From: James Ventre (messageboard@ventrefamily.com)
Date: Wed Mar 15 2006 - 14:52:10 GMT-3
> "The client needs to have the configuration number changed to 0, >owever
> there is no IOS command (to my knowledge) to do this."
Change the domain name ... then change it back. That will reset it to 0.
James
Jason Couch wrote:
> In regards to:
>
> "The client needs to have the configuration number changed to 0, however
> there is no IOS command (to my knowledge) to do this."
>
> I believe changing the vtp mode to transparent and then back to client
> or server will reset the configuration revision.
>
> Test it out, but from what I remember, this worked for me...
>
> Jason
>
>
> ----- Original Message ----- From: "Martin Dean" <mdean@diatac.co.uk>
> To: <ccielab@groupstudy.com>
> Sent: Wednesday, March 15, 2006 11:47 AM
> Subject: Re: VTP client overwriting server ?
>
>
>> Hi
>>
>> This 'feature' has always been the case with IOS switches, no matter what
>> model. This does not happen in the CatOS switches, as the VLAN info gets
>> detected when rebooted and needs to receive a VTP message from a
>> server or
>> client on the network to re-learn VLAN data.
>> An IOS client when it sees a VTP packet with the correct domain name and
>> password checks the configuration number, if it is the same it is
>> ignored,
>> if it is higher the client will update its VLAN database, HOWEVER if the
>> revision number is lower, the client will send a VTP update message
>> containing information of the clients VLANs. If the VLAN data is
>> different
>> than the servers VLANs or any other switch in the network, the VLANs in
>> those switches will be deleted/changed to the clients VLAN info.
>> This has occurred many times in production networks, a well known
>> American
>> banks trading floor in the UK went down for a time - some say for an
>> hour,
>> some say longer.
>> This problem usually occurs when the domain name is used on multiple
>> sites
>> or in a test lab environment and multiple changes to VLAN info is
>> generated
>> causing the client switch to have a high configuration number.
>> The only way to stop this from happening is to use different domain
>> names OR
>> password in different locations, buildings, departments.
>> The client needs to have the configuration number changed to 0, however
>> there is no IOS command (to my knowledge) to do this.
>> To accomplish this, the domain name needs to be changed. My advice
>> which I
>> give to students attending Cisco courses is to always have the domain
>> name
>> at some nonsensical name, which will require changing in a production
>> environment.
>> Alternately, delete the vlan.dat file, when the switch is NOT
>> connected to
>> the network and reboot. If it is connected to the network, the file
>> will be
>> regenerated when a VTP message arrives, as the VTP / VLAN info is still
>> current in the RAM
>> There are many financial institutions that do not use VTP - set mode to
>> Transparent, because of this largely un-documented feature.
>> I personally got this changed on the CWENT 2.5 course and I have
>> checked it
>> has also been changed in the latest BCMSN 2.2 course. Course writers are
>> finally waking up to this 'feature' and the knowledge will slowly
>> disseminate its way to the general populace. As the courses get changed
>> hopefully so will the written material out of CiscoPress and other
>> publishers - but in the meantime BEWARE.
>>
>> Cheers
>> Martin
>>
>> ----- Original Message -----
>> From: "Carlos Mendioroz" <tron@huapi.ba.ar>
>> To: <ccielab@groupstudy.com>
>> Sent: Monday, March 13, 2006 8:49 PM
>> Subject: VTP client overwriting server ?
>>
>>
>>> Hi,
>>> I've just received 2 conflicting pieces of information.
>>> Well, both conflicted with what I supposed I knew...
>>>
>>> 1- IOS VTP clients do keep VLAN information in nvram
>>> 2- IOS VTP clients may overwrite a VTP server
>>> (so the message was, beware even more than what you used to
>>> from vlan info from a shelf switch).
>>>
>>> #1 I have confirmed. You pass some VLANs to a client, you isolate the
>>> client, you reload the client... and you have your VLANs.
>>> Cisco says you would not... well, at least says so in many places.
>>>
>>> #2 I have been unable to reproduce... even having a client with higher
>>> revision number talk to a server does not do the trick.
>>> The client will keep its higher version though...
>>>
>>> So here: Does anybody have conclusive info of #2 being true or false ?
>>> In case it is true, would you mind sharing a list of steps to make it ?
>>>
>>> Yours truly (confused :)
>>> -Carlos
>>>
>>> _______________________________________________________________________
>>> Subscription information may be found at:
>>> http://www.groupstudy.com/list/CCIELab.html
>>>
>>>
>>> --
>>> No virus found in this incoming message.
>>> Checked by AVG Free Edition.
>>> Version: 7.1.375 / Virus Database: 268.2.1/279 - Release Date:
>>> 10/03/2006
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Sat Apr 01 2006 - 10:07:38 GMT-3