CDP-W-NATIVE_VLAN_MISMATCH

[jbpollard]

What exactly does CDP-W-NATIVE_VLAN_MISMATCH mean? Ports 49-50 are a portchannel to my dell 5448 switch.  Port gi1/1/24 is a connection to a voip poe switch I dont have access to because is managed by our phone provider.

03-May-2013 10:09:22 %CDP-W-NATIVE_VLAN_MISMATCH: Native VLAN mismatch detected on interface gi1/1/50.
03-May-2013 10:09:23 %COPY-N-TRAP: The copy operation was completed successfully
Copy succeeded
switch32f1d0#03-May-2013 10:09:54 % Native VLAN mismatch detected on interface gi1/1/24.

switch32f1d0#show int switchport gi1/1/50
Port : gi1/1/50
Port Mode: Trunk
Gvrp Status: disabled
Ingress Filtering: true
Acceptable Frame Type: admitAll
Ingress UnTagged VLAN ( NATIVE ): 100

Port is member in:

Vlan Name Egress rule Port Membership Type
---- -------------------------------- ----------- --------------------

Forbidden VLANS:
Vlan Name
---- --------------------------------

Classification rules:

Protocol based VLANs:
Group ID Vlan ID
------------ -------

Mac based VLANs:
Group ID Vlan ID
------------ -------

switch32f1d0# show interfaces port-channel

Load balancing: src-dst-mac.

Gathering information...
Channel Ports
------- -----
Po1 Active: gi1/1/49-50
Po2
Po3
Po4
Po5
Po6
Po7
Po8
Po9
Po10
Po11
Po12
Po13
Po14
Po15
Po16
Po17
Po18
Po19
Po20
Po21
Po22
Po23
Po24
Po25
Po26
Po27
Po28
Po29
Po30
Po31
Po32
switch32f1d0#show int switchport gi1/1/49
Port : gi1/1/49
Port Mode: Trunk
Gvrp Status: disabled
Ingress Filtering: true
Acceptable Frame Type: admitAll
Ingress UnTagged VLAN ( NATIVE ): 100

Port is member in:

Vlan Name Egress rule Port Membership Type
---- -------------------------------- ----------- --------------------

Forbidden VLANS:
Vlan Name
---- --------------------------------

Classification rules:

Protocol based VLANs:
Group ID Vlan ID
------------ -------

Mac based VLANs:
Group ID Vlan ID
------------ -------

[jbpollard]

Show run

http://pastebin.com/jKY4yivu

[Michal Bruncko]

> What exactly does CDP-W-NATIVE_VLAN_MISMATCH mean?

basically that means, that your switch observed native VLAN mismatch on reported switchports. This simply means, that both sides of that link has different native VLAN ID. This difference was spotted by switch with checking CDP packet from neighboring device on that affected port. CDP packet contains info about neighboring device (model, capability, remote port ID, and some other stuff including native VLAN).

Usually native VLAN (if you did not change it by yourself)  is default VLAN which is VLAN number 1. Possibly that's the case for neighboring devices that they use VLAN 1 as native VLAN. On the other side, SG300 uses VLAN 100 as native VLAN (which is automatically configured with smartport macros). You can change this behavior with following command: "macro auto built-in parameters switch $native_vlan 1", saving config and rebooting switch.

[jbpollard]

Ahh okay thanks,

Why is there one on my etherchannel port group? On the other side my dell switch is configured the same way with all the vlans and a native of 100.

03-May-2013 12:49:22 %CDP-W-NATIVE_VLAN_MISMATCH: Native VLAN mismatch detected on interface gi1/1/50., aggregated (1)

[Michal Bruncko]

probably native VLAN differ on port channel member ports on dell switch. you can check this with following command on SG unit:

switch32f1d0#show cdp neighbors GigabitEthernet 1/1/49 detail

switch32f1d0#show cdp neighbors GigabitEthernet 1/1/50 detail

there is a line named "Native VLAN"  - you can compare it from both commands.