05-07-2007 05:11 AM - edited 03-05-2019 03:54 PM
Hi,
Can anyone provide any inputs regarding the below problem.
A 6509 with the CATos 8.2(1) is connected to 2950 with the IOS 12.1(22)EA4.
We are getting the below error in log in 6509
2007 Apr 26 02:42:52 GMT+8 +08:00 %CDP-4-NVLANMISMATCH:Native vlan mismatch detected on port 7/3
But not getting any native vlan mismatch in 2950. My question is why the log is not coming in 2950.
Note: both the switches are running the CDP v2. so there is no cdp version mismatch
The configurations are as follows.
6509
-------------
****************** show port ******************
* = Configured MAC Address
Port Name Status Vlan Duplex Speed Type
----- -------------------- ---------- ---------- ------ ----------- ------------
7/3 switch2 Fa0/9 connected 304 full 100 10/100BaseTX
****************** show vlan ******************
VLAN Name Status IfIndex Mod/Ports, Vlans
---- -------------------------------- --------- ------- ------------------------
304 Extension-VLAN active 382 7/3
****************** show cdp neighbors detail ******************
Port (Our Port): 7/3
Device-ID: switch2.<removed>
Device Addresses:
IP Address: <removed>
Holdtime: 128 sec
Capabilities: SWITCH IGMP
Version:
Cisco Internetwork Operating System Software
IOS (tm) C2950 Software (C2950-I6K2L2Q4-M), Version 12.1(22)EA4, RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2005 by cisco Systems, Inc.
Compiled Wed 23-Mar-05 17:25 by yenanh
Platform: cisco WS-C2950-24
Port-ID (Port on Neighbors's Device): FastEthernet0/9
VTP Management Domain: unknown
Native VLAN: 1 (Mismatch)
Duplex: full
System Name: unknown
System Object ID: unknown
Management Addresses:
IP Address: <removed>
Physical Location: unknown
2950
------------------------------
------------------ show run --------------------
interface FastEthernet0/9
speed 100
duplex full
!
------------------ show vlan ------------------
VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Fa0/1, Fa0/2, Fa0/3, Fa0/4
Fa0/5, Fa0/6, Fa0/7, Fa0/8
Fa0/9, Fa0/10, Fa0/11, Fa0/12
Fa0/13, Fa0/14, Fa0/15, Fa0/16
Fa0/17, Fa0/18, Fa0/19, Fa0/20
Fa0/21, Fa0/22, Fa0/23, Fa0/24
------------------ show cdp neighbors ------------------
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone
Device ID Local Intrfce Holdtme Capability Platform Port ID
switch1
Fas 0/9 133 T S I WS-C6509 7/3
05-07-2007 05:29 AM
Hi,
Port fa0/9 on your 2950 is not in trunk mode. :)
HTH
Regards,
Bjornarsb
05-07-2007 05:43 AM
Hi Friend,
Can you paste the port config information of 6509 switch? Only for the port which is connected o 2950 switch?
Also paste the output of "sh int fa0/9 switchport" from 2950 switch.
I believe 2950 interface is in dynamic desirable state which is trying to form a trunk which is not the case with 6509 switch port.
Regards,
Ankur
05-07-2007 04:27 PM
----------Port config in 6509 -----------------
set vlan 304 7/3
set trunk 7/3 off negotiate 1-1005,1025-4094
set spantree bpdu-guard 7/3,7/7 disable
set span 7/3 5/31 both inpkts disable learning enable multicast enable create
---------2950-------------------------
pofsw1102>sh int fa0/9 switchport
Name: Fa0/9
Switchport: Enabled
Administrative Mode: dynamic desirable
Operational Mode: static access
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: native
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Voice VLAN: none
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL
Protected: false
Appliance trust: none
05-07-2007 07:46 AM
The 6509 port is on VLAN 304
The 2950 port is on VLAN 1
Both sides must match VLAN's. So Change the 2950 to VLAN 304. Also, I would set VTP mode to transparent on the 2950.
I am assuming you are not trunking and all ports are access ports?
05-07-2007 06:35 PM
Yahh..you are correct but the CDP information message for native vlan mismatch should appear on both....right ? But its not appearing in 2950 at all...I am looking for the reason behind that.
05-07-2007 10:23 PM
Hi Sudipta,
Thanks for posting the information which I requested. Now what you see is an expected behavior and the reason behind is NATIVE VLAN is a concept only on trunk ports. Your Cat6k port is a normal access port as you have configured "set trunk
2950 interface is having default mode configuration on its interface and is working in "dynamic desirable mode" which means it will try to form a trunk with default native vlan as 1 which will be carried in CDP packets and will report Native Vlan mismatch on Cat6k only because the access vlan information on cat6k does not match Native Vlan which is coming in CDP packets from 2950.
HTH
Ankur
*Pls rate all helpfull post
05-08-2007 09:29 AM
Hi Ankur,
Thanks for ur response.
I have another similar question regarding this.
We have tested the similar scenario with other switches. Giving the details
--------------sw1(3550 48SMI Version 12.1(20)EA1a)------------------
interface FastEthernet0/4
switchport access vlan 3
switchport mode access
speed 100
duplex full
spanning-tree portfast
!
-------------- sh log -------------
*Mar 1 08:05:10.444 GMT+8: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/4 (3), with sw2 FastEthernet0/1 (1)
--------------sw2( 3548 XL Version 12.0(5)WC3b)------------------
interface FastEthernet0/1
spanning-tree portfast
!
-------------- sh log -------------
*Mar 1 08:12:23.358 PST: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/1 (1), with sw1 FastEthernet0/4 (3).
Here I am getting the message on both. Why ?
I dont have the output for sh int switchport command. Anyway in 3550 the port is in access mode. But not sure about the 3550XL. Can u pls. give any input regarding this ?
05-08-2007 09:41 AM
Ports on 3548XL are static access not dynamic desirable bydefault. Ports on 3550 are dynamic desirable by default.You have set the switchport mode to static access on both the switches.
Do the following on 3550 switch:
config t
default interface fa 0/4
on 3548Xl, assign the port on a different vlan other than the default vlan. Observe the error and let us know your finding.
-amit singh
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