Vlan 3 (L2) vlan created on both switches
CDP is running on both switches
When I bring the ports up, I get these messages on the 9300:
Apr 25 14:33:17.240 CDT: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/0/5 (3), with Switch GigabitEthernet1/0/1 (1).
Apr 25 14:33:18.240 CDT: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/0/5 (3), with Switch GigabitEthernet1/0/1 (1).
Apr 25 14:33:19.239 CDT: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/0/5 (3), with Switch GigabitEthernet1/0/1 (1).
Apr 25 14:33:20.241 CDT: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/0/5 (3), with Switch GigabitEthernet1/0/1 (1).
Apr 25 14:33:21.241 CDT: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/0/5 (3), with Switch GigabitEthernet1/0/1 (1).
Apr 25 14:33:22.244 CDT: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/0/5 (3), with Switch GigabitEthernet1/0/1 (1).
Apr 25 14:33:23.247 CDT: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/0/5 (3), with Switch GigabitEthernet1/0/1 (1).
Apr 25 14:34:00.561 CDT: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/0/5 (3), with Switch GigabitEthernet1/0/1 (1).
I do not know why. How do you have any protocol reporting a native vlan mismatch when there is not VTP communication and neither port is configured as a trunk?
04-25-2024 01:57 PM
CDP itself sends its port's native VLAN as a TLV with type 0x000a.
https://learningnetwork.cisco.com/s/article/cisco-discovery-protocol-cdp-x
https://wiki.wireshark.org/CDP
You can verify which native VLAN each port is advertising with a packet capture and decode.
04-25-2024 02:13 PM
Hi,
Can you post the output of "sh cdp nei deti" so we can see what Native vlan is configured on the switches?
HTH
04-25-2024 06:12 PM
Hello,
VTP doesn't send "Native VLAN" information, so regardless if you have it configured or not you will see those messages from CDP which is running between the switches.
Secondly you don't need a "trunk" link to have a native VLAN. By definition a Native VLAN is just an untagged VLAN on that interface. As a result any port in access mode with a vlan associated to it is running a "Native VLAN". For obvious reasons its not called a Native VLAN on an access port but just an access VLAN.
You could try configuring both interfaces as a trunk link to see if the error resolves. Any particular reason you're using access ports to connect network switches?
-David
04-25-2024 07:33 PM
David makes a very good point that VTP does not have anything to do with native vlan mismatch. In addition to the show cdp neighbor detail requested by Reza it might be helpful to see the output of show interface status from both switches.
04-25-2024 09:25 PM - edited 04-25-2024 11:48 PM
the CDP send native VLAN in port which is trunk I check in Lab this point, and it dont send it if the port is access
MHM
04-25-2024 11:46 PM
show switchport interface 1/0/5 and 1/0/1
share this in from both SW
MHM
04-26-2024 07:19 AM
As the others, and you, have already noted, this should not be happening between two access port configured with same VLAN number. VTP mode should be irrelevant and VTP doesn't run on access ports.
So, either you've encountered some bug or the limited interface config information you've posted is incorrect. Posting the information requested within the other replies would be very helpful.
BTW, two possibly errors that immediately jump to my mind are, first the config information you've posted is from a current show running-config? Second, it's g1/0/5<>g1/0/1 not g1/0/1<>g1/0/5? (I.e., you're sure you've identified the correct port per switch, as I suspect both switches have both those ports.)
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