Cisco Support Community
Community Member

Drops errors in a vlan

Any of you can explane us the meaning of this error:

%CDP-4-NVLANMISMATCH:Native vlan mismatch detected on port 1/1

We have a problem. At the customer site,we saw that in a vlan 3 we have a lot of errors drops, we checked all the ports of the catalyst and anyone show us errors.

In this Vlan3 We have aprox. 1000 user (Hubs and Switches)

all PC and Server are on the same Vlan3 between switches and hubs.

Vlan3 is up, line protocol is up

Hardware is Cat6k RP Virtual Ethernet, address is 0005.01aa.b7fc (bia



Description: Desarrollo Tecnico

Internet address is

MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ARPA, loopback not set

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:00:00, output never, output hang never

Last clearing of "show interface" counters 00:02:03

Queueing strategy: fifo

Output queue 0/40, 0 drops; input queue 0/75, 15366 drops

5 minute input rate 18000 bits/sec, 24 packets/sec

5 minute output rate 32000 bits/sec, 70 packets/sec

3433 packets input, 293495 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

5116 packets output, 421467 bytes, 0 underruns

0 output errors, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

Any aidea ?

Community Member

Re: Drops errors in a vlan

First, make sure CEF, or IP ROUTE-CACHE is enabled. I'd also try changing the queueing strategy from FIFO to FAIR-QUEUE and see if that helps. I bet one of these will fix you up.

Community Member

Re: Drops errors in a vlan

The error message means there is a native vlan mismatch on port 1/1.

Native vlan is the vlan the port is in before trunk was configured.

For example, all ports are vlan 1 by default so if you configure trunk the native vlan is 1.

However, if you change it to vlan 10 and then apply trunk, the native vlan now is 10. So it seems that vlan the port 1/1 and it's neighbour before you configured trunk on them are different. so take the trunk off and change the vlan correctly and the re-apply trunk again.

If you are doing dot1q trunk on that port or regular access port, you are potentially briding vlans together.

Now, I understand this is on Catalyst 6000 MSFC. Don't if it is MSFC1 or MSFC2. MLS is automatically enabled on one and CEF is automatically enabled on the other. Now, you need to find out why there is so much traffic hitting the router. You should open a TAC case for effective troubleshooting.

Community Member

Re: Drops errors in a vlan

very good!

CreatePlease to create content