native vlan mismatch on 2 2924 switches w/ only 1 vlan defined (same on both switches)

i'm getting the following message logged every minute:

Jul 1 14:56:30: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch
discovered on FastEthernet0/2 (0), with switchs1-cc-cab4.jct.ac.il
FastEthernet0/23 (1).

ok, there's lots in this group written about vlan mismatches.
i haven't seen anything with all ports on both switches in the same
vlan!

both switches are 2924-xl's w/ all 24 ports on each unit in vlan1.
the unit which logs the messages is running Version 11.2(8.2)SA6.
the other unit is running Version 12.0(5)WC5.

everythings seems to be working fine though.
each switch has several production servers on it, so we would have
noticed if there were connectivity or performance effects.

any additional insight would be appreciated.
tnx
ams

 

I'll assume that the trunk has been negotiated and that the original access
ports were at one point in different vlans. To set the native vlan on one
of the switches to match the other try this (works on 2950)

config t
int f0/2
switch trunk native vlan 1
end

You may be able to use the command "show interface f0/2 trunk" to view
trunking characteristics on the port in question.

Good luck,
-Jeff C

 

First, you should upgrade the IOS on both switches as they are both
subject to some semi-recently announced vulnerabilities. This may
also resolve some cdp version issues.

If you still have a problem, compare the configurations between the
switches to see what differences you have. Worst case, post the
configs (minus any passwords, encrypted or not).

 

Just enter
no cdp advertise-v2
in all boxes.
Or correct the native vlans .
It seems switchs1-cc-cab4.jct.ac.il uses some other native vlan than 1.
Regs
Hakan

 

tnx 4 the hint jeff, but
sho int fa0/2 swi (not trunk)
indicated that both switches had vlan 1 as the default native vlan.
i set it explicitly anyway, but the "vlan mismatch" messages still kept
coming.

the "no cdp advertise" as suggested by Håkan Månsson ()
stopped the mismatch messages.
it's still a mystery why they were coming altogether with both native vlans 1,
and negotiation disabled as seen below.

switchs1-cc-cab2>sho int fa0/2 swi
Name: Fa0/2
Switchport: Enabled
Administrative mode: static access
Operational Mode: static access
Administrative Trunking Encapsulation: isl
Operational Trunking Encapsulation: isl
Negotiation of Trunking: Disabled
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Trunking VLANs Enabled: NONE
Pruning VLANs Enabled: NONE

switchs1-cc-cab2>

switchs1-cc-cab4>sho int fa0/23 swi
Name: Fa0/23
Switchport: Enabled
Administrative mode: static access
Operational Mode: static access
Administrative Trunking Encapsulation: isl
Operational Trunking Encapsulation: isl
Negotiation of Trunking: Disabled
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Trunking VLANs Enabled: NONE
Pruning VLANs Enabled: NONE

Priority for untagged frames: 0
Override vlan tag priority: FALSE
Voice VLAN: none
Appliance trust: none
switchs1-cc-cab4>

tnx
ams