From: Paul Cosgrove (paul.cosgrove@heanet.ie)
Date: Sat May 31 2008 - 13:12:55 ART
The forwarding behaviour in VTP v1 & v2 has been discussed a few times
here. Apparently the behaviour changed at some point in the dim and
distant past, but the doc cd was not updated to reflect that.
Have a look at following post which includes a response from cisco on
the matter:-
http://www.groupstudy.com/archives/ccielab/200704/msg01533.html
It seems there is no difference in the forwarding behaviour between v1
and v2. If you define a VTP domain name on a switch set in transparent
mode, it will only forward VTP messages containing that domain name. So
having a different domain name on the transparent mode switch should be
enough.
If we were asked to block all VTP, regardless of domain name, we could
use transparent mode with an inbound mac acl matching type 0x2003.
mac access-list extended DENY-VTP
deny any host 0100.0ccc.cccc 0x2003 0x0
permit any any
interface FastEthernet0/13
mac access-group DENY-VTP in
Paul.
Thor Kopp wrote:
> With VTP V1 (the default) a switch in transparent mode will only forward vtp
> advertisments if the domain & version number match so if you use a random
> VTP domain for example you won't forward VTP messages learnt on trunk ports
> (because it's unlikely that the VTP domain will match).
>
> VTP V2 will forward VTP messages regardless of the VTP domain that is in the
> VTP message that it receives.
>
> - Thor
> On Sat, May 31, 2008 at 9:33 AM, Sadiq Yakasai <sadiqtanko@gmail.com> wrote:
>
>
>> Hmmm,
>>
>> I dont think setting the VTP mode to transparent will make the switch block
>> all VTP advertisements. The switches will only not originate VTP but will
>> still relay them from other switches.
>>
>> I agree with Paul, setting the switchport modes to access will do the
>> trick,
>> but not including the trunks that you have already set anyway, as doing so
>> will revert them back to access switchports and not satisfy the previous
>> ISL
>> encap requirement.
>>
>> HTH
>> Sadiq
>>
>>
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>
>
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