Hidden vlan on the network

Unanswered Question
Apr 8th, 2008

dear sir,

We tried to delete off vlan 250 on the network by conf t --> no inter vlan 250 and no vlan 250 . However we did a show vlan counters as below, we still saw the vlan 250 is there. But with show vlan, we won't saw vlan 250 there. Vlan 250 is not needed in the network, some time it will automatically assigned vlan 250 to ap . The ap can't be work with vlan 250 . AP can work only with vlan 218 . Please advise how to trace this hidden vlan 250 and delete it off.

thanks.

Your effort shall be highly appreciated.

_________________________________________

sh vlan counters

Vlan Id : 218

--More-- L2 Unicast Packets : 293321393

L2 Unicast Octets : 200447765323

L3 Input Unicast Packets : 453252140

L3 Input Unicast Octets : 161798427123

L3 Output Unicast Packets : 263482746

L3 Output Unicast Octets : 190329187299

L3 Output Multicast Packets : 225474970

L3 Output Multicast Octets : 10825433065

L3 Input Multicast Packets : 0

L3 Input Multicast Octets : 0

L2 Multicast Packets : 115448864

L2 Multicast Octets : 8102981909

--More-- Vlan Id : 250

L2 Unicast Packets : 518

L2 Unicast Octets : 33228

L3 Input Unicast Packets : 0

L3 Input Unicast Octets : 0

L3 Output Unicast Packets : 0

L3 Output Unicast Octets : 0

L3 Output Multicast Packets : 0

L3 Output Multicast Octets : 0

L3 Input Multicast Packets : 0

L3 Input Multicast Octets : 0

L2 Multicast Packets : 34654672

I have this problem too.
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ciscograyaw Tue, 04/08/2008 - 13:31

If you did the no vlan 250 bit, you're probably just seeing residual counter data.

You can try 'clear vlan counters' and see if that clears them. If they still show up, you may want to do something like 'show run | i 250' to see if 250 is referenced anywhere else in your config.

chialun Wed, 04/09/2008 - 07:41

hi all,

The VLAN 250 still exists on the show vlan counters, only the counters has been cleared.Any idea how to complete delete remove the vlan 250 ? Any idea? Reload the distribution switch? Please advise and appreciation.

thanks.

vlan Id : 250

L2 Unicast Packets : 0

L2 Unicast Octets : 0

L3 Input Unicast Packets : 0

L3 Input Unicast Octets : 0

L3 Output Unicast Packets : 0

L3 Output Unicast Octets : 0

L3 Output Multicast Packets : 0

L3 Output Multicast Octets : 0

L3 Input Multicast Packets : 0

L3 Input Multicast Octets : 0

L2 Multicast Packets : 0

L2 Multicast Octets : 0

dbroder Wed, 04/09/2008 - 11:22

I'd do a reload on it before trying anything else.

HTH

Darren.

evsrajatgupta Wed, 04/09/2008 - 12:01

Hichialun,

(Please rate)

MAy be you are using c1900 switch. You can the delete the vlan in the fellowing manner.

Switch_A#vlan database

Switch_A(vlan)#no vlan 250

Switch_A(vlan)#Apply

Switch_A(vlan)#exit

You also use the below steps

Please note this requirs re-load and do not forget to take the configuration back.

1. Enter into the Privileged EXEC mode by typing enable.

If prompted for a password, enter class (if that does not work, ask the instructor).

Switch>enable

2. Remove the VLAN database information file.

Switch#delete flash:vlan.dat

Delete filename [vlan.dat]?[Enter]

Delete flash:vlan.dat? [confirm] [Enter]

If there was no VLAN file, this message is displayed.

%Error deleting flash:vlan.dat (No such file or directory)

3. Remove the switch startup configuration file from NVRAM.

Switch#erase startup-config

The responding line prompt will be:

Erasing the nvram filesystem will remove all files! Continue? [confirm]

Press Enter to confirm.

The response should be:

Erase of nvram: complete

4. Check that VLAN information was deleted.

Verify that the VLAN configuration was deleted in Step 2 using the show vlan command. If previous VLAN configuration information (other than the default management VLAN 1) is still present it will be necessary to power cycle the switch (hardware restart) instead of issuing the reload command. To power cycle the switch, remove the power cord from the back of the switch or unplug it. Then plug it back in.

If the VLAN information was successfully deleted in Step 2, go to Step 5 and restart the switch using the reload command.

5. Software restart (using the reload command)

chialun Wed, 04/09/2008 - 18:50

hi evsrajatgupta,

You seem to have a good advise and it's extremely helpful . :D However the switch model is Catalyst Switch 4506 with SUP V Module . So will the steps you propose work for this model ?

thanks.

rufus-mcmahon Wed, 04/16/2008 - 06:31

Check every switch on your network and verify the mode the switch is set to. (client, transparent or server) Before you delete vlan 250 from any switch, make sure you have only one switch configured as the server switch - then be sure to delete vlan 250 off of the server switch. Set the other switches to client mode and they will receive the updates as well. Remember, if the switch is set to transparent, it will not receive updates from the vtp server. The switches must also have the same vtp information configured on them in order for the updates between client and server to take place.

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