From: Mohammad Saeed (mzsaeed@gmail.com)
Date: Thu May 24 2007 - 14:45:01 ART
Yes, I agree, basically unless specifically required, VTP server and
client mode shall be used with VTP pruning enabled.
Regards,
Mohammad Zahed Saeed
On 5/24/07, Gustavo Novais <gustavo.novais@novabase.pt> wrote:
> I agree with you, the problem is that I cannot change or activate
> pruning, as it is not my network.
>
> My doubt is just that I cannot find any specific info confirming that
> behaviour, as it results of not-so-good design in my opinion, but that
> happens to work.
>
> Thanks
>
> Gustavo Novais
>
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Mohammad Saeed
> Sent: quinta-feira, 24 de Maio de 2007 18:16
> To: Cisco certification
> Subject: Re: Question about 802.1q trunking - Do not have any switch
> near to test...
>
> In my opinion, as no Pruning is in place, all VLANS will be allowed on
> trunk link and flooded traffic from all VLANS will pass through the
> trunk even if the respective VLAN does not exist on the other switch.
> So, if that VLAN does not exist on the other switch traffic will
> dropped. This is where Pruning comes, if you want to let the traffic
> pass on the trunk only for the VLANS that exist on the other end,
> enable VTP pruning on both switches.
>
> By default 802.1Q trunk tag all VLANS traffic except the Native VLAN,
> so as per this rule, if traffic is flooded in VLAN 10, suppose, when
> it will cross the Dot1Q trunk it shall be tagged with the respective
> VLAN ID, VLAN 10, so that receiving switch shall be able to contain
> the traffic in the VLAN 10.
>
> Hope this helps.
>
> Regards,
>
> Mohammad Zahed Saeed
>
> On 5/24/07, Gustavo Novais <gustavo.novais@novabase.pt> wrote:
> > Hello,
> >
> >
> >
> > Lately I faced a doubt while on a customer audit, that although does
> not
> > affect performance, has left me thinking...
> >
> >
> >
> > You have two switches (lets say 3550 and 2950) in VTP mode
> transparent,
> > interconnected through a dot1q trunk, without any vlan filtering on
> the
> > trunk ports, but both switches have different vlan databases. Some
> vlans
> > in common, some not.
> >
> >
> >
> > What will happen to the flooded traffic on those trunk ports on the
> > not-in-common (nic) vlans?
> >
> >
> >
> > Sh interface trunk tells me that not-in-common vlans are STP
> forwarding
> > and are obviously allowed on the trunk.
> >
> >
> >
> > Will the flooded traffic for one of those vlans cross the patch cable
> > (tagged), and be dropped by the other switch, who doesn't know that
> vlan
> > ID?
> >
> > Or will it simply not be forwarded over that particular link?
> >
> > Or will it be flooded through the trunks native vlan (on the receiving
> > switch)?
> >
> >
> >
> > Any ideas/comments/links pointing to info are helpful.
> >
> >
> >
> > Thanks
> >
> >
> >
> > Gustavo Novais
> >
> > #15622
> >
> >
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